September 1987 

Mean and Peak 

Wind Load Reduction on 

Heliostats 

Colorado State University 

Fort Collins, Colorado 

Prepared under Subcontract No. XK-646034-1 
SERVSTR-253-3212 

UC Category: 62a 

DE87012281 

Mean and Peak 

Wind Load Reduction on 

Heliostats 

Colorado State University 

Fort Collins, Colorado 

Prepared under Subcontract No. XK-6-06034-1 

SERl Technical Monitor: Al Lewandowski 

Solar Energy Research institute 

A Division of Midwest Research Institute 

1617 Cole Boulevard 

Golden, Colorado 804011 -3393 

Prepared for the 

U.S. Department of Energy 

Contract No. DE-AC029-83CH 1 0093 
NOTICE 

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FOREWORD 

The research and development described in this document was conducted within 

the U.S. Department of Energy's Solar Thermal Technology Program. The goal 

of this program is to advance the engineering and scientific understanding of 

solar thermal technology and to establ i sh the technology base from which 

private industry can develop solar thermal power production options for 

introduction into the competitive energy market. 

Sol ar thermal technol ogy concentrates the sol ar fl ux using tracking mirrors 

or lenses onto a receiver where the solar energy is absorbed as heat and 

converted into electricity or incorporated into products as process heat. 

The two primary solar thermal technol ogies, central receivers and distributed 

receivers, employ various point and 1 ine-focus optics to concentrate 

sun1 ight. Current central receiver systems use fields of heliostats 

(two-axis tracking mirrors) to focus the sun's radiant energy onto a single, 

tower-mounted receiver. Point focus concentrators up to 17 meters in 

diameter track the sun in two axes and use parabolic dish mirrors or Fresnel 

lenses to focus radiant energy onto a receiver. Troughs and bowls are 

line-focus tracking reflectors that concentrate sunlight onto receiver tubes 

along their focal 1 ines. Concentrating collector modules can be used alone 

or in a mu1 timodule system. The concentrated radiant energy absorbed by the 

solar thermal receiver is transported to the conversion process by a 

ci rcul ating working fl uid. Receiver temperatures range from 1000C in 

1 ow- temperature troughs to over 1500°C in di sh and central receiver systems. 

The Solar Thermal Technology Program is directing efforts to advance and 

improve each system concept through sol ar thermal material s, components, and 

subsystems research and development and by testing and evaluation. These 

efforts are carried out with the technical direction of DOE and its network 

of field laboratories that works with private industry. Together they have 

established a comprehensive, goal-directed program to improve performance and 

provide technical ly proven options for eventual incorporation into the 

Nation's energy supply. 

To successfully contribute to an adequate energy supply at reasonable cost, 

solar thermal energy must be economically competitive with a variety of other 

energy sources. The Solar Thermal Program has devel oped components and 

system-1 eve1 performance targets as quantitative program goal s. These 

targets are used in pl anni ng research and development activities, measuring 

progress, assessing a1 ternative technology options, and developing optimal 

components. These targets will be pursued vigorously to ensure a successful 

program. 

Thi s report presents the resul ts of wind-tunnel tests supported through the 

Solar Energy Research Institute (SERI) by the Office of Solar Thermal 

Technology of the U.S. Department of Energy as part of the SERI research 

effort on innovative concentrators. As gravity loads on drive mechanisms are 

reduced through stretched-membrane technology, the wind-load contribution of 

the required drive capacity increases in percentage. Reduction of wind loads 

can provide'economy in support structure and heliostat drive. Wind-tunnel 

tests have, been directed at finding methods to reduce wind loads on 

heliostats. The tests investigated primarily the mean and peak forces and 

iii 
moments. A significant increase in ability to predict peak heliostat wind 

loads and their reduction within a heliostat field was achieved. 

The work reported here was monitored by L. M. Murphy and A. Lewandowski of 

SERI. 

This report was authored by J.A. Peterka, Professor; Z. Tan, Graduate Student; 

B. Bienkiewicz, Assistant Professor; and J.E. Cermak, University Distinguished 

Professor; Fluid Mechanics and Wind Engineering Program, Fluid Dynamics and 

Diffusion Laboratory, Colorado State University, Fort Collins, Colorado. 

Approved for 

SOLAR ENERGY RESEARCH INSTITUTE 

Thermal Systems Research Branch 

7y G. C. Groff, Director 

Sol ar Heat Research Di vi si on 
The purpose of this study was to define wind load reduction factors for 

heliostats within a field of heliostats. The wind load reduction factors 

applied to both mean and peak wind loads and account for the protective 

effects of upwind heliostats, wind protective fences, or other blockage 

elements. The reason for finding methods to reduce wind loads is to improve 

the economy of heliostat support structures and drive mechanisms. These 

elements will become more sensitive to wind loads as gravity loads decrease 

through stretched membrane or other innovative technology. The method used 

in the study was to generalize wind load data obtained during tests on model 

heliostats placed in a modeled atmospheric wind in a boundary-layer wind 

tunnel. 

Previous wind-tunnel test results had shown that mean wind load decreases due 

to upwind blockage from nearby he1 iostats or wind-protective fences could be 

systematical ly accounted for with a simple 'general i zed blockage area' 

concept. In this study, the results were extended to include peak wind loads 

and to include more field geometries. In addition, results were extended to 

round as well as square shaped heliostats to demonstrate the use of the wind 

load reduction factors for stretched membrane modules. The use of porosity 

at the edge of a heliostat was investigated as a possible load reduction 

mechanism. 

Wind loads on isolated he1 iostats were determined for a range of approach 

wind turbulence intensities characteristic of those found in open-country 

environments. The results of this test were expected to show small 

variations in load with turbulence intensity. However, the drag and lift 

components showed a high and unexpected sensitivity to turbulence level when 

the heliostat was within about 45 degrees of perpendicular to the wind. 

A key finding was that heliostats in operational orientations have higher 

wind loads than for survival winds in stow position if the heliostats are 

properly oriented to the wind. A review of past wind load analyses for 

parabol ic sol ar coll ectors was made to determine whether or not additional 

measurements were required for parabolic collectors. Insufficient data for 

adequate design decisions were found. The foll owing conclusions were drawn 

from the study: 

The influence of upwind blockage of heliostats or wind fences can be 

accounted for by defining a generalized blockage area (GBA) so that the 

specific geometry may be ignored. 

Both mean and peak wind loads decrease significantly with increasing GBA 

except for very small GBA characteristic of he1 iostats in very open fields 

or of heliostats in the first two rows at the field edge. 

Wind fences at 45 degrees to the approach wind are less effective than wind 

fences perpendicul ar to the wind. Wind blockage elements (fences) whose 

length to height ratio is one or two are likely to be more effective than 

longer ones. 
Wind drag and lift on isolated heliostats have shown a surprising 

sensitivity to turbulence in the wind within the range expected for 

open-country environments. 

Square and circular heliostats have similar mean and peak wind load 

coefficients. 

Peak wind loads on operational heliostats are larger than those on 

heliostats in survival stow position provided that the heliostat in stow is 

rotated so that the elevation rotation axis points into the wind. 

Fluctuating loads about a near zero mean load in stow position may create 

fatigue loading more severe than for operational loads for some load 

components. 

He1 iostats with porous edges do not provide effective load reductions for 

either mean or peak wind loads. 

Some data in uniform flow exists for wind loads on parabolic collectors, 

but insufficient data is available for adequate design decisions. 

The fol 1 owing recommendations for future work were made: 

The effects of approach wind turbulence should be explored to determine the 

range of isolated collector load expected in typical instal lation 

environments. This recommendation is in response to the unexpected 

sensitivity to turbulence uncovered in this study. 

With resolution of the turbulence issue, a simplified design guide should 

be prepared for use in prel imi nary field design. 

Peak wind loads on flat heliostats in stow position should be examined more 

closely to determine the nature of fatigue loading. 

Mean and peak wind loads on parabolic collectors should be obtained in both 

isolated and field environments to determine differences between flat and 

parabolic shapes. 
ACKNOWLEDGEMENTS 

The authors wish to express their gratitude to the'staff and personnel of the 

Fluid Dynamics and Diffusion Laboratory at Colorado State University. 

Special thanks go to Mr. 0. Roberts, who drafted most of the illustrations 

found in this report, and Mr. D. Boyajian, who offered great assistance with 

data acquisition. Sincere gratitude is extended to Mrs. Gloria Burns for 

typing and cornpi 1 ing this report. 

Appreciation is herewith presented to the Solar Energy Research Institute 

(SERI) operated for the U. S. Department of Energy under Contract No. 

XK-6-06034-1. 
TABLE OF CONTENTS 

FOREWORD .......................... iii 

SUMMARY ........................... v 

ACKNOWLEDGEMENTS ....................... vii 

LISTOFTABLES ........................ x 

LISTOFFIGURES ....................... xi 

NOMENCLATURE ......................... xv 

1 . 0 INTRODUCTION ......................... 1 

1.1 A Review of Previous Work ................. 2 

1.2 Definition of the Generalized Blockage Area (GBA) .... 3 

1.3 Simulation of Wind Loads in the Wind Tunnel ....... 5 

2.0 EXPERIMENTAL APPARATUS AND PROCEDURES ............ 7 

2.1 The Wind Tunnel and Force Balance ............ 7 

2.2 The Models and Fences .................. 7 

2.3 The Spectra and Velocity Profiles ............ 11 

2.4 Calibration and Reynolds Number Independence ...... 13 

2.5 Test Plan ........................ 17 

2.6 Accuracy of the Data .................. 21 

3.0 DATA ACQUISITION. PROCESSING AND REDUCTION .......... 27 

3.1 Hardware Description .................. 27 

3.2 Software Routines .................... 27 

3.3 Velocity Measurements .................. 27 

3.4 Force and Moment Measurements ............... 29 

4.0 RESULTS AND DISCUSSION .................... 32 

4.1 The Single Flat Plate .................. 32 

4.2 The Flat Plate as Part of a Field ............ 37 

5.0 REVIEW OF WIND LOADS ON PARABOLIC COLLECTORS ......... 42 

6.0 CONCLUSIONS AND RECOMMENDATIONS ............... 48 

REFERENCES .......................... 50 

APPENDIX A: Plotted Results for a Single Flat Plate ..... 54 

APPENDIX B: Plotted Results for a Flat Plate as Part of 

aField ....................... 65 

viii 
Paqe 

APPENDIX C: Test Interpretation ........... 79 

C.1. Test Plan ................. 80 

C.2. CalculationofGBA ............. 89 

C.3. In-field Case as a Function of GBA Values . 95 

APPENDIX D: Output Data Files (SCT. SCTl and SCTZ) ... 108 
LIST OF TABLES 

Paqe 

Values of GBA for Test Data . . . . . . . . . . . . . . . . . 19 

Testplan--Singlestudy .................. 80 

Test Plan -- Field Study (Data Set: SCT) . . . . . . . . . . 82 

Test Plan -- Field Study (Data Set: SCT1) . . . . . . . . . 85 

Test Plan -- Field Study (Data Set: SCT2) . . . . . . . . . 87 

GBA Values for In-Field Study . . . . . . . . . . . . . . . . 9 1 

Current He1 iostat Data According to GBA (Data Set: SCT) . . . 95 

Current Heliostat Data According to GBA (Data Set: SCT1) . . 98 

Current Heliostat Data According to GBA (Data Set: SCT2) . . 100 

85 Heliostat and 78 Heliostat Data According to GBA . . . . . 102 
LIST OF FIGURES 

Fiaure 

1-1 

1-2 

1-3 

2-1 

2 . 2 

2-3 

2-4 

2-5 

2-6 

2-7 

2-8 

2-9 

2-10 

2-11 

2-12 

2-13 

2-14 

2-15 

2-16 

2-17 

2-18 

2-19 

Definition of general ized blockage area (GBA) ........ 

GBA calculation without external fence ........... 

GBA c a l c u l at ion with external fence .............. 

Industri a1 Aerodynamics Wind Tunnel. FDDL .......... 

Force andmoment balance .................. 

Square model and support column ............... 

Round model and edge-porous model .............. 

Dimensions for fences .................... 

Base moment wind load spectra for the square heliostat ... 

Base moment wind load spectra for the round heliostat .... 

Base moment wind load spectra for the edge-porous heliostat . 

Comparison between the wind tunnel 'and atmospheric spectra . 

Mean velocity and turbulence intensity profiles ....... 

Reynolds number i ndependence study ............. 

Test plan .......................... 

Definition of coordinate system ............... 

Test section of the Industrial Wind Tunnel with heliostats . 

Back view of the heliostat ................. 

Single heliostat under testing ............... 

In-field study of heliostats without fences ......... 

In-field study of heliostats with internal fences ...... 

In-field study of heliostats with both internal and external 

fences ........................... 

Flow visualization of an inclined heliostat ......... 

fl ow vi sual i zat i on of a vertical he1 i ostat ......... 

Paqe 
Fiqure 

Mean drag force coefficient variation with turbulence 

intensity .......................... 33 

Peak drag force coefficient variation with turbulence 

intensity .......................... 33 

Mean base pressure coefficient variation with turbulence 

parameter .......................... 34 

Influence of row spacing on mean drag force ......... 39 

Influence of row spacing on peak drag force ......... 39 

Influence of fences and wind angle on fourth row mean drag 

force ............................ 40 

Influence of fences and wind angle on fourth row mean hinge 

moment ........................... 40 

Influence of fences and wind angle on fourth row peak drag 

force ............................. 41 

Influence of fences and wind angle on fourth row peak hinge 

moment ........................... 41 

Comparison of LaJet collector drag with uniform flow dish 

collectors from reference 6 ................. 44 

Comparison of LaJet collector 1 ift with uniform flow dish 

collectors from reference 6 ................. 44 

Comparison of LaJet collector moment at 0 with uniform flow 

dish collectors from reference 39 .............. 45 

Comparison of LaJet collector moment at P with uniform flow 

dish collectors from reference 39 .............. 45 

Effect of a turbulent boundary layer on dish collector 

moments from reference 39 .................. 47 

Mean drag force coefficient variation with a ........ 55 

Mean lift force coefficient variation with a ........ 55 

Mean normal force coefficient variation with a ....... 56 

Mean base moment coefficient variation with a ........ 56 

Mean hinge moment variation with a ............. 57 

Mean eccentricity coefficient variation with a ....... 57 
Figure 

A-7 Mean azimuth moment coefficient at j3 = 65O .. variation 

with a ........................... 58 

Mean azimuth moment coefficient variation with /I ...... 58 

Mean drag force variation with wind direction at a = 90° . . 59 

Peak drag force coefficient variation with a ........ 59 

Peak lift force coefficient variation with a ........ 60 

Peakhingemomentcoefficientvariationwitha ....... 60 

Peak azimuth moment coefficient variation with fl ...... 61 

Mean drag force on edge-porous model ............ 61 

Mean lift force on edge-porous model ............ 62 

Mean normal force on edge-porous model . . 

Mean hinge moment on edge-porous model . . 

Peak drag force on edge-porous model ... 

Peak lift force on edge-porous model ... 

Peak hinge moment on edge-porous model . 

Mean drag force ratio in current study . 

Peak drag force ratio in current study . . 

Mean lift force ratio in current study . . 

Peak lift force ratio in current study . . 

Mean hinge moment ratio in current study . 

Peak hinge moment ratio in current study . 

Mean azimuth moment ratio in current study 

Peak azimuth moment ratio in current study 

Mean drag force ratio from previous studies 

Peak drag force ratio from previous studies 

Mean 1 ift force ratio from previous studies 

Peak lift force ratio from previous studies 
Fiqure 

B- 13 

B- 14 

B-15 

8- 16 

B- 17 

B- 18 

B-19 

B- 20 

B-21 

8-22 

B-23 

B-24 

B-25 

Mean hinge moment ratio from previous studies ...... 

Peak hinge moment ratio from previous studies ...... 

Mean drag force ratio with bounding curve ........ 

Peak drag force ratio with bounding curve ........ 

Mean lift force ratio with bounding curve ........ 

Peak lift force ratio with bounding curve ........ 

Mean hinge moment ratio with bounding curve ....... 

Peak hinge moment ratio with bounding curve ....... 

Mean azimuth moment ratio with bounding curve ...... 

Peak azimuth moment ratio with bounding curve ...... 

Summary of mean in-field to maximum mean isolated load . 

Summary of peak in-field to maximum peak isolated load . 

Wind load reduction summary for mean and peak wind loads 
NOMENCLATURE 

Symbol 

A 

Definition 

1) actual surface area, and 2) constant 

area of blockage elements projected onto a plane perpendi cul ar to approach wind direction 

field area containing blocking elements used for AB 

*fence fence sol id area 

Agross, actual ,mirror gross, actual or mirror area for edge-porous model 

Aref reference area for force and moment coefficients 

B constant 

boundary 1 ayer 

constant 

Cc~ eccentricity coefficient 

force coefficient, Fx,v,z,N 

(q(HCL) (A) 

(HCL,H) momentcoefficient, Mx,v,z,Hx,Hv 

C~x,Y,z?~x?~~ (q(HCL) (A) (HCL) 

(HCL,HCL) moment coefficient, Mx,v,z,Hx,Hv C~x,~?z,~x?~Y (q(HCL)) (A) (HCL) 

d di ameter of parabol i c col 1 ector 

D distance between EF and heliostats at the first row 

hot-wire output voltage 

external fence 

frequency, Hz 

Fx,~,z?~ measured force along axis x, y, z or heliostat 

surface normal N 

GBA 

h 

H 

generalized blockage area 

depth of parabolic collector 

he1 i ostat chord 
Svmbol 

H f 

Hrni rror 

H 0 

Hx,Hy,z 

HCL 

IF 

K 

L1 

'-2 

x 

q(HCL) 

SCT, SCT1, SCT2 

T 

Tu 

U (HCL) 

Definition 

height of external fence 

heliostat chord of mirror area for edge-porous model 

he1 iostat unit under consideration 

coordinate system at the hinge 

height of he1 iostat center1 ine (he1 iostat center) 

internal fence 

constant 

distance between heliostats in the EF direction 

distance between heliostats across EF direction 

integral length scale for turbulent flow 

reference 1 engt h 

moments for parabol i c coll ector 

measured moment about axis x, y, z, Hx and Hy 

exponent of vel oci ty prof i 1 e 

gaps between heliostat rows 

porosity of fences, fraction of total area which 

is open 

12 dynamic pressure of wind at height HCL, p U (HCL) 

data files 1 isted in Appendix D 

thickness of he1 iostat pl ate 

turbulence intensity, percent; (Urms/U) x 100 

mean wind velocity 

Reynolds number 

wind velocity at height HCL 

w~nd velocity at height z above ground 

wind velocity at reference height 

root-mean-square of vel oci ty about U 
Symbol 

Subscri~t 

mean 

peak 

rms 

ref 

Definition 

surface friction velocity 

coordinate system at the base 

height above ground 

roughness length 

elevation angle 

wind direction 

ratio of field load to isolated load for force or 

moment.component 

boundary-1 ayer thi ckness 

density of air 

kinematic viscosity 

Definition 

mean value 

peak value 

root-mean-square about mean 

reference 

xvi i 
INTRODUCTION 

An important knowledge base needed for the design and development of fields of 

tracking solar collector^ is an understanding of mean and peak wind loads 

which act on individual units within the field. This knowledge base provides 

an important input into the cost effective design of conventional 

concentrators and low-cost designs which can be less resistant to wind loads 

than conventional designs. This input can provide a basis for systems studies 

aimed at optimizing energy production per unit cost. Thus, the effects of 

collector size, component strength for resisting wind loads, field density, 

and protective wind fences can be traded during field design to produce the 

most economi cal f i el d. 

Wind loads for current heliostat designs which support the heliostat at a 

single point are particularly critical since the tracking drive system also 

must support the gravity and applied wind loads. Thus, the magnitudes of 

forces and moments at the drive/support location are important. 

Previous studies of heliostat wind loads have concentrated on measurement in a 

boundary layer wind tunnel of mean wind loads on isolated units and on units 

within a field. However, it is the peak loads which must be resisted. It is 

not evident that peak loads can be obtained by a quasi-static analysis using a 

peak gust speed in conjunction with load coefficients determined from mean 

wind and measured mean load. In this study, peak wind loads were measured 

directly. 

A need has existed for a wind load formulation for fields of heliostats which 

will permit meaningful systems studies and prel iminary field designs. This 

study has addressed that need by finding a set of load coefficient reductions 

which can be applied to a heliostat anywhere within a field and which predicts 

the reduction in wind load which is expected to occur due to protection of 

surrounding heliostats and protective wind fences. The load reduction 

coefficients were determined for both mean and peak wind loads for operational 

orientations of the he1 iostat. 

Some experiments were made in this study to extend the range of wind 

turbulence intensity to the full range expected for an open-country 

environment. The purpose was to verify that this range of turbulence intensity 

would cause only minor changes in wind load. These experiments revealed an 

unexpected sensitivity to turbulence intensity in the range of typical 

atmospheric turbulence for drag and lift forces and suggest the need for 

additional study. 

Structural failure due to wind load can be due to different mechanisms. One 

type is overstressing in which the peak stresses induced by the wind exceed 

the material capacity. Measurement of peak loads in this study provide a 

method for design against this type of failure. A second type of failure is 

fatigue in which a large number of loading cycles at less than material 

capacity can cause failure. Measurements of mean and peak loads partially 

solves that loading problem. 
A1 1 experimental measurements in thi s report are for fl at concentrator shapes. 

Parabolic concentrator shapes are expected to have somewhat different loading 

than flat plate geometries. A review of past wind load measurements is 

included in this report as a starting point for future work. 

The main purpose of this study was to investigate the mean and peak wind loads 

on a single flat plate heliostat and a heliostat in a field of similar 

structures. The intent was to determine methods for decreasing the wind loads 

on he1 iostats below those values for an isolated he1 iostat. Both mean and 

peak loads were measured in a boundary 1 ayer wind tunnel capable of. model ing 

the atmospheric boundary 1 ayer winds. No inerti a1 response of the he1 iostats 

was assumed in this study. Six load components (three forces and three 

moments) are presented in non-dimensional coefficient form: CFx, CFy, CFz, 

'MX' 'My and CH, The hinge moments (C ) and centers of pressure (C ) are MHY CP 

developed from these results. 

Wind loads on a heliostat in a field are a function of heliostat orientation, 

field density, wind direction, and the presence of wind blockage elements 

other than the heliostats themselves. The wind load on a he1 iostat fluctuates 

about a mean value due to gusting in the approach winds, due to turbulence 

generated by upwind he1 iostats or fences and due to turbulence generated in 

the wake of the he1 iostat itself. For a structure which has 1 ittle resonant 

response to the fluctuating wind load, peak design stresses will result from 

the peaks in the fluctuating wind load acting as a quasi-static load assuming 

that the bulk of the wind energy is at frequencies below the heliostat natural 

frequency. For a heliostat or collector which can undergo resonant response, 

the stresses to which the collector can be subjected will be larger than those 

induced by a quasi-static wind load since inertially driven stresses are 

present. For those cases, analysis beyond that presented herein would be 

necessary. 

1.1 A REVIEW OF PREVIOUS WORK 

The study of wind loads on ground based solar collectors has been extensive 

during recent years, [references 1 to 141. These studies include: he1 iostats 

[references 1 and 21, photovoltaic collectors [references 3, 5 to 7, and 10 to 

141 and parabolic trough collectors [references 4, 8 and 91. Some other 

re1 ated studies have investigated roof mounted collectors [references 15 to 

181 and dish antennas [references 19 to 21, and 40 to 421. Reviews of some 

previous wind load studies are given in references [22 and 391. 

The most recent study pertaining to the work in this report was performed by 

Peterka et a1 . [23] at the Fluid Dynamics and Diffusion Laboratory at Colorado 

State University. In that study, mean wind loads on heliostats within a field 

were compared to those for an isolated he1 iostat to determine load reductions 

to be expected within the field. In order to avoid~explicitly analyzing the 

1 arge number of dependent variables (he1 iostat azimuth and elevation angles, 

field 1 ayout geometry, protective wind fence geometry, and wind direction), a 

general i zed blockage area (GBA) was defined to account for a1 1 upwind bl ockage 

in a single variable. While not all possible geometries were explored, , the 

concept of .a general ized blockage area appeared to work we1 1 for mean loads. 
That report also measured some fluctuating loads -- sufficient to show that 

peak loads decreased within a field. 

The current study expands upon and extends the work of Peterka [23]. 

Additional mean load cases were studied to expand the range of conditions for 

which the GBA concept is valid and extended the study to also cover measured 

peak loads. 

1.2 DEFINITION OF THE GENERALIZED BLOCKAGE AREA (GBA) 

The general i zed bl ockage i s def i ned as fol 1 ows : 

GBA = AB/AF When the test array is deeper into the field than the 

second row or when an external fence is in place. 

As = sol id blockage area of a representative set of upwind he1 iostats 

added to the area of protective wind fences or other blockage 

elements projected onto a plane normal to the approach wind 

direction (see Figure 1-1). 

AF = the ground area occupied by the upwind blockage arrays included in 

the calculation of As. 

Special cases are: 

GBA = 0.01 When the test array is in the .first row with no external 

fence. 

G8A = 0.02 When the test array is in the second row with no external 

fence. 

Because the generalized blockage area does not work strictly for the first two 

rows without fence, values of 0.01 and 0.02 were selected arbitrarily. These 

values provided a convenient method of representing these two rows in relation 

to the interior rows. 

The definition of GBA can be simplified for the case when the external fence 

is not constructed (see Figure 1-2): 

(a) Without internal fence, 

As = the projection of the he1 iostat on to the normal to the approach 

wind direction. 

AF = the field area surrounding the arrays under consideration (see 

Figure 1-2). 

(b) With internal fence, 

AB = the projection of the heliostats and the internal fence. 

AF = field area containing two heliostats and an internal fence (see 

Figure 1-2). 
ml Internal Fence 

1-1 External Fence 

typ. I Blockage Area for Ho = A, 

Field Area (=abed) for Ho = 

A, = Blockage Area Projected on Plane Perpendicular to Wind 

of all Blockage Elements in AF 

AF = Field Areu Containing Blocking Elements Used for AB 

Unit Under Consideration, Ho 

Ho at First Row without External Fence,, GBA=O.Ol 

Ho at Second Row without External Fence, GBA=0.02 

GBA = Blockage Area AB 

/Field Area A, 

FIGURE 1-1. Definition of General i zed Bl ockage Area (GBA) 

4 
Ae = H~ COSPS~~~ 

GBA = H* cos psina/AF 

Without External 

or Internal Fence 

W'ith I'nternal Fence 

FIGURE 1-2. GBA Calcul ation Without External Fence 

A special case arises for the case of a heliostat in the first or second row 

with an external fence. In that event, the calculation of GBA is performed as 

shown in Figure 1-3. For more details refer to the example calculations in 

Appendix C-2. 

Modeling of the aerodynamic loading on a structure requires special 

consideration of flow conditions in order to obtain simil i tude between model 

and prototype. In general, the requirements are that the model and prototype 

be geometrically similar, that the approach mean velocity have a vertical 

profile shape similar to the full-scale flow, that the turbulence 

characteristics of the flows be similar, and that the Reynolds number for the 

model. and prototype be equal. 

These criteria are satisfied by constructing a scale model of the structure 

and its surroundings and performing the wind tests in a wind tunnel 

speci f ical ly designed to model atmospheric boundary-1 ayer fl ows. At 1 arge 

model scales of 190 to 1:100, some problems are encountered with exact 
model ing of the turbulence intensity. Further discussion of this issue and 

its impact on measured loads appears in following sections. 

First Row Wind 

D =Distance between EF and Heliostat 

L I =Distance between Heliostats in the 

- -- 

EF Direction 7- 

D Hf = EF Height, P = Porosity of EF 1 

GBA = 

Second Row 

L2= Distance between Heliostats -- 

Across EF Direction 

H =Side Length of Square Heliostat 

LIx Hfx(I-P)+H2cosPsina GBA = 

Ll(L2+D) 

I--LI -4 

FIGURE 1-3. GBA Calculation With External Fence 

Reynolds number similarity requires that the quantity UD/v be similar for 

model and prototype. Since v, the kinematic viscosity of air, is identical 

for both, Reynolds numbers cannot be made precisely equal with reasonable wind 

velocities. To accomplish this the air velocity in the wind tunnel would have 

to be as large as the model scale factor times the prototype wind velocity, a 

velocity which would introduce unacceptable com ressi bil i ty effects. However, 8 for sufficiently high Reynolds numbers (>2x10 ) the pressure coefficient at 

any location on the structure will be essentially constant for a arge range B of Reynolds numb rs. Typical values encountered are lo7-10 for the 

full -scale and loQ-lo6 for the wind-tunnel model. In this range acceptable 

flow similarity is achieved without precise Reynolds number equality. 
SECTION 2.0 

EXPERIMENTAL APPARATUS 

AND PROCEDURES 

2.1 ME GCIH3 TWUEL At@ FQRCE BALANCE 

This study was performed at the Fluid Dynamics and Diffusion Laboratory of the 

Engineering Research Center at Colorado State University. All the data was 

collected 'in the Industrial Wind Tunnel, Figure 2-1. 

The closed circuit, Industrial Wind Tunnel is powered by a 56 kw electric 

induction motor connected to a sixteen blade propeller. The useful mean flow 

velocity may be varied from 0.3 to 25 m/s. A flexible roof permits a boundary 

layer flow to be developed with a zero pressure gradient to approximate the 

zero pressure gradient in atmospheric flows. Roughness elements on the wind 

tunnel floor and four spires at the entrance to the working section develop a 

velocity profile comparable to that found in an open country environment. 

The force balance is a strain sensing apparatus mounted on the test section 

turntable, Figures 2-2 and 2-3. The lower strain gauges, Figure 2-2, are 

mounted in the base of the force balance and the upper gauges (see Figure 2-3) 

are mounted to the heliostat support post. Each set of gauges measures 

fluctuating moments about two horizontal and perpendicul ar axes through the 

gauge location. Differences in the moments at two elevations permit the 

forces to be obtained. Placing the upper gauges on the he1 iostat support post 

permits a more precise measurement of the hinge moment than can be obtained if 

both sets of gauges are below floor level. The vertical position of the plate 

centerline is given in this report as HCL (height of centerline = 152 mm). 

This center1 ine height represents 6.08 m if the model scale is taken as 1:40. 

The turntable was mcunted to prevent contact with the wind-tunnel walls so 

that fan induced vibrations were minimized. In this study the turntable and 

balance maintained a constant orientation to the stationary wind tunnel. 

Variations in wind direction were achieved by rotating the heliostat on the 

fixed support pole. Thus the coordinate system used was wind-fixed, not 

body-fixed. Prior to presentation, the data was rotated to a body-fixed 

coordinate system. 

A pitot-static tube was mounted 'upwind of the he1 iostat models to record the 

approach wind speed. The velocity was measured at the HCL height of 152 mm, 

the he1 iostat centerline. This velocity was used in the calculation of wind 

load coefficients. 

2.2 THE MODELS AND FENCES 

The three models shown in Figures 2-3 and 2-4 were made of 1/8 inch thick 

plywood: a square sol id plate, a round sol id plate and a square plate with 

porous edges. The sol id square plate was used in both the single and in-field 

studies. The round plate was only used for a comparison with the single, 

square plate results. Similarly the porous-edged plate was only used to 

determine the effect of porosity for the single case when compared to the 


Thicknrss of both models* 3.18 

Round Model 

Dimensions in mm 

Edge-Porous Model I 

10.0 

FIGURE 2-4. Round Model and Edge-porous Model 

solid, square plate. The vertical post in all cases was aluminum (with strain 

gauges mounted near the top) and this was attached, via a standard clamp, to a 

horizontal plexiglass rod at the back of each plate. 

Internal (wi thi n-f i eld) and external (edge-of -f i eld) fences (IF and EF) were 

made of the same material : a steel mesh with a porosity of approximately 40% 

(see Figure 2-5). A 20% change in the porosity of the fence gives a change of 

about 8% maximum in GBA value for heliostats in the 3rd row or deeper in the 

field. In the first or second row, the GBA changes in direct proportion to 

the porosity. The internal fence height was 159 mrn (0.534 of the plate 

length, H) ,and the external fence height was 240 mm (0.80 of the plate length, 

H) 
External Fence 

H: Heliostot chord 

Both fences are 40% porosity 

Internal Fence 

FIGURE 2-5. Dimensions for Fences 

2.3 THE SPECTRA AH) ELOCIn MLES 

By using a 1 ight-weight plywood material for the plates, the natural frequency 

of the balance/model combination could be kept as high as possible. 

1. The sol id, square plate had a fundamental natural frequency on the 

bal ance of 41 Hz (see Figure 2-6a). The cutoff f i 1 ter frequency was 

chosen as 32 Hz and the resulting moment spectrum in wind is shown in 

Figure 2-6b. 

2. The round plate had a fundamental natural frequency on the balance of 

53 Hz (see Figure 2-7a). The cutoff filter frequency was chosen as 

35 Hz and the resulting moment spectrum in wind is shown in Figure 

2-7b. 

3. The edge-porous, square plate had a fundamental natural frequency on 

the balance of 48 Hz (see Figure 2-8a). The cutoff filter frequency 

was chosen as 35 Hz and the resulting moment spectrum in wind is 

shown in Figure 2-8b. 

It has been shown by Cochran [24] that peak loads obtained using the frequency 

responses of Figures 2-6 to 2-8 are accurate. 

A typical velocity spectrum from the modeled atmospheric wind with no model 

present is compared, in Figure 2-9, with atmospheric spectra measured by 

Harris [34], Davenport [35] and Simiu [32]. In this case the data fits most 

closely to the function developed by Simiu. 

Two boundary layer flows were used in the wind tunnel as shown in Figure 2-10. 

Both had open-country mean velocity profile shapes with a power-1 aw exponent 

of 0.14. Both profiles also fit well to a log-law relationship with an 

effective open-country roughness length of 0.01-0.03 meters. Two turbulence 

profiles were used, one with turbulence intensities of 15-20 percent over the 

heliostat height simulating that expected in an open-country environment and 

one with lower turbulence intensities. The lower turbulence profile was 

naturally developed. The higher turbulence profile was generated using a 380 

mm high two dimensional barrier 9 m upstream from the model location. Most 

data were acquired using the lower percent turbulence intensity; only 

comparison data were acquired with the larger turbulence level. The 

implications of these profiles on the wind load data are discussed in Sections 

3.3 and 4.1. 

2.4 CALIBRATION AM) REYNOLDS NWER IWEPENDENCE 

The six electronic signals coming from the balance during testing were 

directed to an on-line data acquisition system. The balance was calibrated 

with standard loads prior to any experimental studies. The interaction 

between channels was small (4%) and linear. The channel interactions were 

small enough to ignore. The cal i bration coefficients were subsequently used 

in the data collection , program. The necessary load coefficients were 

developed using measured loads and wind velocity in a computer program 

installed in an IBM PC-XT based data acquisition system. The software 

packages are discussed in more detail in Section 3.0. 

The independence of the load coefficients to variations in Reynolds number is 

shown in Figure 2-11. The Reynolds num er independence assumption is valid 

over the range from 11.4~104 to 34.1x108. Thus the testing velocities were 

kept within the range of 6 to 18 m/s which corresponds to this range. 



Reynolds Number x lo4 

0.8 - - 

- - 

2 0.6,- - 

FIGURE 2-11. Reynolds Number Independence Study 

c 

0) .- 

0 .- 

uQQ) 

0.4- 

0.2 

0 

2.5 TEST PLAN 

* CFX 

- - CMZ 

A CMHY - 

R CFZ 

- - A A A I - - A - - 

a - - - 

- - 

I 1 I I I I I I I I 1 . 

The test program can be divided into two general areas: 

8 12 16 20 24 28 32 

1. Wind loads on an isolated heliostat. 

2. Wind loads on a heliostat as part of a field of similar structures. 

A set of generic field geometries were selected as shown in Figure 2-12. 

These field geometries were selected on the basis of previous experience in 

order to locate conditions yielding the largest loads on field he1 iostats. 

There were two row arrangements relative to the external fence used in this 

study; 0 and 45O. The O0 case gives the results when the wind approaches 

perpendicular to the rows of arrays while the other case is taken at 45O to 

the array rows (see Figure 2-12). These two directions were selected on the 

basis of previous results to define the largest loads which are likely to act 

on a heliostat in the field. The field layout geometry was generically 

similar to that used by Peterka et a1 . 1231. which used the "solar one field" 

at Barstow with variations in density of that field. These two row 

arrangements have roughly the same GBA values and exactly t.he same field 

densities, 

The fields were modified by changing the following variables: 

1. General i zed Bl ockage Area (GBA) 

GBA is a function of the physical parameters listed below. 

Calculation of GBA is shown in Section 1.2. The GBA values used in 

this study are shown in Table 2-1 to provide some intuitive feel to 

the range of values. Variables in the table are discussed below. 

TABLE 2-1. Values of GBA for Test Data 

A: 00 row arrangement, gap = N, a = 90°, /3 = o0 

B: 00 row arrangement, gap = W, a = 90°, fl = o0 

Fence 

Conf i gurat i on 

No fence 

Internal fence 

External fence 

External fence and 

Internal fence 

Row under consideration 

1 2 3 4 

0.01 0.02 0.139 0.139 

--- - - - 0.168 0.168 

0.224 0.174 0.213 0.193 

--- --- 0.235 0.225 

2. Field density without fences (row gaps of W, N, NN). 

Fence 

Configuration 

No fence 

Internal fence 

External fence 

External fence and 

Internal fence 

Field densities ranged from very open to densities typical of the 

Barstow he1 iostat field. When there is no fence present the GBA may 

be calculated using the method shown in Section 1.2. The GBA varies 

Row under consideration 

1 2 3 4 

0.01 0.02 0.070 0.070 

- - - --- 0,084 0.084 

0.224 0.110 0.122 0.106 

- - - - - - 0.135 0.124 
with field density (W,N,NN), with heliostat orientation within the 

field, and with wind direction. In this report three densities were 

studied for the case with heliostats vertical (a = 90°) and 

perpendicular to the wind (B = 0, 180°). a and /3 are defined in 

Figure 2-13. The widest (W) gap gave GBA = 0.070, the narrow (N) gap 

gave GBA = 0.139, and the narrowest gap (NN) produced GBA = 0.197 

with a = 90°, = 0, 180°. Figure 2-12 shows the use of the symbols 

W, N and NN in presenting the data. 

3. Wind direction (beta). 

Three wind directions were used in this study, 0, 20 and 45 degrees. 

Refer to Figure 2-13 for definition of B. 

X Axis at 

Y Axis 

Axis at Hinge, Hy 

Azimuth Angle) 

X Axis ot Base, x 

FIGURE 2-13. Definition of Coordinate System 

4. Tilt angle (alpha). 

Refer to Figure 2-13 for definition of the elevation angle alpha. 

5. Number of rows upstream. 

For a field with constant density, loads do not change significantly 

past the fourth row into the field. Hence, only rows 1-4 were tested 
here. For rows 1 and 2 without the external fence, the GBA is not 

effective and values of 0.01 and 0.02 were used. 

6. External fence (EF). 

The external fence was always placed at a distance two times the 

he1 iostat chord H (i .e. 2H = 0.594 m) from the first row. 

7. Internal fence (If). 

The internal fences were located at the even row numbers only; that 

is rows two, four, six, etc. 

Figure 2-12 shows the entire test plan for this study including both the 

isolated and in-field heliostats. Wind loads on the first and second rows 

were measured with and without external fences and in the narrow (N) and wide 

(W) density configurations. The third and fourth rows were tested with and 

without the internal and external fences as well as with an angular variation 

of 45O. A few runs were made with the narrow field density (NN) at an 

approach angle of OO. In the third and fourth row studies there were always 

four runs due to the combinations of internal and external fencing. 

The output data files (SCT, SCTl and SCT2) show over 400 runs and cover the 

single and in-field results. A more detailed interpretation of the results is 

presented by matrix tables in Appendix C. 

Photographs of the models in the wind tunnel are shown in Figures 2-14 to 

2-21. 

The following three areas effect the accuracy of the test results: 

1. Modeling of the wind environment. 

2. Accuracy of the instruments. 

3. Precise modeling of the heliostat and fence geometry. 

Two boundary layer simulations were used, one of which provided a more 

turbulent flow simul ation than boundary 1 ayer models used in previous studies. 

Minor changes in results were expected. The 'change in boundary layer, 

however, revealed an unexpected sensitivity to the level of turbulence 

intensity over the range of turbulence expected in the full scale. This is 

discussed more thoroughly in Section 4.1. 

The accuracy of the instruments could be effected by calibration variation and 

temperature ch.anges. The accuracy of the measurement is believed to be within 

about 5% of a representative maximum load measurement on any channel. 

The heliostat dimensions are representative of heliostats currently under 

design. Current designs are virtually sol id with no large gaps to enable a 

face-down stow position. The thickness of the heliostat as a plate was too 




1 arge in the model (3.2 mm model = 127 mm full scale at 1:40 scale) in order 

to maintain adequate model stiffness. However, since the ratio of thickness T 

to chord H is small (T/H = 0.011), the thickness is not expected to have an 

influence on measured loads. Fence porosity was set at 40 percent, in the 

middle of the 30-50 percent range which provides excellent protection with 

minimum materials. Previous work [23] showed that a berm could be effectively 

treated as a fence with no porosity for calculation of GBA. 
SECTION 3.0 

DATA ACQUISITION, 

PROCESSING AND REDUCTION 

3.1 HARDWARE DESCRIPTION 

Most data collection was performed by an IBM personal computer fitted with a 

Data Translation analog to digital converter. Only the velocity spectra and 

velocity profiles were obtained using an older Hew1 ett Packard 1000 computer 

with a Preston Scientific analogue to digital converter. 

The six signals from the high frequency force balance passed through six 

Accudata 118 amplifiers and Wavetek hi/lo filters (model number 852) to the 

IBM personal computer via an analogue to digital converter. The low-pass 

filters cut out the natural resonance of the system described in Section 2.3. 

Each channel recorded 4032 samples over a period of 40 seconds at a rate of 

about 100 Hz. From this record, mean, rms, peak maximum and peak minimum 

values on each channel were obtained. This data acquisition procedure has 

been shown, Cochran [24], to provide an adequate definition of the mean, rms 

and peak loads for a heliostat which is not in resonant response to the 

applied fluctuating load. 

"FORCA" is a data collection routine which receives signals from the force 

balance, via the electronic equipment described in Section 3.1, and then 

converts the voltages to force or moment coefficients (defined below) at a 

prescribed position on the structure. These dimensionless coefficients are 

stored in files for later inspection. 

"SETRF" is a routine that was primarily used in the cal i bration process. When 

a static, known load is applied the computer reads the voltage difference 

produced across the strain gauge bridges. Thus a plot of force or moment can 

be developed as a function of voltage. The slope of these straight 1 ines is 

then used in the load matrix of "FORCA." 

The velocity and turbulence measurements were obtained using a hot-film 

anemometer mounted on a traverse mechanism. Calibration of the hot-film 

anemometer was achieved by comparison with a pitot-static tube in the airflow 

of the Industrial Wind Tunnel. The resulting data was fitted to the King's 

law relationship: 
In Equation (3.1) E is the hot-wire output voltage, U is the wind velocity and 

A, B and C are curve fitting coefficients. During tests, the mean velocity 

was obtained from 3.1 using measured voltage and previously calculated 

cal i bration coefficients. The fluctuating velocity was obtained from: 

in which rms means root-mean-square about the mean. 

The mean velocity profile in the simulated atmospheric wind can be described 

as a power law: 

or as a logarithmic law: 

In Equation (3.3) Uref was the velocity at a height of zref = 1.016 m in the 

boundary layer (40 m full scale). The constant n describes the upwind 

roughness; n = 0.14 is typical of an open-country site. In Equation (3.4), K 

is a constant (= 0.4), zo is a roughness length dependent on upwind surface 

roughness and u* is a surface friction velocity related to the upstream 

roughness and ambient wind speed. The log law can be rewritten to relate 

velocities at one elevation to those at a reference elevation as: 

The turbulence intensity as a percent is defined as: 

The mean velocity and turbulence profiles used in this study are shown in 

Figure 2-10. Two boundary layer configurations were used, denoted by circle 

and triangle symbol s. The mean velocity profiles for both configurations 

compare well to a typical open-country profile (n = 0.14 or zo = 0.03 m) also 

plotted in the figure. Two turbulence profiles were used which had turbulence 
intensities of 10-12 percent and 17-20 percent respectively over the height 

range of the heliostats. The solid lines in the turbulence intensity plot in 

Figure 2-16 are typical values of turbulence obtained from field measurements 

for a range of open-country environments (zo = 0.01 - 0.1 meters). The 

triangle data best fit the field data. Since most previous data were obtained 

at lower turbulence levels and since the influence of turbulence was expected 

to be small, only a 1 imited amount of data was obtained at the higher 

turbulence 1 eve1 . 

The 1 ower turbul ence intensity prof i 1 e i s a naturally devel oped boundary 1 ayer 

and can be shown to correctly model an open country site at a scale of about 

1:300. The higher turbulence intensity profile was generated by install ing a 

passive turbulence generator we1 1 upstream from the model . The generator was 

experimentally tuned to obtain the appropriate turbulence level. 

Load data were acquired for a single heliostat both with the lower turbulence 

intensity of 12 percent, for comparison with previous results which typically 

used this 1 ower turbulence intensity profile, and with the higher turbulence 

level of 18 percent. Data available in the 1 iterature [38] for turbulence 

intensities up to 9 percent predicted that the difference in drag due to the 

change in profile in this experiment from 12 to 18 percent would be less than 

5 percent. Load measurements discussed below showed a much larger difference 

than the 5 percent expected. 

3.4 FORCE AND MOMENT MEASUREMENTS 

Program "FORCAf' produced the six force and moment coefficients: CFx, CFy, 

C~~, C~x Or C~~x, c~y or CHHy, and CCz. All the C's were omitted in the daia 

files for simplicity. The coefficients are defined as follows: 

The coefficient of the force along the x-axis, 

The coefficient of the force along the y-axis, 

The coefficient of the force along the z-axis, 
The coefficient of the moment about the x-axis at the base, 

The coefficient of the moment about the y-axis at the base, 

The coefficient of the moment about the z-axis, 

The coefficient of the moment about the x-axis at the hinge, 

The coefficient of the moment about the y-axis at the hinge, 

Where, 

U = reference mean velocity at hinge level at HCL = .I52 m 

above floor for model at scale of 1:40, 5.08 m in full 

scale [m/s] . 

p = air density [kg/m3]. 

Aref = reference are of 0.088 m2 $or the model at scale of 9 1:40, 141.1 m full scale [m 1. 

Lref = reference length, chord of 0.297 m at a scale of 1:40, 

11.88 m full scale [m]. 
Fx,Fy9Fz = measured forces along given axes [N]. 

Mx,My,MZ,M~x,M~y = measured moments about given axes [N.M]. 

All the moments conform to the right hand rule and the hinge moments may be 

derived from the base moments in the following manner. the relationship 

between CM~ and CMH~ is: 

In data file "SCT", MX, MY refer to CM~ and CIZ~; however, in the data files 

"SCTI" and "SCTZ, they refer to CMH~ and CMH~. 

The data files also list the gust and peak factors. The gust factor is the 

peak recorded value divided by the mean. The peak factor is the difference 

between the peak and the mean divided by the measured rms (the number of 

standard deviations from the mean). Thus the reported information given in 

each file is, in coefficient form: 

mean = time average, 

rms = root-mean-square of the fluctuating values about the mean, 

peak = largest and smallest values recorded during each 40 second 

run, 

Gust factor = peak divided by the mean, and 

Peak factor = (peak-mean)/rms . 

These factors relate to the way peak loads are often specified in code 

formulations and may be useful for later analysis related to codified formats 

of data presentation. 
SECTION 4.0 

RESULTS'AND DISCUSSION 

4.1 ME SINGLE FLAT PLATE 

The plots given in Appendix A give the available wind data for an isolated 

flat plate. The following studies are referenced: Heliostat 85 [23], 

Heliostat 78 [I], ASCE report of 1961 [36] and a NASA report [37]. The drag, 

1 ift and normal force coefficients are given as functions of the tilt angle in 

Figures A-1, A-2 and A-3. The normal force is a projection of both the drag 

and 1 ift forces to the normal taken from the plate surface: 

'Fn (HCL) = CFx (HCL) sin a t CF- (HCL) cos a . 

HCL here indicates that C was calculated using U at height HCL. The normal 

force may not precisely be equal to the resultant of the drag and lift forces 

since a small component of force may act parallel to the surface. 

The data presented in Appendix A indicates that the drag and lift forces 

measured in this study with the higher turbulence intensity are generally 

larger than in previous work. The turbulence intensity is at a more real istic 

level (18% at centerline height HCL) in the current work, whereas the 

heliostat 85 data used 14% and the heliostat 78 work used 12%. This would 

suggest that the shear flow and the turbulence intensity influence the 

resulting loads significantly. In fact, when compared to the uniform flow 

case there is an increase in the drag coefficient of more than 50% in the high 

turbulent shear flow. This is a very 1 arge change which was not expected. 

Figure 4-1 shows the variation of mean drag coefficient with turbulence 

intensity at height HCL for wind approaching perpendicular to a heliostat in 

the current study, in studies [l] and [23], and for turbulent air flow behind 

a grid in Bearman [38]. Figure 4-2 shows a similar trend for peak drag 

coefficients. This sharp increase in drag coefficient with turbulence 

intensities above 10 percent has not, to our knowledge, been previously 

documented. Integral length scale, L,, of the turbulence is included to show 

that no systematic changes are evident. Lx represents a typical length scale 

of the eddy size of the turbulent fluctuations. 

Figure 4-3 shows the influence of turbulence on drag in the form presented by 

Bearman [38]. He postulated that a turbulence parameter 

would govern the variation of base pressure (pressure on the rear face) for a 

flat plate perpendicular to a turbulent flow. Recent data from tests on 

heliostats shown in Figure 4-1 are shown on the figure. The portion of total 

drag attributable to base pressure was estimated using Bearman's data. No 

regular pattern for the data emerge from that data presentation. 

Turbulence Parameter, ( U,,,/U( z 1) ( Lx2/Aref) 

1.4- 

1.2.- 

+ 

C 

Q) 

. - 

1.0- .c 

.c 

al 

0 

0 

2 0.0.- 

3 

V) 

U) 

FIGURE 4-3. Mean Base Pressure Coefficient Variation with Turbulence 

Parameter 

I I 111111 I I 11 1111 I I 111111 

- . Uniform Flow - 

A Boundary Layer Flow (2.33)A CSU, 1987 

- 

- - 

(~.O~)ACSU, 

1985 - 

- - 

- 

- (1.85)~ CSU, 1987 - 

Data presented in Appendix A show that the int luence of turbulence in inducing 

large load increases is maximum for a vertical he1 iostat perpendicular to the 

wind. The effects decrease in magnitude as the elevation angle a decreases 

from 90 degrees. For this reason, the largest effects are seen in the drag 

force. Maximum 1 ift force is affected, but to a lesser extent since peak 1 ift 

occurs for a = 30-40 degrees. For similar reasons, maximum pitching moment 

and maximum azimuth torque are also affected less. However, all load 

components are increased due to turbulence above those predicted by uniform 

flow. 

Bearman, 1971 

- 

al (1.87)~ CSU, 1978 

In 

0 - 

a 

0.4 - 

- - 

0.2 I I 1 11 1111 I I 1 1 11 111 I I I I I Ill 

lo-* 10" lo0 10' 

Figure A-4 shows the base mome~it increase above the uniform flow case from a 

12 percent, 14 percent and 18 percent turbulence level. According to 

Bearman's data and the additional moment expected from a center-of -pressure 

shift due to the shear flow we would expect the load increase for 18 percent 

turbulence to fall about where the 12 percent data falls. The extra increase 

due to turbulence is not now explained. Design load increases above those 

predictable from Bearman's data appear to be restricted to the maximum drag 

and base moment due to drag. 
Additional study is needed to determine why the rapid increase in drag force 

occurs for turbulence intensities above 10 percent. Pertinent variables 

include turbulence intensity, integral scale of turbulence, vertical gradient 

of turbulence, vertical gradient of mean velocity, and proximity of the ground 

plane. It can be hypothesized that increased mixing in the separated shear 

layer at the heliostat edge caused by increased turbulence intensity caused a 

larger shear layer curvature and consequently a larger base pressure and drag. 

However, the reason for the sharp change in slope above 10 percent turbulence 

intensity in Figure 4-1 is not known. 

Figure A-5 shows the hinge moment data. The hinge moment peaks for an 

elevation angle of 20 to 30 degrees at a value of 0.20 to 0.25 depending on 

turbulence intensity. These values are twice the value predicted from uniform 

flow results. The effects of turbulence within the range of typical 

applications appears to be small. 

The position of center of pressure (location of resultant force) is shown in 

Figure A-6. The variation with turbulence intensity is small. The center of 

pressure is positioned above the centerline due to the shear flow which causes 

higher pressures near the top of the heliostat. 

Figures A-7 and A-8 show the mean azimuth moment coefficient (CM,). It 

appears to reach a peak between 0.2 and 0.25 when the wind angle (8) ranges 

from 60° to 70°. These load values and angles to the flow are very similar to 

those for the maximum elevation hinge moment. 

Figure A-9 presents the mean drag force (resolved normal to the plate) as a 

function of wind direction (8) for the current data set with the higher 

turbulence intensity. 

Peak loads on an is01 ated he1 iostat are shown in Figures A-10 to A-13. The 

data shows a variation with turbulence intensity similar to that for the mean 

wind loads. The largest peak loads are 2 to 3 times the value of largest mean 

loads. Peak values of 2 times the mean are consistent with gust loading from 

the approaching wind. Values much greater than two times the mean are 

consistent with gust loading augmented by wake excitation. This appears to be 

the case for the elevation and azimuth moments. In addition, the peak loads 

for these two moments are not symmetrical about the mean, an indication of 

highly correlated wake pressure fluctuations. This feature has recently been 

observed a1 so by Cochran et a1 . [24]. 

The data in A-10 to A-13 permit an examination of the relative magnitudes of 

maximum wind loads in operational orientations versus stow orientation. If we 

use 90 mph for survival stow position loads and 55 mph for maximum survivable 

operational loads in any position, then wind loads can be calculated for both 

operational and stow conditions. Comparing the ratio of peak wind loads at 

any orientation in A-10 to A-13 with those at stow (a = 0) to 1.0 will reveal 

whether operational loads are larger than stow position loads. The relevant 

peak load ratios are: 
Load Component Fx Fz MHY Mz 

Peak O~erational Load (55 m~h) 

Peak Stow Load (90 mph) 2.0 1.1 0.6 n1.0 

~oad coefficient ratios greater than 1.0 indicate that operational loads at 55 

mph are greater than stow loads at 90 mph. Only for MHy do stow loads control 

the design. However, if the heliostat were rotated in azimuth relative to the 

wind in stow position so that the elevation rotation axis aligns with the 

wind, then the MHy can be lowered below operational load maximum. This 

orientation is easily achieved with a computer-controlled field and will 

significantly reduce design loads on the elevation drive. Since the stow MHy 

loads cycle about a low or zero mean, the imp1 ications of a high cyclic load 

rate on system fatigue needs further examination. Posi tive/negative load 

cycling causes fatigue with fewer cycles than loads which cycle between values 

of the same sign. Positive/negative load cycling can be expected, for 

example, at a = 0 degrees in Figure A-12. 

An interesting feature of this study is that the round and square models 

produce very similar force and moment coefficients as shown in Figures A1-A13. 

This feature allows data obtained from earlier studies on square shapes to be 

used for circular he1 iostats. 

The results of the edge-porous study are given in Figures A-14 to A-20. 

Results are presented for an isolated heliostat for mean force coefficient 

(Figure A-14), mean 1 i ft coefficient (Figure A-15), mean normal force (Figure 

A-16) and mean elevation hinge moment (Figure A-17). Some results are 

presented for three values of reference area: the 'gross area' which includes 

the total solid area plus the area of the porosity, the 'actual area' which 

includes all solid area of the heliostat, and the 'mirror area' which is the 

solid area inside the porous edge which is suitable for a mirror surface. 

Comparison of Figure A-14 for the drag of a heliostat with a porous edge to 

that of a sol id he1 iostat in Figure A-9 shows that the porosity decreases the 

drag coefficient from about 2.1 to about 1.7 based on gross area. However, 

based on actual area, the drag coefficient increases to about 2.0. Based on 

mirror area, the drag coefficient rises to about 2.6. Thus the presence of 

porosity is a net drag producer based on a realistic energy production mirror 

area. Comparison of Figure A-17 for hinge moment with Figure A-4 shows that 

the hinge moment based on mirror area is not decreased due to presence of edge 

porosity. Peak load coefficients are presented in Figures A-18 to A-20. 

Comparison of peak loads with edge porosity to those without edge porosity 

shows that, based on the mirror area, the loads are as large or larger than 

those of a solid heliostat without porosity. It thus appears that edge 

porosity is not a beneficial addition to heliostat geometry. 

Porous edges were the only 'spoiler' concept tested in this study. 

Insufficient effort was available to test a variety of devices. It cannot be 

determined with resources available to date whether or not a spoiler exists 

which might reduce peak loads. 
4.2 THE FLAT PLATE AS PART OF A FIELD 

In these studies the influence of nearby collectors on the drag (CFx), the 

1 ift (CF,), the hinge moment (CMHy) and the azimuth moment (CMz) was studied 

in detail. The resulting load reductions for both the mean and peak loads are 

presented in Appendix B as a function of GBA. Data plotted in Appendix B is 

listed in Appendix C. In each figure of Appendix B the x-axis represents the 

general ized blockage area and the y-axis is the ratio of each component value 

(mean or peak) to the maximum value of that component found in the 

corresponding single he1 iostat study. The sing1 e-he1 iostat load used for the 

denominator of the load ratio is shown in the figure. The 12 percent 

turbulence level data were used. 

The four components noted above are presented in Figures B-1 to 8-8 in mean 

and peak plots: Figures B-1 and B-2 the mean and peak drag, Figures 8-3 and 

8-4 the mean and peak 1 ift, Figures 8-5 and 8-6 the mean and peak hinge moment 

and Figures Br7 and B-8 the mean and peak azimuth moment. 

Solid data points occur on the graphs of Appendix B. These data points 

reflect the load on a heliostat in row 1 or 2 with a fence present, but 

plotted for the GBA without the fence. These data were used in assessing the 

impact of the external fence and could otherwise be .omitted from those graphs 

without lass of content. 

Also presented in Figures B-9 to B-14 are the results from other studies such 

as Heliostat 85 [23] and Heliostat 78 [I]. The data is presented in the same 

manner; mean and peak coefficients (CFx, CFz, and dMHy). 

The old and new data were combined and an enveloping curve defined. This 

information is presented in Figures 8-15 to 8-22 and the upperbound equation 

that gives the wind load limits is given on each figure. 

All the mean load data for all load components are combined in Figure 8-23 and 

all the peak load data are combined in a similar manner in Figure 8-24. The 

merging of these two results (Figure 8-25) provides a "total wind load 

reduction curve. " 

The data and bounding curves of Appendix B show that significant reductions in 

both mean and peak wind loads result from the blockage induced by upwind 

heliostats and fences if the GBA is sufficiently high. Very open portions of 

fields such as Solar 1 at Barstow, California may have GBA values as low as 

0.1 while the dense portions may be as high as 0.25 to 0.3 based on a 

calculation without wind fences. None of the load components in Appendix B 

for either mean or peak load have a significant load reduction for GBA = 0.1. 

For GBA less than 0.1, for example in the first two rows of a field with no 

wind fences, the load may be higher than that of an isolated heliostat. For a 

GBA of 0.25, a fairly easily obtained value if wind fences are included or if 

the heliostats are fairly tightly packed, the load may be reduced by 20 

percent for peak drag force, by 65 percent for peak hinge moment, and by 80 

percent for peak azimuth moment. 

The load reduction charts of Appendix B used the maximum isolated heliostat 

load associated with a 12 percent turbulence intensity. This was done because 
all in-field studies were performed at a 12 percent turbulence intensity. The 

load reduction curves might be somewhat different in an 18 percent turbulence 

intensity environment. However, since the drag force is the only component 

which is highly sensitive to turbulence intensity, only the load reduction 

charts for drag may change significantly. It is expected that the load on a 

heliostat at a GBA of 0.2 to 0.25 would be fairly insensitive to approach 

turbulence since the 1 ocal in-fie1 d turbulence intensity generated by upwind 

heliostats is quite high. Thus, use of the curves with a drag value for 

turbulence of 12 percent for an isolated he1 iostat for any approach wind will 

give a correct answer for GBA - 0.2 regardless of the actual approach 

conditions. For GBA - 0.1, the reduction in load may not be completely 

dominated by local turbulence, and use of the 18 percent turbulence drag 

coefficient for an isolated he1 iostat might be more appropriate and would be 

conservative. Additional study is recommended to resolve this issue, since 

the use of the lower isolated drag coefficient may, in fact, give a reasonable 

result in this case. 

The next step in use of the curves of Appendix B is to construct a users guide 

which simplifies as much as possible the use of the data. Such a guide is 

planned and is in development. 

The external fence is a critical mechanism to the reduction of first and 

second row he1 iostat loads. The load reduction from an external fence is less 

significant in the third row and not apparent for rows further back than 

number four. This result is confirmed by the Heliostat 85 data [23]. 

The impact of decreasing row spacing for rows near the edge of the field with 

an external fence is shown in Figures 4-4 and 4-5. These figures show that 

the mean and peak wind loads decrease with increasing GBA (decreased row 

spacing) and increase with distance from the fence. The reason for the 

increase with distance from the fence is that the region immediately behind 

the fence is better ~rotected than areas farther from the fence (interior to 

the field) where the external fence is not effective in providing protection. 

For very dense fields this effect would not occur. 

Figures 4-6 through 4-9 show the influence of internal and external fences on 

wind loads in row 4 for various combinations of row spacing and approach wind 

direction. The important conclusions from these figures are that closer row 

spacing is beneficial (increased GBA) and that flow crossing a fence at 45 

degrees to the fence is less effective than flow crossing perpendicular to a 

fence. 

All of the effects shown in Figures 4-4 through 4-9 are included in the load 

reduction charts of Appendix B. Further research into effects such as 

improving the protective influence of a fence at 45 degrees to the wind flow 

might enable a further decrease in load in the position of the bounding load 

reduction curves. 



SECTION 5.0 

REVIEW OF WIND LOADS 

ON PARABOLIC COLLECTORS 

The bluff geometry of parabolic concentrators results in complex flow patterns 

which are impossible to predict analytically. As with flat collectors, 

experimental results are used to provide data necessary for prediction of the 

wind-induced aerodynamic loads on and responses of the collectors. The data 

is based on wind-tunnel and full-scale experiments. In most cases only the 

wind-tunnel data is available. 

The scope of available data related to wind loading on three-dimensional 

parabol i c col 1 ectors i s rather ' 1 imi ted. Parabol i c troughs and trough field 

arrays have been studied in a simulated atmospheric boundary layer [8], but 

the majority of wind loading data for three-dimensional parabolic reflectors 

were obtained from model studies on radio antennas [39]. Most of the earlier 

theoretical and experimental studies were performed for i sol ated (single) 

reflectors in uniform non-turbulent flows. As shown earlier in this report, 

the lack of turbulence and shear in the approach flow can seriously 

underpredict wind loads on collectors in a real atmospheric wind. 

Wind-tunnel data for parabolic antenna models were presented by Blaylock et 

a1 . [40]. Models with different surface porosities (uniform porosity ranging 

from zero to 50 percent and edge-only porosity) and various depth-to-diameter 

ratios were tested. The overall aerodynamic forces and moments were measured 

for various orientations of the antenna model relative to the approach flow. 

Only the mean (static) loads were reported. Most of the tests were conducted 

in uniform flow. 

The results presented in reference 1401 included the sensitivity of the 

aerodynamic data to changes in such parameters as: the center of rotation of 

the antenna, the depth-to-diameter ratio, the surface porosity, edge spoilers, 

support structure, ground plane interference. The effects of the atmospheric 

velocity profile were evaluated through a series of tests in 1/7th power-law 

boundary-layer profile. No turbulence characteristics such as intensity, 

spectra, or scale were reported for these shear flow tests so that it is not 

possible to determine how well the flow modeled the atmospheric boundary 

layer. The influence of the boundary layer in these tests was small, a 

possible indication of too low a turbulence intensity. 

Use of data of [40] for wind loading specifications for prototype parabolic 

reflectors is limited due to the fact that most of the data was extracted in a 

uniform flow. Also, the data obtained in boundary-layer flow should be 

treated with caution. Therefore extrapolation of the model data to prototype 

conditions cannot be made without significant uncertainties. 

Wind effects on parabolic antennas were also analyzed by Cohen and Vellozzi 

[41]. Their study was limited to an analysis of static effects. The authors 

synthesized earl ier experimental results for parabol ic antennas, obtained for 

small models in uniform flow. They summarized the effects of several design 

parameters (depth-to-diameter ratio, surface sol idi ty ratio, detai 1 s of 
surface geometry) on mean aerodynamic. forces and moments. The effects were 

discussed for the operational ranges of the altitude and azimuth angles. 

The experimental data was supplemented by theoretical analysis for pressure 

distribution and lift coefficient for antenna at low angles of attack. A 

potential flow theory developed for a circular arc and flat plate was extended 

and used to estimate pressure distribution and lift coefficient for a 

parabolic (sol id and porous) reflector. For higher angles of attack, 

empirical relations were proposed by the authors. The agreement between the 

theoretical predictions and the experimental data was not satisfactory; 

however, trends in the results were similar and the agreement was improved by 

adjustments in the theoretical results to account for viscous effects and flow 

separation. 

The authors also discussed in some detail ground effects and shielding effects 

for a parabolic reflector. Based on the data for the effects of ground 

proximity on aerodynamic characteristics of rectangular cambered wings of low 

aspect ratio, they conducted that the ground effects for a solid circular 

reflector in a vertical position should be negligible for gap-to-diameter 

ratio greater than 0.35. (The gap is the minimum distance from the reflector 

to the ground.) Limited experimental data was also used to estimate. the 

shielding effects by an upwind reflector. An empirical relation was proposed 

for the shielding factor downstream of a reflector of porosity equal to or 

higher than 0.20. 

The presented data did not address the effects of the boundary-layer flow 

approaching the refl ectors. Only static wind effects were analyzed. These 

constraints limit the application of the presented data in design of prototype 

parabol ic sol ar coll ectors. 

A recent discussion [39] of uniform flow wind-tunnel results for parabolic 

refl ectors suggests the foll owing observations: 

1. The minimum drag occurs at zero angle of attack. It increases with the 

depth-to-di arneter ratio. 

2. Maximum lift occurs at a positive angle of attack of 30 degrees. The lift 

is low and directed upwards for negative angles of attack. 

3. Support structures generally have a tendency to reduce peak loads. 

A wind-tunnel study has been performed at CSU on a LaJet parabolic collector 

in a turbulent boundary layer flow which modeled atmospheric winds [42]. A 

comparison of these data with uniform flow data on parabolic collectors was 

made as part of this study. Differences were expected because of the large 

porosity of the LaJet collector and due to the presence of turbulence and 

shear in the wind flow. 

The results of the comparison of LaJet data with uniform flow data are given 

in Figures 5-1 to 5-4. These figures show drag, 1 ift, and moments about two 

locations for two sets of data: (1) a summary of uniform flow. lift, drag and 

moment obtained from pages 13-38 and 13-39 of Roschke [39], and (2) data from 

reference [42] which lists data for turbulent boundary layer flow for the 

LaJet collector. Data were converted to the coordinate reference system used 


by Roschke for convenience. The reference area used in the coefficients was 

based on a circle with diameter of the LaJet collector at the midpoint of the 

six flat sides bounding the periphery of the collector and with 1/6 of the 

area removed to account for the missing 1/6 sector of the collector (called 

slot in the figures). Porosity was ignored in calculating collector area, 

since porosity is not always effective in reducing loads by the fraction of 

porosity existing and because estimated area of the supporting truss work 

accounted for more than half of the area represented by porosity. The 

variable h/d in the figures represents depth of collector dish h divided by 

the diameter d. This value was about 0.1 for the LaJet collector. 

Several factors contribute to differences between the LaJet collector of 

reference [42] and the collectors of reference [39]: one set is porous, one 

solid; one set has a slot, the other none; one set was tested in a turbulent 

boundary layer, the other in a uniform, non-turbulent flow. The differences 

in load coefficients in Figures 5-1 to 5-4 can be attributed to these 

differences. The increase in drag coefficient of Figure 5-1 for the LaJet 

data indicates increase .in drag due to turbulence, although uncertainty in 

applicable reference area is of the same size as differences in drag 

coefficient. 

In Figure 5-2, the apparent good agreement between data sets for a > 0 is the 

result of two factors influencing the LaJet collector: increased turbulence 

is expected to increase lift while the collector porosity should adjust 

pressure distributions across the surface in a way which should decrease lift. 

The cancellation of these effects leaves the data essentially unchanged from 

the uniform flow case. For a c 0, balancing forces at opposite rims in the 

uniform flow case are disrupted in the LaJet case resulting in a significantly 

higher lift. In Figures 5-2 to 5-4, + and - local pressure indications 

near the lips are labeled with U for uniform flow or P for porous. The 

speculated changes in the local pressure distribution from one case to the 

other can provide an explanation of differences between the data sets. These 

local pressure indications are conjecture based on experience and has no basis 

in actual local pressure measurements. 

The moment comparisons of Figures 5-3 and 5-4 show large variations between 

uniform flow and the LaJet data. The LaJet data above 0.25 in moment 

coefficient are due in major part to the shift in center of pressure caused by 

the missing sector in the slot down configuration. Filling the slot or 

turning it to the side caused a dramatic decrease in moment. Other 

differences between uniform flow and LaJet data can be explained by 

conjectured local pressure distribution differences as shown by drawings on 

the figures. The overall precision of the measurements of the LaJet data is 

much better than the general scatter of LaJet data. Dif'ferences in geometry 

between the various LaJet configurations is sufficient to cause this. 

The difference which might be expected between two identical solid dish 

collectors placed in uniform or turbulent boundary layer flow is difficult to 

assess from the comparisons shown above. An indication of the differences 

might be provided by the one equivalent comparison shown by Roschke on pages 

13-37, reproduced here as Figure 5-5. The differences shown are modest; 

however, the modeled boundary layer was not developed over a long fetch and 

its ability to duplicate atmospheric turbulence effects has not been 

establ i shed. 
OUTER 25% OF RADIUS HAS 25% POROSITY 

h/D=0.149 Re(dia)=2xl& 

COEFFICIENT REFERENCED TO VELOCITY AT 

REFLECTOR CENTER HEIGHT 

AZIMUTH ANGLE FROM WIND, deg 

FIGURE 5-5. Effect of a Turbulent Boundary Layer on Dish 

Col 1 ector Moments from Reference 39 

The conclusion from the foregoing analysis of parabolic collectors is that 

uniform flow results increased by 10-20 percent may be a valid starting point 

for load estimation for solid disks in an atmospheric boundary layer. 

However, changes in geometry to the disk (or support structure) may cause 

large and unpredictable variations from the uniform flow case. Systematic 

studies of dish coll ectors in an atmospheric boundary layer flow are needed to 

define isolated collector loads and to determine the influence of nearby 

collectors in a field. 
SECTION 6.0 

CONCLUSIONS AND 

RECOMMENDATIONS 

In this study, fluctuating wind loads on model heliostats were obtained in a 

boundary layer wind tunnel capable of simulating wind flows at model scale. 

Based on data presented, the following conclusions can be drawn: 

The influence of upwind blockage of heliostats or wind fences can be 

accounted for by. defining a general ized blockage area (GBA) so that the 

specific geometry may be ignored. 

Both mean and peak wind loads decrease significantly with increasing GBA 

except for very small GBA, characteristic of heliostats in very open 

fields, or of heliostats in the first two rows at the field edge. 

Wind fences at 45 degrees to the approach wind are less effective than wind 

fences perpendicular to the wind. Wind blockage elements (fences) which do 

not represent a long continuous fence may be more effective than a single 

1 ong fence. 

Wind drag and lift on isolated heliostats have shown a surprising 

sensitivity to turbulence in the wind within the range expected for 

open-country environments. 

Square and circular he1 iostats have similar mean and peak wind load 

coefficients. 

Peak wind loads on operational heliostats are larger than those on 

he1 iostats in survival stow position provided that the he1 iostat in stow is 

rotated so that the axis of elevation rotation points into the wind. 

Fluctuating loads about a near zero mean load in stow position may create 

fatigue loading more severe than for operational loads for some load 

components. This result is based on conjecture and not on experimental 

measurements in this study. 

He1 iostats with porous edges do not provide effective load reductions for 

either mean or peak wind loads. 

Some data in uniform flow exists for wind loads on parabolic collectors, 

but insufficient data is avail able for adequate design decisions. 

On the basis of the data and the conclusions presented herein, the following 

recommendations for further work are set forth: 

The effects of approach wind turbulence should be explored to determine the 

range of isolated collector load expected in typical installation 

environments. This recommendat ion is in response to the unexpected 

sensitivity to turbulence uncovered in this study. 
With resolution of the turbulence issue, a simplified design guide should 

be prepared for use in prel iminary field design. 

Peak wind loads on flat heliostats in stow position should be examined more 

closely to determine the nature of fatigue 1 oading. 

Mean and peak wind loads on parabol ic col lectors should be obtained in both 

is01 ated and field environments to determine differences between fl at and 

parabol i c shapes. 

Research to improve the effectiveness of wind fences oriented 45 degrees to 

approach winds might reduce the loads on he1 iostats in a field below those 

reported herein. 
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APPENDIX A 

Plotted Results for a Single Flat Ylate 










APPENDIX B 

Plotted Results for a Flat Plate as Part of a Field 













APPENDIX C 

Test Interpretat i on 

C.1. Test Plan 

C.2. Calculation of GBA 

C.3. In-field Case as a Function of GBA Values 
C. 1. TEST PLAN 

TABLE. C-1-1. Test Plan -- Single Study 

(Comment: Repeated run numbers don't mean they are the same run.) 

Postscripts F, B, L, R, see Figure 2-12 

Square Model Round Model Edge-porous Model 

Run # ct /I Run # a B Run # a 

Data File: SCTl 

Data File: SCT2 
TABLE. C-1-1. Test Plan -- Single Study (con't) 

(Comment: Repeated run numbers don't mean they are the same run.) 

Postscripts F, B, L, R, see Figure 2-12 

Square Model Round Model Edge-porous Model 

Run # a fl Run # a fl Run # a fl 
TABLE. C-1-2~. Test Pl an -- Field Study 

Key = Row Arr., Degree (0 and 45 degrees) ; Gap: W, N, NN; 

Row #: 1, 2, 3, 4 

(Refer to Section 2.5 and Figure 2-12) 

1. Data File: SCT 

Run # Row Arr. Gap Row # a /I EF IF 
TABLE. C-1-ZA. Test Plan -- Field Study (con't) 

Key = Row Arr., Degree (0 and 45 degrees); Gap: W, N, NN; 

Row #: 1, 2, 3, 4 

(Refer to Section 2.5 and Figure 2-12) 

1. Data File: SCT 

Run # Row Arr. Gap Row # cr B EF IF 
TABLE. C-1-ZA. Test Plan -- Field Study (con't) 

Key = Row Arr., Degree (0 and 45 degrees) ; Gap: W, N, NN; 

Row #: 1, 2, 3, 4 

(Refer to Section 2.5 and Figure 2-12) 

1. DataFile: SCT 

- 

Run # Row Arr. Gap Row # a fl EF IF 
TASLE. C-1-28. Test Plan -- Field Study 

Key = Row Arr., Degree (0 and 45 degrees); Gap: W, N, NN; Row #: 1, 2, 3, 4 

(Refer to Section 2.5 and Figure 2-12) 

2. Data File: SCTl 

Run # Row Arr. Gap Row # a p EF IF 
TABLE. C-1-28. Test Plan -- Field Study (con't) 

Key = Row Arr. , Degree (0 and 45 degrees) ; Gap: W, N, NN; 

Row #: 1, 2, 3, 4 

(Refer to Section 2.5 and Figure 2-12) 

2. Data File: SCTl 

Run # Row Arr. Gap Row # a fl EF IF 
TABLE. C-1-2~. Test Plan -- Field Study (con't) 

Key = Row Arr . , Degree (0 and 45 degrees) ; Gap: W, N, NN; 

Row #: 1, 2, 3, 4 

(Refer to Section 2.5 and Figure 2-12) 

3. Data File: SCT2 

Run # Row Arr. Gap Row # a #? EF IF 
TABLE. C-1-2~. Test Plan -- Field Study (con't) 

Key = Row Arr., Degree (0 and 45 degrees) ; Gap: W, N, NN; 

Row #: 1, 2, 3, 4 

(Refer to Section 2.5 and Figure 2-12) 

3. Data File: SCT2 

Run # Row Arr. Gap Row # a j EF IF 
C.2. clUUATION OF GBA 

Examples of calculation of GBA (a = 90, B = 0). Fence porosity is 40%. 

EF height is 0.8H, while IF height is 0.534H. For this section, refer to the 

test plan and Figure 2-12. 

A. Third row at O0 row arrangement (N) . 

1. Without EF, without IF 

2 H sin a! cos B - H~ 

GBA = 3.07H x 2.34H -3.07H x 2.34H = 0.139 

2. Without EF, with IF 

2 

GBA = 2H + 1.32H X 0.534H X 60% = 0*168 

2.34 x 2 x 3.07H 

3. With EF, without IF 

r) 

4. With EF, with IF 

2 

GBA = 3H + 2.34H x 0.8H x 60% + 1.32H x 0.534H x 60% = 00.235 

2.34H x (2 x 3.07H t 2.14H) 

B. Fourth row at 45' row arrangement (N) 

1. Without EF, without IF 

H~ 

GBA = 3.07H x 2.34H = 0.139 

2. Without EF, with IF 

2 

GBA = 2H + 1.32H x 0.534H x 60% = 0.168 

2.34H x 2 x 3.07H 

3. With EF, without IF 

The field from EF is 4.87 m long - 16.4H 

2 

GBA = 14H + 6.15H x 0.8H x 60%=0.168 

16.4H x 6.15H ' 
4. With EF, with IF 

GBA = 14~~ + 6.15H x 0.8H x 0.6 + 1.32H x 0.534H x 60% x 5 x cos 45' 

16.4H x 6.15H 

= 0.183 
TABLE C-2-1. GBA Values for In-Field Stlidy 

Row Arr. Gap Row # Q fl EF IF GBA 
TABLE C-2-1. GBA Values for In-Field Study (con't) 

-- - - -- - -- 

Row Arr. Gap Row # a l? EF IF G BA 
TABLE C-2-1. GBA Values for In-Field Study (con't) 

. - -- 

Row Arr. Gap Row # a B EF IF GBA 
TABU C-2-1. GBA Values for In-Field Study (con't) 

Row Arr. Gap Row # a fl EF IF GBA 
C.3. IN-FEU) CASE AS A FWTION OF 68A VALUES 

TABLE C-3-k. Current He1 iostat Data According to GBA 

1. Data File: SCT 

Run # GBA 
TABLE C-3-h. Current Heliostat Data According to GBA (con't) 

1. Data File: SCT 

Run # GBA 
TABLE C-3-h. Current He1 iostat Data According to GBA (con't) 

1. Data File: SCT 

Run # GBA %x 7~z 7~~~ : 'FX peak 7~z oeak 
TABLE C-3-le. Current He1 iostat Data According to GBA 

2. Data File: SCTl 

Run # 
TABLE C-3-IB. Current He1 iostat Data According to GBA (con't) 

2. Data File: SCTl 

Run a # GBA 7~x 7~z 'MHY 7~x peak r~z oeak r~~v peak 

243 0.143 0.375 0.810 0.602 0.508 1.017 0.. 637 

244 0.095 0.321 0.673 0.494 0.457 0.875 0.636 

245 0.070 0,296 0.370 0.398 0.351 0.533 0.318 

246 0.119 0,326 0.450 0.395 0.448 0.813 0.415 

247 0.143 0.283 0,284 0.398 0.361 0.495 0.344 

248 0.095 0.208 0.190 0.300 0.228 0.166 0.217 

250 0.131 0.626 0.171 0.065 0,997 0.332 0.290 

251 0.180 0.710 0.144 0.054 0,914 0.310 0.305 

252 0.204 0.745 0.410 0.069 0.947 0.337 0.321 

253 0.156 0.660 0.166 0.080 0.889 0.340 0.362 
TABLE C-3-lc. Current He1 iostat Data According to GBA 

3. DataFile: SCT2 

Run # GBA 
TABU C-3-lc. Current He1 iostat Data According to GBA (con't) 

3. .Data File: SCT2 

Run # GBA 7~z r~z oeak 
TA~E C-3-2. 85 Heliostat and 78 He1 iostat Data According to GBA 

Note: Coefficient values are as defined in refs. 23 and 1, 

not as in this report. 

85 He1 iostat: Maximum values in single study in ref. 23 

Mean : CFx = 1.72 CFz = 1.11 'MH~ = 0.16 

Peak: 'FX peak = 2.56 'FZ peak = 'MH~ peak = 0.62 

78 Heliostat: Maximum values in single study in ref. 1 

Mean : FX = 1.38 CMHy = 0.215 

Config. a B GBA YFx Y~z r~~v Y~x ~eak Y~z oeak 'MHV oeak 

H5000 80 5.0 0.138 0.426 0.089 0.750 0.707 0.095 0.790 

80 5.0 0.138 0.262 0.013 0.438 0.352 0.048 0.419 

70 2.5 0.132 0.361 0.127 0.375 0.480 0.156 , 0.548 

90 5.0 0.140 0.328 0.025 0.438 0.590 0.177 0.097 
TABLE C-3-2. 85 He1 iostat and 78 He1 iostat Data According to GBA (con't) 

Note: Coefficient values are as defined in refs. 23 and 1, 

not as in this report. 

85 Heliostat: Maximum values in single study in ref. 23 

Mean : 

Peak: 'FX peak = 2*56 peak = 'MH~ peak = 0.62 

78 Heliostat: Maximum values in single study in ref. 1 

Mean : 

Conf i g . a B GBA 7Fx y~z 7~~v 'FX ~eak 7~z ~eak 7~~v oeak 

H3200 90 0.0 0.245 0.115 0.000 0.063 0.410 0.068 

90 0.0 0.245 0.107 0.000 0.063 0.281 0.075 

90 0.0 0.245 0.107 0.025 0.125 0.359 0.048 

90 0.0 0.245 0.098 0.013 0.000 0.293 0.068 

90 0.0 0.245 0,107 0.013 0.000 0.238 0.048 

90 0.0 0.245 0.131 0.025 0.063 0.375 0.082 

90 0.0 0.245 0.156 0.025 0.000 0.320 0.068 

90 0.0 0.245 0,123 0.013 0.063 0.328 0.054 
TABLE C-3-2. 85 He1 iostat and 78 He1 iostat Data According to GBA (con't) 

Note: Coefficient values are as defined in refs. 23 and 1, 

not as in this report. 

85 He1 iostat: Maximum values in single study in ref. 23 

Mean : FX = 1.72 CFz = 1.11 'MH~ = 0.16 

Peak: 'FX peak = 2.56 'FZ peak = 1.47 'MHY peak = 0.62 

78 He1 iostat: Maximum values in single study in ref. 1 

Mean : CFx = 1.38 CMHy = 0.215 

Config. a I? GBA 7~x IFZ 7~~v 7~x oeak oeak 'MHV oeak 

H3502 90 00.0 0.179 0.180 0.013 0.063 0.445 0.061 

Hel. 85 80 00.0 0.010 1.020 0.825 1.750 0.961 0.660 0.806 

0.010 0.186 0.126 0.690 0.543 0.218 0.645 

Hel. 78 10 00.0 0.029 0.096 0.721 

30 00.0 0.084 0.331 0.591 

90 00.0 0.168 0.555 0.140 

10 00.0 0.029 0.111 0.400 

10 00.0 0.024 0.093 0.420 

90 00.0 0.136 0.544 0.116 
TABU C-3-2. 85 Heliostat and 78 Heliostat Data According to GBA (con't) 

Mean : 

Note: Coefficient values are as defined in refs. 23 and 1, 

not as in this report. 

85 Heliostat: Maximum values in single study in ref. 23 

Peak: 'Fx peak = 2*56 'FZ peak = *47 'MH~ peak = 0.62 

78 Heliostat: Maximum values in single study in ref. 1 

Mean : 

Config. a I? GBA r~x 7~z 7~~v r~xoeak 'FZ aeak ~MHV oeak 

H5001 80 85.0 1 

(con't) 80 72.5 ( 

80 50.0 ( 

80 27.5 ( 
TABLE C-3-2. 85 He1 iostat and 78 He1 iostat Data According to GBA (con't) 

Note: Coefficient values are as defined in refs. 23 and 1, 

not as in this report. 

85 Heliostat: Maximum values in single study in ref. 23 

Mean : CFx = 1.72 CFz = 1.11 'MHy = 0.16 

Peak: 'FX peak = 2'56 'FZ peak = 1.47 'MH~ peak = 0.62 

78 Heliostat: Maximum values in single study in ref. 1 

Mean : CFx = 1.38 CMHy = 0.215 

Config. a B GBA r~x r~z ~MHY 7~x oeak 7~z oeak 7~~~ oeak 

H5001 65 50.0 0.128 0.025 0.050 0.063 0.441 0.184 

65 27.5 0.159 0.254 0.175 0.188 0.512 0.238 

65 25.0 0.161 0.393 0.225 0.063 0.617 0.293 

65 20.0 0.165 0.295 0.175 0.063 0.512 0.252 

65 42.5 0.140 0.361 0.213 0.063 0.531 0.224 
TMU C-3-2. 85 He1 iostat and 78 He1 iostat Data According to GBA (con't) 

Note: Coefficient values are as defined in refs. 23 and 1, 

not as in this report. 

85 Heliostat: Maximum values in single study in ref. 23 

Mean : 'FX = 1.72 CF, = 1.11 C~~y = 0.16 

Peak: 'FX peak = 2e56 'FZ peak 'MH~ peak = 0.62 

78 He1 iostat: Maximum values in single study in ref. 1 

Mean : CFx = 1.38 CMHY = 0.215 
APPENDIX D 

Output Data Files (SCT, SCTl and SCT2) 
Data File: SCT 

For Field Study 

In the file labelled "SCT" the coefficient denoted by "MX" and "MY" are the 

base moment coefficients. However, in the files labelled "SCTI" and "SCTZ" 

the coefficient of "MX" and "MY" are the hinge moment coefficients about the 

y-axis at the motor drive level. 

Comments: 1. Because of system lift force, FZ actual = F, - 0.273 

(e.g. F, = 0.529 (Run # 13), F, actual = 0.529 - 0.273 = 0.256) 

2. MY is the base moment coefficient, C in data file: SCT MY 
RUN # WIND TILT VELOCITY COMP: FX F Y F z MX MY MZ 

13 .O 90.0 9.2 Mean 

Max 

Mi n 

Rms 

G FAC 

PFAC 

14 .O 90.0 9.3 Mean 

Max 

Mi n 

Rms 

GFAC 

P FAC 

.O 90.0 9.2 Mean 

Max 

Mi n 

Rms 

G FAC 

PFAC 

.O 90.0 9.3 Mean 

Max 

Mi n 

Rms 

GFAC 

PFAC 

2 1 .O 90.0 9.2 Mean 

Max 
RUN # WIND TILT VELOCITY COMP: FX FY FZ MX MY MZ 

Min 

Rms 

GFAC 

PFAC 

.O 90.0 9.2 Mean 

Max 

Min 

Rms 

GFAC 

PFAC 

Mean 

Max 

Min 

Rms 

GFAC 

PFAC 

Mean 

Max 

Mi n 

Rms 

GFAC 

PFAC 

Mean 

Max 

Mi n 

Rms 
RUN # WIND TILT VELOCITY COMP: F X F Y F Z MX MY MZ 

G FAC 

PFAC 

2 6 .O 90.0 9.2 Mean 

Max 

Mi n 

Rms 

G FAC 

P FAC 

.O 30.0 9.3 Mean 

Max 

Mi n 

Rms 

GFAC 

P FAC 

.O 30.0 9.3 Mean 

Max 

Mi n 

Rms 

G FAC 

P FAC 

.O 30.0 9.2 Mean 

Max 

Mi n 

Rms 

GFAC 

P FAC 
RUN # WIND TILT VELOCITY COMP: FX FY FZ MX MY MZ 

30 .O 30.0 9.2 Mean 

Max 

Mi n 

Rms 

GFAC 

PFAC 

Mean 

Max 

Mi n 

Rms 

GFAC 

PFAC 

Mean 

Max 

Mi n 

Rms 

GFAC 

PFAC 

.O 30.0 9.2 Mean 

Max 

Mi n 

Rms 

GFAC 

PFAC 

34 .O 30.0 9.2 Mean 

Max 
- 

RUN # WIND TILT VELOCITY COMP: FX F Y FZ MX MY MZ 

Mi n 

Rms 

GFAC 

PFAC 

.O 30.0 9.3 Mean 

Max 

Mi n 

Rms 

GFAC 

PFAC 

.O 30.0 9.3 Mean 

Max 

Mi n 

Rms 

GFAC 

PFAC 

.O 30.0 9.1 Mean 

Max 

Mi n 

Rms 

GFAC 

PFAC 

38 .O 30.0 9.3 Mean 

Max 

Mi n 
RUN # WIND TILT VELOCITY COMP: FX FY FZ MX MY MZ 

Rms 

GFAC 

PFAC 

.O 30.0 9.1 Mean 

Max 

Mi n 

Rms 

GFAC 

PFAC 

. 0 30.0 9.1 Mean 

Max 

Mi n 

Rms 

GFAC 

PFAC 

.O 90.0 9.1 Hean 

Max 

Mi n 

Rms 

GFAC 

PFAC 

.O 90.0 9.2 Mean 

Max 

Min 

Rms 

GFAC 

PFAC 
RUN # WIND TILT VELOCITY COMP: FX FY FZ MX MY MZ 

43 .O 90.0 9.2 Mean 

Max 

Mi n 

Rms 

GFAC 

P FAC 

4 4 .O 90.0 9.1 Mean 

Max 

Mi n 

Rms 

G FAC 

PFAC 

.O 90.0 9.2 Mean 

Max 

Mi n 

Rms 

G FAC 

PFAC 

.O 90.0 9.0 Mean 

Max 

Mi n 

Rms 

GFAC 

PFAC 

47 .O 90.0 8.9 Mean 

Max 
- -- - 

RUN # WIND TILT VELOCITY COMP: FX FY FZ MX MY MZ 

Mi n 

Rrns 

G FAC 

PFAC 

90.0 9.2 Mean 

Max 

Mi n 

Rms 

GFAC 

PFAC 

30.0 9.2 Mean 

Max 

Min 

Rms 

G FAC 

PFAC 

30.0 8.9 Mean 

Max 

Mi n 

Rms 

GFAC 

PFAC 

30.0 9.0 Mean 

Max 

Mi n 

Rms 
RUN # WIND TILT VELOCITY COMP: 

GFAC 

PFAC 

52 .O 30.0 9.3 Mean 

Max 

Mi n 

Rms 

GFAC 

P FAC 

.O -30.0 9.2 Mean 

Max 

Mi n 

Rms 

G FAC 

PFAC 

.O -30.0 9.0 Mean 

Max 

Mi n 

Rms 

GFAC 

P FAC 

.O -30.0 9.0 Mean 

Max 

Mi n 

Rms 

GFAC 

PFAC 
- - 

RUN # WIND TILT VELOCITY COMP: FX FY FZ MX MY MZ 

56 .O -30.0 9.2 Mean 

Max 

Mi n 

Rms 

GFAC 

PFAC 

57 20.0 90.0 9.0 Mean 

Max 

Min 

Rms 

GFAC 

PFAC 

CI 

w 

CD 

58 20.0 90.0 9.1 Mean 

Max 

Mi n 

Rms 

G FAC 

PFAC 

59 20.0 90.0 9.0 Mean 

Max 

Mi n 

Rms 

GFAC 

PFAC 

60 20-0 90.0 9.2 Mean 

Max 
- - - 

RUN # WIND TILT VELOCITY COMP: F X FY FZ MX MY MZ 

Mi n 

Rms 

GFAC 

PFAC 

6 1 20.0 90.0 9.1 Mean 

Max 

Mi n 

Rms 

GFAC 

P FAC 

6 2 45.0 90.0 9.2 Mean 

w Max N 

0 

Mi n 

Rms 

GFAC 

PFAC 

63 45.0 90.0 9.1 Mean 

Max 

Mi n 

Rms 

GFAC 

PFAC 

64 45.0 90.0 9.0 Mean 

Max 

Mi n 
RUN # WIND TILT VELOCITY COMP: FX F Y FZ MX MY MZ 

Rms 

G FAC 

PFAC 

65 45.0 90.0 9.1 Mean 

Max 

Mi n 

Rrns 

G FAC 

PFAC 

.O 90.0 9.2 Mean 

Max 

Min 

Rms 

G FAC 

PFAC 

.O 90.0 9.1 Mean 

Max 

Min 

Rms 

G FAC 

PFAC 

.O 90.0 9.1 Mean 

Max 

Mi n 

Rms 

GFAC 

PFAC 
RUN # WIND TILT VELOCITY COMP: FX FY FZ MX MY MZ 

69 .O 90.0 9.1 Mean 

Max 

Mi n 

Rms 

GFAC 

PFAC 

70 .O -30.0 9.3 Mean 

Max 

Mi n 

Rms 

GFAC 

PFAC 

7 1 .O -30.0 9.1 Me an 

Max 

Mi n 

Rms 

G FAC 

PFAC 

7 2 .O -30.0 9.2 Mean 

Max 

Mi n 

Rms 

GFAC 

PFAC 

7 3 .O -30.0 9.2 Mean 

Max 
-- - - - -- 

RUN # WIND TILT VELOCITY COMP: FX FY FZ MX MY MZ 

Mi n 

Rms 

GFAC 

PFAC 

.O 30.0 9.2 Mean 

Max 

Mi n 

Rms 

GFAC 

PFAC 

.O 30.0 9.2 Mean 

Max 

Mi n 

Rms 

GFAC 

PFAC 

.O 30.0 9.2 Mean 

Max 

Mi n 

Rms 

GFAC 

PFAC 

.O 30.0 9.2 Mean 

Max 

Min 

Rms 
RUN # WIND TILT VELOCITY COMP: FX F Y F Z MX MY MZ 

G FAC 

PFAC 

78 .O 90.0 9.1 Mean 

Max 

Mi n 

Rms 

G FAC 

PFAC 

7 9 20.0 90.0 9.0 Mean 

Max 

Mi n 

Rms 

GFAC 

P FAC 

80 20.0 90.0 9.2 Mean 

Max 

Mi n 

Rms 

G FAC 

PFAC 

81 20.0 90.0 9.2 Mean 

Max 

Mi n 

Rms 

G FAC 

P FAC 
- -- -- -- 

RUN # WIND TILT VELOCITY COMP: FX FY FZ MX MY MZ 

90.0 9.1 Mean 

Max 

Mi n 

Rms 

GFAC 

PFAC 

90.0 9.2 Mean 

Max 

Mi n 

Rrns 

GFAC 

PFAC 

90.0 9.1 Mean 

Max 

Mi n 

Rms 

GFAC 

PFAC 

90.0 9.2 Mean 

Max 

Mi n 

Rms 

G FAC 

PFAC 

-30.0 9.3 Mean 

Max 
DATA FILE: SCT 

-- -- - 

RUN # WIND TILT VELOCITY COMP: F X F Y F Z MX MY MZ 

Mi n 

Rms 

G FAC 

PFAC 

30.0 9.3 Mean 

Max 

Mi n 

Rms 

GFAC 

PFAC 

88 .O -30.0 9.3 Mean 

c1 Max N 

QI 

Mi n 

Rms 

G FAC 

PFAC 

89 .O -30.0 9.2 Mean 

Max 

Mi n 

Rms 

G FAC 

PFAC 

90 .O -30.0 9.2 Mean 

Max 

Mi n 

Rms 

G FAC 

PFAC 
- - - - 

RUN # WIND TILT VELOCITY COMP: FX FY FZ MX MY MZ 

91 .O -30.0 9.2 Mean 

Max 

Mi n 

Rms 

GFAC 

PFAC 

92 . 0 -30.0 9.1 Mean 

Max 

Mi n 

Rms 

GFAC 

PFAC 

93 .O -30.0 9.3 Mean 

Max 

Mi n 

Rms 

GFAC 

PFAC 

94 .O -30.0 9.2 Mean 

Max 

Mi n 

Rms ' 

GFAC 

PFAC 

95 .O -30.0 9.3 Mean 

Max 
RATA FILE: SCT 

- - 

RUN # WIND TILT VELOCITY COMP: FX F Y FZ MX MY MZ 

Mi n 

Rms 

G FAC 

P FAC 

.O -30.0 9.3 Mean 

Max 

Mi n 

Rms 

G FAC 

PFAC 

.O -30.0 9.3 Mean 

Max 

Mi n 

Rms 

G FAC 

PFAC 

.O -30.0 9.2 Mean 

Max 

Mi n 

Rms 

G FAC 

PFAC 

.O -30.0 9.2 Mean 

Max 

Mi n 

Rms 

G FAC 

PFAC 
RUN # WIND TILT VELOCITY COMP: FX FY FZ MX MY MZ 

100 .O -30.0 9.2 Mean 

Max 

Mi n 

Rms 

GFAC 

PFAC 

.O -30.0 9.2 Mean 

Max 

Mi n 

Rms 

G FAC 

PFAC 

.O 30.0 9.2 Mean 

Max 

Mi n 

Rms 

GFAC 

PFAC 

0 30.0 9.2 Mean 

Max 

Mi n 

Rms 

GFAC 

PFAC 

104 .O 30.0 9.3 Mean 

Max 
- 

RUN # WIND TILT V~!LOCITY COMP: FX F Y FZ MX MY MZ 

Mi n 

Rms 

G FAC 

PFAC 

.O 30.0 9.2 Mean 

Max 

Mi n 

Rms 

G FAC 

PFAC 

.O 90.0 9.2 Mean 

Max 

Mi n 

Rms 

G FAC 

PFAC 

.O 90.0 9.2 Mean 

Max 

Mi n 

Rms 

GFAC 

PFAC 

108 .O 90.0 9.0 Mean 

Max 

Mi n 

Rms 
RUN # WIND TILT VELOCITY COMP: FX FY FZ MX MY MZ 

G FAC 2.280 2.755 1.373 2.496 2.476 6.495 

PFAC 4.431 4.137 3.668 4.728 4.989 3.820 

Mean 

Max 

Mi n 

Rms 

GFAC 

PFAC 

Mean 

Max 

Mi n 

Rms 

G FAC 

PFAC 

Mean 

Max 

Mi n 

Rms 

G FAC 

PFAC 

Mean 

Max 

Min 

Rms 

G FAC 

PFAC 
RUN # WIND TILT VELOCITY COMP: 

113 20.0 90.0 9.0 Mean 

Max 

Mi n 

Rms 

G FAC 

PFAC 

114 20.0 90.0 9.1 Mean 

Max 

Mi n 

Rms 

GFAC 

PFAC 

C, 

0 

N 115 45.0 90.0 9.1 Mean 

Max 

Mi n 

Rms 

GFAC 

PFAC 

116 45.0 90.0 9.1 Mean 

Max 

Mi n 

Rms 

G FAC 

P FAC 

117 45.0 90.0 9.1 Mean 

Max 
- - - -- - 

RUN # WIND TILT VELOCITY COMP: FX FY FZ MX MY MZ 

Mi n 

Rms 

GFAC 

PFAC 

9.3 Mean 

Max 

Mi n 

Rms 

GFAC 

PFAC 

9.2 Mean 

Max 

Min 

Rms 

GFAC 

PFAC 

9.1 Mean 

Max 

Mi n 

Rrns 

GFAC 

PFAC 

121 .O 90.0 9.2 Mean 

Max 

Mi n 

Rms 
RUN # WIND TILT VELOCITY COMP: FX F Y F Z MX MY MZ 

GFAC 3.421 2.730 1.293 2.674 3.394 6.983 

PFAC 4.834 4.734 3.130 4.846 4.707 4.267 

122 .O 90.0 9.3 Mean .550 .050 .505 - ,030 .299 .029 

Max 1.896 .I34 .674 :O 14 .960 .238 

Mi n -. 131 - .038 .338 - .077 - .061 - .095 

Rms .266 .024 .046 .011 .I44 .037 

G FAC 3.447 2.693 1.333 2.552 3.209 8.306 

PFAC 5.064 3.574 3.631 4.117 4.574 5.575 

123 .O 80.0 9.1 Mean .527 .063 .508 - .034 .285 .025 

Max 2.023 .136 .700 .€I15 1.104 ,138 

Mi n - .081 - .028 ,201 - .089 - .038 -. 130 

Rms .244 .022 .061 .013 ,135 .033 

G FAC 3.841 2.168 1.378 2.618 3.874 5.609 

PFAC 6.127 3.378 3.119 4.183 6.057 3.494 

124 .O 80.0 9.2 Mean .421 .058 .562 - .030 .223 .029 

Max 1.519 .I12 ,732 .007 .786 .174 

Mi n -. 100 - .007 .369 - .080 - ,065 - .088 

Rms .206 .017 .053 .010 .I14 .032 

GFAC 3.608 1.938 1.302 2.664 3.523 6.135 

PFAC 5.342 3.227 3.201 5.007 4.920 4.572 

125 .O 80.0 9.1 Mean .377 .060 .517 - .028 .I99 .028 

Max 1.266 .lo8 .685 .003 .729 .I39 

Mi n - ,056 .002 .295 - .077 - .052 - .082 

Rms .I81 .015 .055 .009 .lo0 .027 

G FAC 3.357 1.799 1.326 2.703 3.664 5.037 

PFAC 4.903 3.176 3.074 5.371 5.307 4.109 
- - 

RUN # WIND TILT VELOCITY COMP: FX FY FZ MX MY MZ 

126 .O 80.0 9.1 Mean . 444 .045 .462 -. 027 .233 .020 

Max 1.444 .I25 ,650 ,024 .785 .I78 

Mi n -. 108 - ,032 .237 - .083 - -062 -. 106 

Rms .216 .020 .060 ' .012 .I19 .031 

GFAC 3.250 2.763 1.408 3.034 3.362 8.759 

PFAC 4.620 4.052 3.123 4.588 4,621 5.161 
Data File: SCTl 

For Si ngl e Square Model 

In the file labelled "SCT" the coefficient denoted by "MX" and "MY" are the 

base moment coefficients. However, in the files labelled "SCT1" and "SCT2" 

the coefficient of "MX" and "MY" are the hinge moment coefficients about the 

y-axis at the motor drive level. 

Comments: 1. Because of system lift force, F, actual = F, - 0.160 

(e.g. F, = 0.353 (Run # 254), F, actual = 0.353 - 0.160 = 0.193) 

2. MY is the hinge moment coefficient, C in data file: SCTl MHY 
RUN # WIND TILT VELOCITY COMP: FX FY FZ MX MY MZ 

254 .O 90.0 9.3 Mean 

Max 

Mi n 

Rms 

G FAC 

PFAC 

.O 75.0 9.5 Mean 

Max 

Mi n 

Rms 

G FAC 

PFAC 

.O 60.0 9.6 Mean 

Max 

Mi n 

Rms 

GFAC 

PFAC 

Mean 

Max 

Mi n 

Rms 

G FAC 

PFAC 

258 .O 30.0 9.6 Mean 

Max 
RUN # WIND TILT VELOCITY COMP: FX F Y F Z MX MY MZ 

Mi n 

Rms 

G FAC 

PFAC 

20.0 9.4 Mean 

Max 

Mi n 

Rms 

G FAC 

P FAC 

10.0 9.4 Mean 

Max 

Mi n 

Rms 

G FAC 

PFAC 

.O 9.5 Mean 

Max 

Mi n 

Rms 

G FAC 

PFAC 

.10.0 9.1 Mean 

Max 

Mi n 

Rms 
RUN # WINO TILT VELOCITY COMP: FX FY FZ MX MY MZ 

GFAC 

PFAC 

.O -20.0 9.4 Mean 

Max 

Min 

Rms 

GFAC 

PFAC 

.O -30.0 9.3 Mean 

Max 

Mi n 

Rms 

GFAC 

PFAC 

-. 0 -45.0 9.4 Mean 

Max 

Mi n 

Rms 

GFAC 

PFAC 

. 0 -60.0 9.3 Mean 

Max 

Mi n 

Rms 

G FAC 

PFAC 
RUN # WIND TILT VELOCITY COMP: FX FY FZ MX MY MZ 

267 .O -75.0 9.4 Mean 

Max 

Mi n 

Rms 

G FAC 

PFAC 

268 .O -90.0 9.4 Mean 

Max 

Mi n 

Rms 

GFAC 

PFAC 
Data File: SCTl 

For Sing1 e Round Model 

In the file labelled "SCT" the coefficient denoted by "MX" and "MY" are the 

base moment coefficients. However, in the files labelled "SCTl" and "SCT2" 

the coefficient of "MX" and "MY" are the hinge moment coefficients about the 

y-axis at the motor drive level. 

Comments: 1. Because of system lift force, FZ actual = F, - 0.200 

(e.g. F, = 0.411 (Run # 270), F, actual = 0.411 - 0.200 = 0.211) 

2. MY is the hinge moment coefficient, CMHy in data file: SCTl 
RUN # WIND TILT VELOCITY COMP: F X FY FZ MX MY MZ 

270 .O 90.0 9.4 Mean 

Max 

Mi n 

Rms 

G FAC 

PFAC 

.O 75.0 9.5 Mean 

Max 

Mi n 

Rms 

G FAC 

PFAC 

.O 60.0 9.4 Mean 

Max 

Mi n 

Rms 

GFAC 

P FAC 

.O 45.0 9.5 Mean 

Max 

Mi n 

Rms 

GFAC 

PFAC 

274 .O 30.0 9.6 Mean 

Max 
RUN # WIND TILT VELOCITY COMP: FX FY FZ MX MY MZ 

Mi n 

Rms 

GFAC 

PFAC 

Mean 

Max 

Min 

Rms 

GFAC 

PFAC 

Mean 

Max 

Min 

Rms 

GFAC 

PFAC 

Mean 

Max 

Mi n 

Rms 

GFAC 

PFAC 

278 .O -10.0 9.6 Mean 

Max 

Mi n 

Rms 
RUN # WIND TILT VELOCITY COMP: FX F Y F Z MX MY MZ 

G FAC 

PFAC 

279 .O -20.0 9.3 Mean 

Max 

Mi n 

Rrns 

G FAC 

PFAC 

280 .O -30.0 9.6 Mean 

Max 

Mi n 

cI Rms 

P 

P GFAC 

PFAC 

281 .O -45.0 9.4 Mean 

Max 

Mi n 

Rms 

G FAC 

PFAC 

282 .O -60.0 9.5 Mean 

Max 

Mi n 

Rms 

G FAC 

PFAC 
RUN # WIND TILT VELOCITY COMP: FX FY FZ MX MY MZ 

283 .O -75.0 9.6 Mean 1.819 .207 .889 .014 ,040 ,052 

Max 3.742 ,372 1,429 .068 .270 .310 

Mi n .664 .lo1 474 - ,041 -. 144 - .090 

Rrns .476 ,040 .I34 01 2 .050 -050 

GFAC 2.057 1.796 1.608 4.862 6.798 5.977 

PFAC 4.040 4.157 4,026 4.432 4.643 5.207 

.O -90.0 9.5 Mean 1.918 .223 .508 .Ole .023 .055 

Max 3 , 843 .398 .775 .036 ,259 .250 

Mi n .718 .099 .264 .002 - ,126 - 153 

Rms .499 ,043 .085 ,005 .046 .055 

GFAC 2.004 1.784 1.524 2.217 11.317 4.539 

PFAC 3.859 4.021 3.123 4.124 5.183 3.554 
Data File: SCTl 

For Si ngl e Edge-porous Model 

In the file labelled "SCT" the coefficient denoted by "MX" and "MY" are the 

base moment coefficients. However, in the files labelled "SCT1" and "SCT2" 

the coefficient of "MX" and "MY" are the hinge moment coefficients about the 

y-axis at the motor drive level. 

Comments: 1. Because of system lift force, FZ actual = Fz - 0.160 

(e.g. FZ = 0.332 (Run # 271), F, actual = 0.332 - 0.160 = 0.172) 

2. MY is the hinge moment coefficient, C in data file: SCTl MHY 
- -- 

RUN # WIND TILT VELOCITY COMP: FX FY FZ MX MY MZ 

90.0 9.6 Mean 

Max 

Mi n 

Rms 

GFAC 

PFAC 

Mean 

Max 

Mi n 

Rms 

GFAC 

PFAC 

Mean 

Max 

Mi n 

Rms 

GFAC 

PFAC 

Mean 1,098 ,176 - .578 

Max 2.357 .370 .I63 

Mi n ,376 .059 -1.577 

Rms ,313 .040 -284 

GFAC 2.147 2.100 2.727 

PFAC 4.019 4.806 3.516 

275 .O 30.0 9.5 Mean ,756 .I56 - .627 

Max 1,608 .352 .279 
- - - -- 

RUN # WIND TILT VELOCITY COMP: FX FY F Z MX MY MZ 

Mi n 

Rms 

G FAC 

P FAC 

20.0 9.2 Mean 

Max 

Mi n 

Rms 

G FAC 

P FAC 

10.0 9.5 Mean 

Max 

Mi n 

Rms 

GFAC 

PFAC 

.O 9.6 Mean 

Max 

Mi n 

Rms 

G FAC 

PFAC 

10.0 9.3 Mean 

Max 

Mi n 

Rms 
RUN # WIND TILT VELOCITY COMP: FX FY FZ MX MY MZ 

GFAC 

PFAC 

.O -20.0 9.8 Mean 

Max 

Mi n 

Rrns 

GFAC 

PFAC 

.O -30.0 9.2 Mean 

Max 

Mi n 

Rrns 

G FAC 

PFAC 

.O -45.0 9.5 Mean 

Max 

Mi n 

Rrns 

G FAC 

PFAC 

.O -60.0 9.4 Mean 

Max 

Mi n 

Rms 

GFAC 

PFAC 
RUN # WIND TILT VELOCITY COMP: FX F Y F Z MX MY MZ 

284 .O -75.0 9.4 Mean 

Max 

Mi n 

Rms 

GFAC 

PFAC 

285 .O -90.0 9.5 Mean 

Max 

Mi n 

Rms 

G FAC 

PFAC 
Data File: SCTl 

For Field Study 

In the file labelled "SCT" the coefficient denoted by "MX" and "MY" are the 

base moment coefficients. However, in the files labelled "SCT1" and "SCT2" 

the coefficient of "MX" and "MY" are the hinge moment coefficients about the 

y-axis at the motor drive level. 

Comments: 1. Because of system 1 ift force, FZ actual = Fz - 0.160 

(e.g. F, = -0.630 (Run # 197), F, = -0.630 - 0.160 

2. MY is the hinge moment coefficient, CMHy in data file: SCTl 
-- 

RUN # WIND TILT VELOCITY COMP: FX FY FZ MX MY MZ 

197 .O 30.0 10.1 Mean .629 .I47 - .630 .026 - .I33 .019 

Max .940 .239 - .I79 .093 - .068 .071 

Mi n .384 ,046 -1.140 - .034 -.217 - .030 

Rms .070 .025 -124 .016 .021 .012 

GFAC 1.495 1.630 1.811 3.591 1.627 3.739 

PFAC 4.415 3.698 4.119 4.153 3.891 4.414 

.O 30.0 9.7 Mean .669 .I79 - ,694 .030 -.I26 .021 

Max 1.293 .363 - .033 .I60 - .005 .lo0 

Mi n ,292 .063 -1.668 - .098 - .299 - .072 

Rms .!49 .036 .243 .028 .036 .020 

G FAC 1.933 2.028 2.404 5.328 2.365 4.732 

PFAC 4.194 5.078 4.014 4.586 4.740 3.931 

.O 30.0 9.7 Mean .569 .164 - .442 .025 -.I26 .014 

Max 1.123 ,332 .I44 .142 - .019 .090 

Mi n .223 .047 -1.324 - .085 - .333 - .057 

Rms .I40 .035 .224 .028 .038 .019 

G FAC 1.974 2.032 2.994 5.601 2.649 6.427 

PFAC 3.972 4.841 3.938 4.143 5.406 3.950 

.O 30.0 9.9 Mean ,510 .127 - .393 .021 -.I15 .008 

Max .900 .266 - .046 .094 - .043 .054 

Mi n .295 .059 -1.043 - .065 - .256 - .058 

Rms ,078 .024 .I35 .019 .023 .014 

GFAC 1.765 2.103 2.651 4.453 2.221 6.643 

PFAC 5.008 5.850 4.812 3.756 6.063 3.383 

201 .O -30.0 9.9 Mean .512 .079 1.154 .024 .I65 ,020 

Max 1.033 .I93 1.793 .I77 .362 .090 
RUN # WIND TILT VELOCITY COMP: FX FY FZ MX MY MZ 

Mi n 

Rms 

GFAC 

PFAC 

202 .O -30.0 9 . 8 Mean 

Max 

Mi n 

Rms 

GFAC 

PFAC 

203 .O -30.0 9.7 Mean 

Max 

Min 

Rms 

G FAC 

PFAC 

204 .O -30.0 10.0 Mean 

Max 

Mi n 

Rms 

GFAC 

PFAC 

205 .O -30.0 10.0 Mean 

Max 

Mi n 

Rms 
RUN # WIND TILT VELOCITY COMP: FX FY FZ MX MY MZ 

GFAC 

PFAC 

.O -30.0 10.0 Mean 

Max 

Mi n 

Rms 

GFAC 

PFAC 

.O -30.0 10.0 Mean 

Max 

Mi n 

Rms 

G FAC 

PFAC 

.O -30.0 10.0 Mean 

Max 

Mi n 

Rms 

G FAC 

PFAC 

.O 30.0 9.9 Mean 

Max 

Mi n 

Rms 

G FAC 

PFAC 

- - -- 

RUN # WIND TILT VELOCITY COMP: F X F Y F Z MX MY MZ 

Mi n 

Rms 

GFAC 

P FAC 

.30.0 10.1 Mean 

Max 

Mi n 

Rms 

G FAC 

PFAC 

30.0 10.0 Mean 

Max 

Mi n 

Rms 

G FAC 

P FAC 

90.0 9.9 Mean 

Max 

Mi n 

Rms 

G FAC 

PFAC 

30.0 10.0 Mean 

Max 

Mi n 

Rms 
-- 

RUN # WIND TILT VELOCITY COMP: FX FY FZ MX MY MZ 

GFAC 

PFAC 

.O -30.0 10.1 Mean 

Max 

Min 

Rms 

GFAC 

PFAC 

.O 30.0 10.0 Mean 

Max 

Min 

Rm s 

GFAC 

PFAC 

.O 30.0 9.9 Mean 

Max 

Min 

Rms 

G FAC 

PFAC 

.O 30.0 10.0 Mean 

Max 

Min 

Rms 

GFAC 

PFAC 
RUN # WIND TILT VELOCITY COMP: F X F Y FZ MX MY MZ 

223 .O 30.0 10.0 Mean 

Max 

Mi n 

Rms 

GFAC 

PFAC 

.O 90.0 10.0 Mean 

Max 

Mi n 

Rms 

G FAC 

PFAC 

.O 90.0 9.9 Mean 

Max 

Mi n 

Rms 

G FAC 

PFAC 

.O 90.0 9.9 Mean 

Max 

Mi n 

Rms 

GFAC 

PFAC 

227 .O 90.0 9.9 Mean 

Max 
RUN # WIND TILT VELOCITY COMP: FX FY FZ MX MY MZ 

Mi n 

Rms 

G FAC 

PFAC 

.O 90.0 10.1 Mean 

Max 

Mi n 

Rms 

G FAC 

PFAC 

. 0 90.0 9.9 Mean 

Max 

Min 

Rms 

G FAC 

PFAC 

.O 90.0 10.0 Mean 

Max 

Mi n 

Rms 

GF4C 

PFAC 

231 .O 90.0 10.0 Mean 

Max 

Mi n 

Rms 
RUN # WIND TILT VELOCITY COMP: FX FY FZ MX MY MZ 

232 .O 30.0 10.0 Mean 

Max 

Mi n 

Rms 

G FAC 

PFAC 

GFAC 2.379 2.031 1.460 2.273 14.485 5.938 

PFAC 4.268 4.176 3.134 4.841 5.723 3.824 

.O 30.0 10.1 Mean 

Max 

Mi n 

Rms 

G FAC 

PFAC 

.O 30.0 10.0 Mean 

Max 

Mi n 

Rms 

G FAC 

PFAC 

0 30.0 10.2 Mean 

Max 

Mi n 

Rrns 

GFAC 

PFAC 

RUN # WIND TILT VELOCITY COMP: F X FY FZ MX MY MZ 

237 .O -80.0 10.0 Mean 

Max 

Mi n 

Rms 

G FAC 

PFAC 

.O -80.0 9.9 Mean 

Max 

Mi n 

Rms 

G FAC 

PFAC 

.O -80.0 10.0 Mean 

Max 

Mi n 

Rms 

G FAC 

PFAC 

.O -80.0 10.0 Mean 

Max 

Mi n 

Rms 

G FAC 

PFAC 

241 .O -30.0 10.1 Mean 

Max 
RUN # WIND TILT VELOCITY COMP: FX FY FZ MX MY MZ 

Mi n 

Rms 

GFAC 

PFAC 

0 -30.0 10.0 Mean 

' Max 

Min 

Rms 

GFAC 

PFAC 

0 -30.0 9.9 Mean 

Max 

Min 

Rms 

G FAC 

PFAC 

.O -30.0 10.0 Mean 

Max 

Mi n 

Rms 

GFAC 

PFAC 

245 .O 30.0 10.1 Mean 

Max 

Mi n 

Rrns 
RUN # WIND TILT VELOCITY COMP: FX FY FZ MX MY MZ 

G FAC 

PFAC 

246 .O 30.0 10.0 Mean 

Max 

Mi n 

Rms 

GFAC 

PFAC 

247 .O 30.0 10.0 Mean 

Max 

Mi n 

Rms 

G FAC 

PFAC 

.O 30.0 10.0 Mean 

Max 

Mi n 

Rms 

GFAC 

PFAC 

2 50 20.0 90.0 10.0 Mean 

Max 

Mi n 

Rms 

G FAC 

PFAC 
RUN # W~ND TILT VELOCITY COMP: FX FY FZ MX MY MZ 

251 2-0 . 0 90.0 10.0 Mean 1.130 .466 .331 -014 -014 - .054 

Max 2.226 .886 ,527 ,058 ,202 .I37 

Mi n ,322 ,191 ,120 - .039 - .I35 - .251 

Rms .274 .099 .072 .012 -043 ,049 

G FAC 1.971 1,902 1.594 4.269 14.472 4.660 

PFAC 3 995 4.240 2.746 3.583 4.391 4.010 

252 20.0 90.0 9.9 Mean 

Max 

Mi n 

Rms 

G FAC 

PFAC 

c.' 

m 

~n 253 20.0 90.0 9.9 Mean 

Max 

Mi n 

Rms 

G FAC 

PFAC 
Data File: SCT2 

For Single Square Model 

In the file labelled "SCT" the coefficient denoted by "MX" and "MY" are the 

base moment coefficients. However, in the files labelled "SCT1" and "SCT2" 

the coefficient of "MX" and "MY" are the hinge moment coefficients about the 

y-axis at the motor drive level. 

Comment: MY is the hinge moment coefficient, C in data file: SCT2 MHY 

RUN # WIND TILT VELOCITY COMP: FX FY FZ MX MY MZ 

8 .O 90.0 9.6 Mean 

Max 

Mi n 

Rms 

G FAC 

PFAC 

9 10.0 90.0 9.6 Mean 

Max 

Mi n 

Rms 

G FAC 

P FAC 

w 

0, 

cn 

10 20.0 90.0 9.9 Mean 

Max 

Mi n 

Rms 

G FAC 

P FAC 

11 30.0 90.0 9.5 Mean 

Max 

Mi n 

Rms 

G FAC 

PFAC 

12 40.0 90.0 9.7 Mean 

Max 
RUN # WIND TILT VELOCITY COMP: FX FY FZ MX MY MZ 

Mi n 

Rms 

G FAC 

PFAC 

13 50.0 90.0 9.8 Mean 

Max 

Mi n 

Rms 

G FAC 

PFAC 

8 55.0 90.0 9.9 Mean 

Max 

Mi n 

Rms 

GFAC 

PFAC 

14 60.0 90.0 9.7 Mean 

Max 

Mi n 

Rms 

GFAC 

PFAC 

9 65.0 90.0 9.8 Mean 

Max 

Mi n 

Rms 
- -- 

RUN # WIND TILT VELOCITY COMP: FX F Y F Z MX MY MZ 

GFAC 

PFAC 

15 70.0 90.0 9.7 Mean 

Max 

Mi n 

Rms 

GFAC 

PFAC 

5 4 75.0 90.0 9.9 Mean 

Max 

Mi n 

Rms 

GFAC 

PFAC 

3 80.0 90.0 9.9 Mean 

Max 

Mi n 

Rrns 

G FAC 

PFAC 

5 85.0 90.0 10.0 Mean 

Max 

Mi n 

Rms 

G FAC 

PFAC 
RUN # WIND TILT VELOCITY COMP: FX FY FZ MX MY MZ 

4 90.0 90.0 9.6 Mean .I51 .I65 .013 ,008 ,003 .074 

Max .404 2.376 .141 .I91 -074 .476 

Mi n -.056 -1,122 -. 184 - .I88 - ,049 - .476 

Rms .067 .407 .040 .044 ,013 ,122 

G FAC 2.670 14.439 10.973 25.275 23.252 6,446 

PFAC 3.776 5.430 3.189 4.174 5.325 3.293 

LEFT RIGHT 

FRONT /d 

Single Heliostat 

u 

, 
- - - - - -- - - -p 

RUN # WIND TILT VELOCITY COMP: FX FY F Z MX MY MZ 

10 .O 90.0 9.7 Mean 2.045 .087 - .074 .014 ,008 .053 

Max 4.107 .315 .033 ,038 ,214 .354 

Mi n .495 - ,059 - .199 - .006 - .I58 - .280 

Rms .584 .040 ,033 .007 .051 .069 

G FAC 2.008 3.629 2.683 2.695 28.572 6.656 

PFAC 3.528 5.764 3.725 3.610 4.040 4.335 

10.0 90.0 9.7 Mean 

Max 

Mi n 

Rms 

GFAC 

P FAC 

25.0 90.0 9.8 Mean 

Max 

Mi n 

Rms 

G FAC 

PFAC 

45.0 90.0 9.7 Mean 

Max 

Mi n 

Rms 

G FAC 

PFAC 

14 50.0 90.0 9.7 Mean 

Max 
- 

RUN # WIND TILT VELOCITY COMP: FX FY FZ MX MY MZ 

Mi n 

Rms 

G FAC 

PFAC 

55.0 90.0 9.7 Mean 

Max 

Min 

Rrns 

G FAC 

PFAC 

60.0 90.0 10.1 Mean 

Max 

Mi n 

Rms 

GFAC 

PFAC 

65.0 90.0 9.9 Mean 

Max 

Min 

Rms 

G FAC 

PFAC 

70.0 90.0 9.4 Mean 

Max 

Mi n 

Rms 
-- - 

RUN # WIND TILT VELOCITY COMP: F X F Y F Z MX MY MZ 

GFAC 

PFAC 

19 80.0 90.0 9.9 Mean 

Max 

Mi n 

Rms 

G FAC 

PFAC 

90.0 90.0 9.8 Mean 

Max 

Mi n 

Rms 

G FAC 

PFAC 

Single Heliostat 
RUN # WIND TILT VELOCITY COMP: FX FY FZ MX MY MZ 

26 0 90.0 9.8 Mean 

Max 

Mi n 

Rms 

GFAC 

PFAC 

Mean 

Max 

Min 

Rms 

G FAC 

PFAC 

Mean 

Max 

Mi n 

Rms 

G FAC 

PFAC 

Mean 

Max 

Min, 

Rms 

GFAC 

PFAC 

22 65.0 90.0 10.1 Mean 

Max 
RUN # WIND TILT VELOCITY COMP: F X F Y F Z MX MY MZ 

Mi n 

Rms 

G FAC 

PFAC 

5 1 70.0 90.0 10.0 Mean 

Max 

Mi n 

Rms 

G FAC 

PFAC 

29 80.0 90.0 9.8 Mean 

Max 

Mi n 

Rms 

G FAC 

PFAC 

BACK 

-- -- 

LEFT I=[ 

FRONT 

Single Heliostat 
RUN # WIND TILT VELOCITY COMP: FX FY FZ MX MY MZ 

30 20.0 90.0 9.6 Mean 

Max 

Mi n 

Rms 

GFAC 

PFAC 

Mean 

Max 

Mi n 

Rms 

GFAC 

PFAC 

Mean 

Max 

Mi n 

Rms 

GFAC 

PFAC 

Mean 

Max 

Mi n 

Rms 

GFAC 

PFAC 

24 65.0 90.0 9.8 Mean 

Max 
RUN # WIND TILT VELOCITY COMP: FX F Y FZ MX MY MZ 

Mi n 

Rms 

GFAC 

PFAC 

3 2 80.0 90.0 9.6 Mean 

Max 

Mi n 

Rms 

GFAC 

PFAC 

LEFT 

FRONT / 

RIGHT 

Single Heliostat 
RUN # WIND TILT VELOCITY COMP: FX FY FZ MX MY MZ 

60.0 80.0 9.7 Mean 

Max 

Mi n 

Rms 

GFAC 

PFAC 

60.0 60.0 9.4 Mean 

Max 

Min 

Rms 

GFAC 

PFAC 

65.0 45.0 9.7 Mean 

Max 

Min 

Rms 

GFAC 

PFAC 

65.0 30.0 9.8 Mean 

Max 

Min 

Rms 

GFAC 

PFAC 

65.0 15.0 9.6 Mean 

Max 
-- - 

RUN # WIND TILT VELOCITY COMP: FX F Y FZ MX MY MZ 

Mi n 

Rms 

G FAC 

PFAC 

0.0 9.9 Mean 

Max 

Mi n 

Rms 

GFAC 

PFAC 

3 9 b5.0 15.0 9.9 hean 

Max 

Mi n 

Rms 

G FAC 

PFAC 

40 65.0 30.0 9.7 Mean 

Max 

Mi n 

Rms 

GFAC 

PFAC 

4 1 65.0 45.0 9.5 Mean 

Max 

Mi n 

Rms 
RUN # WIND TILT VELOCITY COMP: FX FY FZ MX MY MZ 

GFAC 

PFAC 

45 65.0 55.0 9.7 Mean 

Max 

Mi n 

Rms 

GFAC 

PFAC 

42 65.0 60.0 9.5 Mean 

Max 

Mi n 

Rms 

GFAC 

PFAC 

47 65.0 65.0 9.7 Mean 

Max 

Mi n 

Rms 

G FAC 

PFAC 

Mean 

Max 

Mi n 

Rms 

GFAC 

PFAC 
RUN # WIND TILT VELOCITY COMP: FX F Y F Z MX MY MZ 

43 65.0 80.0 10.0 Mean .823 - ,853 .265 .011 .043 .255 

Max 2.088 .lo4 -652 .I67 .I93 .708 

Mi n .087 -2.295 - .003 - .161 - .086 .021 

Rms .287 .362 .096 .037 .034 .087 

G FAC 2.536 2.689 2.461 15.159 4.523 2.782 

PFAC 4.413 3.984 4.024 4.162 4.421 5.236 
Data File: SCT2 

For Sing1 e Round Model 

In the file labelled "SCT" the coefficient denoted by "MX" and "MY" are the 

base moment coefficients. However, in the files labelled "SCT1" and "SCT2" 

the coefficient of "MX" and "MY" are the hinge moment coefficients about the 

y-axis at the motor drive level. 

Comment: MY is the hinge moment coefficient, C in data file: SCT2 MHY 

RUN # WIND TILT VELOCITY COMP: FX FY FZ MX MY MZ 

57 .O 90.0 9.9 Mean 

Max 

Min 

Rms 

G FAC 

PFAC 

58 15.0 90.0 9.8 Mean 

Max 

Mi n 

Rms 

G FAC 

PFAC 

59 30.0 90.0 9.9 Mean 

Max 

Mi n 

Rms 

GFAC 

PFAC 

60 45.0 90.0 9.8 Mean 

Max 

Mi n 

Rms 

G FAC 

PFAC 

61 55.0 90.0 10.0 Mean 

Max 
RUN # WIND TILT VELOCITY COMP: FX F Y FZ MX MY MZ 

Mi n 

Rms 

G FAC 

PFAC 

60.0 90.0 9.9 Mean 

Max 

Mi n 

Rms 

GFAC 

PFAC 

70.0 90.0 10.0 Mean 

Max 

Mi n 

Rms 

G FAC 

PFAC 

65.0 90.0 9.7 Mean 

Max 

Mi n 

Rms 

G FAC 

PFAC 

65 75.0 90.0 10.0 Mean 

Max 

Mi n 

Rms 
RUN # WIND TILT VELOCITY COMP: FX FY FZ MX MY MZ 

GFAC 

PFAC 

66 80.0 90.0 9.6 Mean 

Max 

Mi n 

Rms 

GFAC 

PFAC 

67 90.0 90.0 10.2 Mean 

Max 

Mi n 

C, 

Rms 

00 

V GFAC 

PFAC 

BACK 

FRONT 

LEFT RIGHT 

Single Heliostat 
RUN # WIND TILT VELOCITY COMP: FX F Y F Z MX MY MZ 

68 15.0 90.0 9.7 Mean 

Max 

Mi n 

Rms 

G FAC 

PFAC 

6 9 30.0 90.0 9.9 Mean 

Max 

Mi n 

Rms 

GFAC 

PFAC 

c.' 

CO 

CO 7 0 45.0 90.0 10.0 Mean 

Max 

Mi n 

Rms 

GFAC 

PFAC 

7 1 55.0 90.0 9.9 Mean 

Max 

Mi n 

Rms 

GFAC 

PFAC 

72 60.0 90.0 9.8 Mean 

Max 
RUN # WIND TILT VELOCITY COMP: FX FY FZ MX MY MZ 

Min 

Rms 

G FAC 

PFAC 

73 65.0 90.0 9.8 Mean 

Max 

Mi n 

Rms 

GFAC 

PFAC 

75 70.0 90.0 9.8 Mean 

+ Max 

w 

a Mi n 

Rrns 

GFAC 

PFAC 

76 80.0 90.0 9.7 Mean 

Max 

Mi n 

Rms 

G FAC 

PFAC 

77 90.0 90.0 9.9 Mean 

Max 

Mi n 

Rms 
RUN # WIND TILT VELOCITY COMP: FX FY F Z MX MY MZ 

G FAC 2.388 16.100 29.071 26.156 11.428 10.610 

PFAC 3.900 4.109 4.089 3.858 4.679 3.966 

1-1 RIGHT 

Single Heliostat 
RUN # WIND TILT VELOCITY COMP: FX FY FZ MX MY MZ 

.O 90.0 9.7 Mean 

Max 

Mi n 

Rms 

GFAC 

PFAC 

20.0 90.0 9.9 Mean 

Max 

Min 

Rrns 

G FAC 

PFAC 

40.0 90.0 9.9 Mean 

Max 

Min 

Rms 

GFAC 

PFAC 

55.0 90.0 9.9 Mean 

Max 

Mi n, 

Rms 

GFAC 

PFAC 

60.0 90.0 9.8 Mean 

Max 
RUN # WIND TILT VELOCITY COMP: FX F Y FZ MX MY MZ 

Rms 

G FAC 

PFAC 

83 65.0 90.0 9.8 Mean 

Max 

Mi n 

Rms 

GFAC 

PFAC 

84 70.0 90.0 10.1 Mean 

Max 

Mi n 

Rms 

G FAC 

PFAC 

8 5 75.0 90.0 9.9 Mean 

Max 

Mi n 

Rms 

GFAC 

PFAC 

86 80.0 90.0 9.9 Mean 

Max 

Mi n 

Rms 
RUN # WIND TILT VELOCITY COMP: FX FY FZ MX MY MZ 

G FAC 2,951 3.621 5.970 22.211 19.867 3.203 

PFAC 3.937 3.619 3.566 4.287 3,662 3.738 

88 85.0 90.0 9.6 Mean .I56 .621 - .046 - .004 . 000 - .I48 

Max ,470 2.825 .I81 ,167 .040 ,164 

Mi n - ,018 -.918 - .322 -. 240 - .027 - .590 

Rms ,067 ,495 .070 ,048 .008 ,099 

G FAC 3.020 4.552 7.001 54.597 175.137 3.982 

PFAC 4,704 4.451 3.932 4.877 3.304 4.467 

Mean 

Max 

Min 

Rms 

GFAC 

PFAC 

LEFT (m 

Single Hel iostat 
RUN # WIND TILT VELOCITY COMP: FX F Y F Z MX MY MZ 

89 20.0 90.0 9.8 Mean 

Max 

Mi n 

Rms 

G FAC 

P FAC 

9 0 40.0 90.0 10.1 Mean 

Max 

Mi n 

Rms 

G FAC 

PFAC 

w 

ko 

P 9 1 55.0 90.0 9.9 Mean 

Max 

Mi n 

Rms 

G FAC 

PFAC 

92 60.0 90.0 9.6 Mean 

Max 

Mi n 

Rms 

G FAC 

PFAC 

93 65.0 90.0 10.0 Mean 

Max 
RUN # WIND TILT VELOCITY COMP: FX FY FZ MX MY MZ 

Mi n 

Rms 

GFAC 

PFAC 

94 70.0 90.0 9.8 . Mean 

Max 

Mi n 

Rms 

GFAC 

PFAC 

95 75.0 90.0 9.7 Mean 

Max 

Mi n 

Rms 

G FAC 

PFAC 

96 80.0 90.0 9.7 Mean 

Max 

Mi n 

Rrns 

G FAC 

PFAC 

97 85.0 90.0 9.5 Mean 

Max 

Min 

Rms 
RUN # WIND TILT VELOCITY COMP: 

G FAC 

PFAC 

LEFT R l GHT 

Single Heiiostat 
. 

RUN # WIND TILT VELOCITY COMP: FX FY FZ MX MY MZ 

98 65.0 75.0 9.6 Mean 

Max 

Min 

Rms 

GFAC 

PFAC 

9.8 Mean 

Max 

Mi n 

Rms 

G FAC 

PFAC 

9.8 Mean 

Max 

Mi n 

Rms 

G FAC 

PFAC 

9.7 Mean 

Max 

Mi n 

Rms 

G FAC 

PFAC 

102 65.0 15.0 9.6 Mean 

Max 
RUN # WIND TILT VELOCITY COMP: F X F Y F Z MX MY MZ 

Mi n 

Rms 

G FAC 

PFAC 

103 65.0 .O 9.6 Mean 

Max 

Mi n 

Rms 

G FAC 

PFAC 

104 65.0 15.0 9.6 Mean 

Max 

Mi n 

Rms 

GFAC 

PFAC 

105 65.0 30.0 9.4 Mean 

Max 

Mi n 

Rms 

GFAC 

PFAC 

106 65.0 45.0 9.7 Mean 

Max 

Mi n 

Rms 
RUN # WIND TILT VELOCITY COMP: FX FY FZ MX MY MZ 

GFAC 

PFAC 

107 65.0 55.0 9.8 Mean 

Max 

Mi n 

Rms 

GFAC 

PFAC 

108 65.0 60.0 9.9 Mean 

Max 

Mi n 

Rms 

G FAC 

PFAC 

109 65.0 65.0 9.5 Mean 

Max 

Mi n 

Rms 

G FAC 

PFAC 

110 65.0 70.0 9 . 6 Mean .680 -1.143 .605 .024 . 076 .249 

Max 1.725 -.017 1.495 .260 .321 .712 

Min -.014 -2.947 .018 -. 132 - .066 .010 

Rms .268 .478 .220 .045 .045 .090 

G FAC 2.538 2.579 2.471 11.068 4.240 2.860 

PFAC 3.896 3.776 4.042 5.311 5.461 5.168 
RUN # WIND TILT VELOCITY COMP: FX F Y FZ MX MY MZ 

11 1 65.0 75.0 10.0 Mean 

Max 

Mi n 

Rms 

GFAC 

PFAC 

65.0 80.0 9.6 Mean 

Max 

Mi n 

Rms 

G FAC 

P FAC 

65.0 85.0 9.8 Mean 

Max 

Mi n 

Rms 

GFAC 

P FAC 

65.0 90.0 9.5 Mean 

Max 

Mi n 

Rms 

G FAC 

PFAC 
Data File: SCT2 

For Field Study 

In the file labelled "SCT" the coefficient denoted by "MX" and "MY" are the 

base moment coefficients. However, in the files labelled "SCTZ" and "SCT2" 

the coefficient of "MX" and "MY" are the hinge moment coefficients about the 

y-axi s at the motor drive 1 eve1 . 

Comment: MY is the hinge moment coefficient, CMHy in data file: SCT2 
RUN # WIND TILT VELOCITY COMP: FX F Y F Z MX MY MZ 

129 60.0 60.0 10.3 Mean 

Max 

Mi n 

Rms 

G FAC 

PFAC 

130 60.0 60.0 9.9 Mean 

Max 

Mi n 

Rms 

G FAC 

PFAC 

60.0 9.8 Mean 

Max 

Mi n 

Rms 

G FAC 

PFAC 

132 60.0 60.0 9.6 Mean 

Max 

Mi n 

Rms 

G FAC 

PFAC 

133 60.0 60.0 9.7 Mean 

Max 
RUN # WIND TILT VELOCITY COMP: FX FY FZ MX MY MZ 

Min .088 - .830 .136 - .085 - .003 .051 

Rms .lo2 .I11 .074 ,027 .033 .038 

GFAC 2.131 2.380 1.967 51.076 2.525 1.924 

PFAC 4.166 4.340 4.354 4.918 4.537 4.101 

134 60.0 60.0 9.7 Mean 

Max 

Mi n 

Rms 

G FAC 

PFAC 

135 60.0 60.0 9.7 Mean 

Max 

Min 

Rms 

G FAC 

PFAC 

136 60.0 60.0 9.8 Mean 

Max 

Mi n 

Rrns 

G FAC 

PFAC 

137 60.0 60.0 9.5 Mean 

Max 

Mi n 

Rms 
RUN # WIND TILT VELOCITY COMP: F X F Y FZ MX MY MZ 

G FAC 2.417 3.705 2.519 111.601 3.172 2.129 

P FAC 4.580 4.485 4.333 3.628 4.974 4.275 

138 60.0 60.0 9.8 Mean .I96 -.I93 .184 .013 .045 .079 

Max .692 .129 .534 .I46 .207 .232 

Mi n - .044 - .749 - .045 - .060 - .022 - ,009 

Rms .088 .I16 .078 .024 .026 .031 

G FAC 3.529 3.881 2.906 11.529 4.651 2.919 

PFAC 5.612 4.802 4.514 5.535 6.189 4.907 

139 60.0 60.0 9.7 Mean .225 - .207 .I64 .019 .046 .076 

Max .674 .083 .441 .I59 .172 .216 

Mi n - .005 - .724 - .043 - .070 - .024 - .007 

~3 Rms .092 .118 .079 .026 .028 .032 

0 P G FAC 3.001 3.492 2.694 8.549 3.757 2.832 

PFAC 4.883 4.387 3.533 5.476 4.475 4.357 

140 60.0 60.0 9.7 Mean ,252 -. 134 .123 - .001 .052 .lo3 

Max .525 .lo1 .329 ,126 .I69 .223 

Mi n .040 - ,493 - .014 - .071 - .025 .022 

Rms .072 .084 .049 .023 .024 .027 

GFAC 2.085 3.691 2.686 110.462 3.264 2.166 

PFAC 3.786 4.267 4.184 3.036 4.854 4.446 

14 1 60.0 60.0 9.7 Mean .515 - .544 .442 ,004 .lo0 .I94 

Max .878 - .190 .791 .084 .207 .295 

Mi n .250 -1.046 .217 - .068 .022 .096 

Rms .088 .I10 .072 .020 .022 .028 

GFAC 1.705 1.922 1.789 19.256 2.074 1.520 

PFAC 4.128 4.553 4.854 4.065 4.875 3.673 
RUN # WIND TILT VELOCITY COMP: FX FY FZ MX MY MZ 

142 60.0 60.0 9.8 Mean 

Max 

Min 

Rms 

GFAC 

PFAC 

Mean 

Max 

Mi n 

Rms 

GFAC 

PFAC 

Mean 

Max 

Mi n 

Rms 

GFAC 

PFAC 

Mean 

Max 

Mi n 

Rms 

GFAC 

PFAC 

146 60.0 60.0 9.8 Mean 

Max 

Mi n 

Rms 
RUN # WIND TILT VELOCITY COMP: FX FY F Z MX MY MZ 

G FAC 

PFAC 

147 60.0 60.0 9.6 Mean 

Max 

Mi n 

Rms 

G FAC 

PFAC 

148 60.0 60.0 9.5 Mean 

Max 

Mi n 

r~ Rms 

0 

QI G FAC 

PFAC 

149 60.0 60.0 9.5 Mean 

Max 

Mi n 

Rms 

GFAC 

PFAC 

137 60.0 60.0 9.7 Mean 

Max 

Mi n 

Rms 

G FAC 

PFAC 
RUN # WIND TILT VELOCITY COMP: FX FY FZ MX MY MZ 

138 60.0 90.0 9.7 Mean 

Max 

Mi n 

Rms 

GFAC 

PFAC 

139 60.0 90.0 9.5 Mean 

Max 

Mi n 

Rms 

G FAC 

PFAC 

IV 

0 

V 140 60.0 90.0 9.4 Mean 

Max 

Mi n 

Rms 

GFAC 

PFAC 

Mean 

Max 

Min 

Rms 

GFAC 

PFAC 

142 60.0 90.0 9.7 Mean 

Max 
RUN # WIND TILT VELOCITY COMP: FX F Y F Z MX MY MZ 

Mi n 

Rms 

G FAC 

PFAC 

143 60.0 90.0 9.4 Mean 

Max 

Mi n 

Rms 

G FAC 

PFAC 

144 60.0 90.0 9.2 Mean 

lV Max 0 

a3 Mi n 

Rms 

G FAC 

PFAC 

145 60.0 90.0 9.6 Mean 

Max 

Mi n 

Rms 

G FAC 

PFAC 

146 65.0 90.0 9.6 Mean 

Max 

Mi n 

Rms 
- - 

RUN # WIND TILT VELOCITY COMP: FX FY FZ MX MY MZ 

GFAC 

PFAC 

90.0 9.6 Mean 

Max 

Mi n 

Rms 

GFAC 

PFAC 

90.0 9.7 Mean 

Max 

Mi n 

Rms 

GFAC 

PFAC 

90.0 9.7 Mean 

Max 

Mi n 

Rms 

GFAC 

PFAC 

150 65.0 90.0 9.8 Mean .335 - .417 .065 .013 .005 .lo3 

Max .670 - .013 .I43 ,133 .070 .268 

Mi n .091 -1.029 .003 - .069 - .053 - .022 

Rms .076 .I47 .020 .026 .017 .045 

GFAC 1.999 2.465 2.184 9.942 13.853 2.606 

PFAC 4.421 4.155 3.947 4.601 3.750 3.654 
RUN # WIND TILT VELOCITY COMP: FX F Y FZ MX MY MZ 

151 65.0 90.0 9.7 Mean 

Max 

Mi n 

Rms 

G FAC 

P FAC 

65.0 90.0 9.6 Mean 

Max 

Mi n 

Rms 

G FAC 

PFAC 

65.0 90.0 9.6 Mean 

Max 

Mi n 

Rms 

G FAC 

PFAC 

65.0 90.0 9.6 Mean 

Max 

Mi n 

Rms 

GFAC 

PFAC 

155 65.0 90.0 9.6 Mean 

Max 
RUN # WIND TILT VELOCITY COMP: FX FY FZ MX MY MZ 

Mi n 

Rms 

G FAC 

PFAC 

65.0 90.0 9.7 Mean 

Max 

Mi n 

Rms 

GFAC 

PFAC 

65.0 90.0 9.7 Mean 

Max 

Min 

Rms 

GFAC 

PFAC 

58 60.0 60.0 9.7 Mean 

Max 

Mi n 

Rms 

G FAC 

PFAC 

159 60.0 60.0 9.7 Mean 

Max 

Mi n 

Rms 
RUN # WIND TILT VELOCITY COMP: FX FY F Z MX MY MZ 

G FAC 

P FAC 

160 60.0 60.0 9.6 Mean 

Max 

Mi n 

Rms 

GFAC 

PFAC 

60.0 60.0 9.7 Mean 

Max 

Mi n 

Rms 

G FAC 

PFAC 

60.0 90.0 9.7 Mean 

Max 

Mi n 

Rms 

GFAC 

PFAC 

60.0 90.0 9.7 Mean 

Max 

Mi n 

Rms 

G FAC 

PFAC 
. - - - -- -- - -- - 

RUN # WIND TILT VELOCITY COMP: FX FY FZ MX MY MZ 

164 60.0 90.0 9.5 Mean 

Max 

Mi n 

Rms 

GFAC 

PFAC 

Mean 

Max 

Min 

Rrns 

GFAC 

PFAC 

Mean 

Max 

Min 

Rrns 

G FAC 

PFAC 

Mean 

Max 

Mi n 

Rms 

GFAC 

PFAC 

168 60.0 90.0 9.7 Mean 

Max 
RUN # WIND TILT VELOCITY COMP: FX F Y F Z MX MY MZ 

Mi n .I17 -1.202 - .015 - .068 - .050 .022 

Rms .I30 .I50 .022 .028 ,022 .039 

G FAC 2.455 3.112 2.558 6.497 8.037 2.309 

PFAC 4.946 5.445 3.994 4.460 5.682 4.015 

60.0 90.0 9.6 Mean .482 - .433 .051 .024 .019 .I37 

Max 1.153 ,158 .I36 .I42 .123 .333 

Mi n .070 -1.273 - .020 - .092 - -085 .007 

Rms .I44 ,169 .023 .029 .023 .045 

G FAC 2.394 2.941 2.666 5.845 6.504 2.426 

PFAC 4.666 4.980 3.686 4.022 4.563 4.362 

170 60.0 90.0 9.7 Mean 

Max 

Mi n 

Rms 

G FAC 

PFAC 

17 1 60.0 90.0 9.6 Mean 

Max 

Mi n 

Rms 

G FAC 

PFAC 

172 60.0 90.0 9.8 Mean 

Max 

Mi n 

Rrns 
RUN # WIND TILT VELOCITY COMP: FX FY FZ MX MY MZ 

GFAC 

PFAC 

65.0 90.0 9.8 Mean 

Max 

Mi n 

Rms 

GFAC 

PFAC 

65 + 0 90.0 9.6 Mean 

Max 

Mi n 

Rms 

G FAC 

PFAC 

65.0 90.0 9.6 Mean 

Max 

Mi n 

Rms 

GFAC 

PFAC 

65.0 90.0 9.6 Mean 

Max 

Mi n 

Rms 

GFAC 

PFAC 
- -- - -- - - 

RUN # WIND TILT VELOCITY COMP: FX F Y F Z MX MY MZ 

177 60.0 90.0 9.7 Mean 

Max 

Mi n 

Rms 

G FAC 

PFAC 

178 60.0 90.0 9.6 Mean 

Max 

Mi n 

Rms 

G FAC 

PFAC 

N 

c. 

0-l 179 60.0 90.0 9.7 Mean 

Max 

Mi n 

Rms 

G FAC 

PFAC 

180 60.0 90.0 9.8 Mean 

Max 

Mi n 

Rms 

G FAC 

PFAC 

181 60.0 90.0 9.7 Mean 

Max 
RUN # WIND TILT VELOCITY COMP: FX FY FZ MX MY MZ 

Min 

Rms 

GFAC 

PFAC 

182 60.0 90.0 9.7 Mean 

Max 

Mi n 

Rms 

GFAC 

PFAC 

183 60.0 90.0 9: 6 Mean 

Max 

Min 

Rms 

G FAC 

PFAC 

184 60.0 90.0 9.6 Mean 

Max 

Mi n 

Rms 

GFAC 

PFAC 

185 65.0 90.0 9.7 Mean 

Max 

Min 

Rms 
RUN # WIND TILT VELOCITY COMP: FX F Y FZ MX MY MZ 

G FAC 

PFAC 

186 65.0 90.0 9.6 Mean 

Max 

Mi n 

Rms 

G FAC 

PFAC 

187 65.0 90.0 9.8 Mean 

Max 

Mi n 

Rms 

G FAC 

PFAC 
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U.S. GOVERNMENT PRINTING 0FLICE:lg 8 7 -77 3 -0 9 8/ 6 0 0 4 2 
1 Document Control I 1. SERl Report No 1 2. NTlS Accession No. 1 3. Recipient's Accession No. 1 

7.Author(s) J. A. Peterka, L. Tan. B. Bienkiewicz. 

Page I ~~~1/~~~-253-32121 

4. Title and Subtitle 

Mean and Peak Wind Load Reduction on Heliostats 

J. E. Cermak 

9. Performing Organ~zatlon Name and Address 

Fluid Mechanics & Wind Eng. Program 

Col orado State University 

Fort Collins, CO 80523 

5. Publication Date 

September 1987 

6. 

12 Sponsoring Organlzat~on Name and Address 

Solar Energy Research Institute 

A Division of Midwest Research Institute 

1617 Cole Boulevard 

Golden, CO 80401-3393 

8 Performing Organlzat~on Rept No 

11. Contract (C) or Grant (G) No 

13. Type of Report & Per~od Covered 

Technical Report - 

14. 

5. Supplementary Notes 1 

Technical Monitor: A. Lewandowski 

16. Abstract (Llmlt: 200 words) 

This report presents the results of wind-tunnel tests supported through the Solar 

Energy Research Institute (SERI) by the Office of SolarThermal Technology of the 

U.S. Department of Energy as part of the SERI research effort on innovative concentrators. As gravity 1 oads on drive rnechani sms are reduced through stretchedmembrane techno1 ogy, the wind-load contribution of the required drive capacity 

increases in percentage. Reduction of wind loads can provide economy in support 

structure and heliostat drive. Wind-tunnel tests have been directed at finding 

methods to reduce wind loads on heliostats. The tests investigated both mean 

and peak forces, and moments. A significant increase in ability to predict 

he1 iostat wind loads and their reduction within a he1 iostat fie1 d was achieved. 

In addition, a preliminary review of wind loads on parabolic dish collectors was 

conducted, resul ti ng in a recommended research program for these type col 1 ectors. 

17. Document Analys~s I a Descriptors Dynamic Loads; Heliostats; Solar Concentrators, Stresses; Wind; 

Wind Loads, Wind Load Reduction; Dishes 

b. Identtf~ers/Open-Ended Terms 

1 18. Availability Statement 

National Technical Information Service 

U.S. Department of Commerce 

5285 Port Royal Road 

Springfield, Virginia 22161 

19. No. of Pages 

240 

1 

20. Prlce 

A1 1 

Form No. 0069 (6-30-87)