NASA Technical Memorandum 107397

AIAA-97-0049

//v'- 3_

Validation of NASA Thermal Ice Protection

Computer Codes

Part 1-Program Overview

Dean Miller, Thomas Bond, and David Sheldon

Lewis Research Center

Cleveland, Ohio

William Wright and Tammy Langhals

NYMA, Inc.

Brook Park, Ohio

Kamel A1-Khalil

Cox & Company, Inc.

New York, New York

Howard Broughton

Cortez III Service Corporation

Cleveland, Ohio

Prepared for the

35th Aerospace Sciences Meeting & Exhibit

sponsored by the American Institute of Aeronautics and Astronautics

Reno, Nevada, January 6-10, 1997

National Aeronautics and

Space Administration

VALIDATION OF NASA THERMAL ICE PROTECTION COMPUTER CODES

PART 1 - PROGRAM OVERVIEW

Dean Miller

Thomas Bond

David Sheldon

NASA- Lewis Research Center

Wiltiam Wright

Tammy Langhals

NYMA, Inc.

Kamel Al-Khalil

Cox & Company, Inc.

Howard Broughton

Cortez HI Service Corporation

ABSTRACT NOMENCLATURE

The Icing Technology Branch at NASA-Lewis has

been involved in an effort to vafidate two thermal ice

protection codes developed at the NASA-Lewis

Research Center. LEWICE/Thermal (electrothermal

de-icing & anti-icing), and ANTICE (hot-gas &

electrothermal anti-icing). The Thermal

Validation effort was designated as a priority during a

1994 "peer review" of the NASA-Lewis Icing program,

and was implemented as a cooperative effort with

indusUy.

During April 1996, the first of a series of experimental

validation tests was conducted in the NASA-Lewis

Icing Research Tunnel 0RT). The purpose of the

April 96 test was to acquire experimental data to

validate the dectrothermai predictive capabilities of

both LEWICE/Thermal, and ANTICE. A heavily

instrumented test article was designed and fabricated to

simulate dectrothermal de-icing and anti-icing modes

of opcratio_ Thermal measurements were then

obtained over a range of test conditions, for

comparison with analytical predictions.

This paper presents an overview of the test, including a

detailed description of (1) test article design, (2) test

matrix development, (3) test procedures, and (4)

validation process. Selected experimental results are

presented for de-icing and anti-icing modes of

operation. Finally, the status of the validation effort at

this point is summarized.

AOA

Beta

IRT

LWC

MVD

ON/OFF

Q

POI

RTD

S

T.,_

T_t

T_t

TTMS

V

Angle-Of-Attack (degrees)

Collection Efficiency

Icing Research Tunnel

Liquid Water Content (g/m 3)

Median Volumetric Diameter (tan)

Heater On / OffTime (seconds)

Heater Flux (Watts/in 2)

Point Of Interest

Resistance Temperature Device

Wrap Distance (inches)

Evaporative Anti-Icing Temp. (*F)

Running Wet Anti-Icing Temp. (OF)

Total Temperature (oF)

Test Thermal Management System

Airspeed (mph)

INTRODUCTION

In 1994 the Icing Technology Branch at NASA-Lewis

Research Center conducted a "l_eer-review" process to

prioritize it's programs, based on technological needs

identified by industry partners. The need for validated

Thermal Ice Protec_on computer codes was identified

as a priority, during this "peer-review" process. As a

result, NASA established an experimental program to

validate two NASA developed Thermal Ice Protection

codes: LEWICFJThermal (transient electrothermal deicing & anti-icing), and ANTICE (steady-state hot-gas

& electrothermal anti-icing).1'2

Two experimental tests comprise this validation

activity. The first test utilized an airfoil with an
eleetm-tlwrmal ice protection system and will be used

to validate the eleetro4hermal de-icing and aafiicing predictive capability of LEWICF3Thenn_, and

the electro-thermal anticing predictive capability of

ANTICE. This test was conductod in April 96, and is

the subject of this paper. The second experimental test

in the Thermal Code Validation effort will utilize an

airfoil with a hot-gas ice protection system, and will be

used to validate the hot-gas anti-icing predictive

capability of ANTICE. This second test is currently

planned for a 2-3 week time period in CY 97-98.

The Thermal Code Validation program was initially

conceived as a cooperative effort to provide a close

coupling between NASA-Lewis and industry during

the validation process. It was felt this cooperative

relationship was essential to ensure that the "validated"

codes would meet the needs of the ice protection

indumy. For this first Thermal Code Validation test

there were two categories of cooperative participation

by indmUy partners. The first category involved

providing technical advice to guide the model design,

fabrication, and test plan developmem_ The second

ca_goryinvolved providing the actual test hardware &

support, in addition to the technical participation

described above. The companies involved in the first

Thermal Code Validation test are listed below, along

with their participation category:

• B.F. Goodrich Aerospace ... category 1

• Boeing Commercial Airplane ... category 1

• Cox & Company... category 2

• GE Aircraft Engines ... category 1

• Rohr Industries ... category I

This paper will provide an overview of the first

Thermal Code Validation Test, conducted in the

NASA-Lewis Icing Research Tunnel (IRT) in April

1996. The scope of this paper will be limited to a

description of the test article design and

instrumentation, test matrix development, test

procedures employed, and summary of the validation

process. Though some typical results will be

presented, detailed comparisons between analytical

predictions and experimental results are contained in

thefollowingtwopapers:s'4

"Validation of NASA Thermal Ice Protection

Computer Codes: Part 2 The Validation of

LEWICF_.rrhermal"

"Validation of NASA Thermal Ice Protection

Computer Codes: Part 3 - The Validation of ANTICE."

TEST FACILITY DESCRIFrlON

Icing Research Tunnel

The experimental testing to validate NASA's Thermal

Ice Protection codes was conducted in the NASA Lewis

Icing Research Tunnel (IRT). s The NASA IRT is a

closed-loop rcfrigeratod wind tunnel. The test section

is 6 fl high and 9 fl wide, and contains a turntable

assembly which allows for model angle-of-attack

changes. A 5000 hp fan provides airspeods up to 400

mph (empty test section). The refrigeration heat

exchanger can control the air temperature from +40 °F

to-40 W. The water spray system has been cah_orated

for simulating icing clouds with droplet MVD of 14 to

40pro, and Liquid Water Content (LWC) of 0.2 - 3.4

g/m s. Figure I shows a schematic view of the IRT.

TEST ARTICLE DESCRIPTION

Model Description

The test article was a NACA-0012 airfoil which had a

72 inch span, and a 36 inch chord. The model was

fabricated in two pieces: a leading edge section (10

inch chord),and a wooden aflcrbody (26 inch chord).

Figure 2 is a picture of the test article installed in the

IRT.

The composite leading edge was designed and

fabricated by Cox & Company specifically for this test.

This leading edge section had seven independently

controllable heater zones as shown in Figure 3. Each

zone had an upper and lower heating element

Both heating elements were separately controlled to the

same operating setpoint. This operationally emulated a

sing_ spanwm heater zone, but providedrodendancy

in case a heater element shouldfail (which none did).

The amount of thermal energy supplied to each lmtcr

zone could be independently regulated using

temperature, or heat flux as the feedback contxol

pm'anmer.

The chordwise extent of the heater zones was

establishod during design using Lcwicc's droplet

impingement routine for a nominal droplet MVD of

20pro, at 100 & 200 mph airspeeds, and for a range of

Angle-Of-Attack (AOA). Figure 4 is a plot of the

collection efficiency (Beta) versus wrap distance (S)

from the leading-odge for 0°, 2 °, and 4 ° AOA. The

impingement limits can be seen on this plot for up to

4° AOA, which was the highest AOA tested with a

20tim droplet size. The collectivewidthoftheheated

zones (3.875") was chosen to extend chordwise slightly

beyond the area ofdirectimpingement. One minute

2
icingsprayswererunintheIRTatT_t=0° F and the

above conditions to confirm that the heated zones

extended far enough aft on the leading-edge.

Experimental results confirmed that droplet

impingement was indeed within the thermally

protected area of the leading- edge.

As one might expect, zone A Cparting-strip') and

zones B & C would be subjected to greater water

loading and larger heat transfer coefficients than heater

zones farther aR on the airfoil surface (D, E, F, G).

Therefore, the maximmn design heat flux for heater

zones A (30 W/in2), B (30 W/in2), & C (30 W/in2) was

greater than for zones D (27 W/in2), E (27 W/in2), F

(16 W/in2), & G (16 W/in2). These design values

represented the maximum heat flux that could be

supplied to a particular zone. The actual heat flux

applied to a particular zone varied depending on the

test conditions, but in general was less than the

maximum value.

Guard heaters were also employed to minimize

spanwise heat flow within the test article. The guard

heaters were physically located above and below the

test area, which had a spanwise extent of

approximately +/- 18 inches about the model

centerline. The guard heaters were set to a nominal

operating tempemaae based on the observed surface

temperatures within the test are,&

A cross-se_onal view of the leadin__g-edgecomposite

gructme is shown in Figure 5, along with thermal

properties. The stainless steel abrasion shield was the

outermost layer and therefore exposed to the icing

environment. Note that the heater element is

represented as a thin layer having equivalent crosssectional surface area as that of the electrical

conductors in the healing elemcnL This representation

is consistent with the modeling of the electrical heating

elements in LEWICEgghermal and ANTICE. A

relatively thick layer of insulation formed the

innermost layer of the composite structure, and helped

to minimiTe heat flew back into the interior of the test

article.

Instrumentation Design

The primm7 method for validating the thermal ice

protection codes was planned to be via comparison of

measured and predicted temperature profiles within the

leading-edge structnre. This validation approach was

the dominant factor in designing the instrumentation

layouL

A "benchtest" of the planned instrumentation design

was conducted prior to fabrication of the composite

leading-edge. A 6 inch by 6 inch representation of the

composite leading-edge, including heater and

instrumentation, was fabricated and tested. The

"benchtest" was intended to verify the accuracy of the

temperature measurement approach, as well as

identifying any potential fabrication issues early in the

design process. The "benchtest" results verified the

instrumentation design approach, but indicated a

potential problem associated with the heat flux gage

leadwires which will be discussed later in this section.

Figure 6a shows the instrumentation layout with the

leading-edge unwrapped. Note that there were 14

sensor locations (2 locations per heater zone)

positioned within 4.5 inches of the test article

centerline. This was done to ensure that the sensor

locations would be unaffected by any potential end

effects occurring at the edges of the Test Area (+/- 18

inches above and below the centerline). Also, each

sensor location was centered within it's respective

heater zone (in the direction parallel to the chord line).

An infrared camera was also used to obtain a

temperature map of a portion of the test area as shown

in Figure 6& This long-wave infrared camera was

cooled with a Stirring cycle engine, and had a scanning

system with a 8-12 micron spectral response.

Since the abrasion shield of the test article was

constructed of polished stainless steel, it emitted only

2% and reflected close to 98% of the ambient radiant

energy. To eliminate the reflections, the region of

interest was spray painted flat black. This raised the

emissivity, and reduced the reflections. The camera

system was calibrated using electrical tape with a

known emissivity which showed that the flat black

paint increased the emissivity of the surface to 97%.

The IR camera was fitted with a 40 degree, medium

telephoto lens providing a field of view which captured

the upper portion of the heater zones shown in Figure

6a. Six points of interest (POI) were selected in the

upper portions of zones B, D, F. The temperature at

each POI was averaged to provide a smooth

temperature plot as a function of time.

During a run, the IR camera would capture one image

eveay second for the duration of the run and write those

images to the hard drive of the system controller.

Concurrent with the image capture, the six POI

temperatures were plotted in real time on the monitor,

and the last thousand POI temperature data points

saved to the hard drive for later analysis.
SincethiswasthefirsttimeNASAusedthiscamerain

anicingtest,it wasdecidednot to utilize it as a

primary temperature measurement for validation

purposes. It did, however, provide an independent

check on the outer temperature measurement described

above, and provided valuable qualitative information

about the uniformity of the surface temperature within

the test are&

A crees-sectional view at a typical sensor location is

also shown in Figure 6b. There were 3 temperatnre

sensors and a heat flux gage within each sensor

location. Note that the temperatnre sensors were

located so as to provide a transverse temperature

profile (i.e.-axis normal to the surface) for co_n

with code predictions. Some details about each sensor

arc provided below:

A type T thermocouple was welded to the

underside of the stainless steel abrasion shield.

Since the abrasion shield was only .008 inches

thick, this temperature measurement should be

very near the actual surface temperanne

An RTD was located just under the heater dement

to obtain a temperatme measurement near the

heater. Though the temperature measured at this

location is somewhat less than the actual heater

temperature, it does provide some indication as to

the magnitude of the heater temperature.

A type T thermocouple was welded to a small

stainless steel tab which was then attached to the

underside of the insulation layer with a thermally

conductive cement.

The heat flux gage was a thermoptle type enclesed

in a polyimide film with relatively large leadwires

(.010 inch diameter). Originany, it had been

planned to locate the heat flux gage above the

heater clement, but just below the abrasion shield.

However, there was a potential for air voids to

form around the heat flux gage leadwires during

the fabrication process. Since these air voids could

lead to overheating and failure of the heating

element beneath the voids, it was decided to move

the heat flux gage bclow the heater as shown in

Figure 6b. In this position, the absolute magnitude

of the heat flux gage signal was greatly reduced

(over a factor of 20), since almost all of the

thermal energy flows from the heater outward

through the abrasion shield.

Measurement Uncertainty:

The 3 test article temperature measurements described

above were intended to serve as a reference against

which the "goodness" of the analytical predictions

would ultimately be judged. Therefore, it was

important to have an estimate of the mxmminty

associated with each temperature measurmncnt, lnan

attempt to _dmate this encertainty, three potential

uncertainty fairs were aonsidemd:

1. Positional uncertainty (i.e.- how well is the

sensor's actual position really known?)

2. Measurement uncertai_ intruduc_ by the data

acquisition process

3. Uncertainty due to the sensor's inherent accuracy

Temperature errors due to positional uncertainty were

only estimated for the Wdnsverse direction within the

leading-edge smtcture for each ofthe 3 sensors. While

itis recognized that this type of uncertainty has a three

dimensional aspect, temperature error due to positional

uncertainty in the chordwise or spanwise directions

was assmned to be negligl_ole when compared to

temperature errors due to positional uncertainty in the

uansverse direction. It was pos_'ble to estimate a

uncertainty based on the following: (1)

knowledge of the material _ in the immediate

vicinity of the sensor, (2) an assumed nominal heat

flux, and (3) an estimate of how much the Wansverse

position could be in error. Considering the foregoing,

temperature uncertainty estimates were calculated for

the abrasion shield thermocouple, RTD, and insulation

thermocouple at 3 nominal heater fluxes. These values

are listed in Table I for nominal applied heater fluxes

of 5 to 15 watts/in 2.

Measurement uncertainty due to the dam acquisition

process was estimated to be a fixed percentage of the

data system input stage full-scale range. This

uncertainty was estimated to be 0.5% for a

thermocouple input (+/-5mV Full-Scale range), and

1.0% for the RTD input (+/- IV Full-Scale range).

This translates to +/- 1.0°F for the thermocouples, and

+/- 1.6°F for the RTD.

Uncertainty due to inherent temperature sensor

accuracy was determined based on oil bath cah_orations

of a random sample of Type T thermocouples and

RTDs similar to those used in the test article. The

thcrmocouples had an uncertainty of +/- 0.1°F, while

the RTD uncertainty was determined to be +/- 1.9°F.

4
An overallvalueof temperatureuncertaintywas

determinedforeach of the three temperature sensors by

calculating the root-sum-square of the previously

determined uncertainties, as shown in Table I.

TEST MATRIX

Development of the test matrix involved the selection

of two different types of parameters: icing parameters

(T_ , LWC, MVD, etc), and electro-thermal ice

protection system parameters (heater power level, and

heater zone ON/OFF time). The combination of both

sets of parameters resulted in an extremely large

number of possible test parameter combinations for

potential inclusion in the test matrix. Consequently, it

was decided to restrict testing to a few different icing

conditions (i.e.- limit the number of icing parameter

combinations), but thoroughly evaluate the ice

protection system parameters at each of these selected

icing conditions.

Icing Condition Parameter Selection

Two icing test conditions were selected based on the

criteria that they were: (1) generally representative of a

thermal ice protection system design point, (2)

reproducible by the IRT spray system, and (3) within

the FAR-25 icing envelope.

• T_ = 20°F, V=100mph, LWC=.78 g/m3,

MVD=201ml, AOA=0 °

• T_ = O°F, V=100mph, LWC=.78 g/m3,

MVDf20ttm, AOA=0 °

These two conditions were given the label of "anchor

point". At each of these two icing conditions, ice

protection system parameters were varied. This

enabled the ice protection codes' predictive capabilities

to be thoroughly evaluated with respect to a reference

icing condition (i.e.- an "anchor point"). Additional

icing condilions were also selected to validate both

codes' predictive capability at other points within the

FAR-25 envelope. However, ice protection system

parameters were not varied at these conditions. A list

of icing test conditions is contained in Table H.

Ice Protection System Parameter Selection

The primary parameters to be considered were the heat

flux (Q) applied to each heater zone, and the time

sequencing of Q to each zone (ON/OFF time).

Typically, higher Q was applied to the forward heater

zones; therefore, the applied Q differed between zones

for both De-Icing and Anti-Icing modes of operation.

The same ON/OFF time cycle was applied to each

individual heater zone during De-Icing operation

(except heater zone A which was ON continuously). In

the case of Anti-Icing operation, all heater zones were

ON continuously.

Prior to the test, LEWICE/Thermal and ANTICE were

used to estimate the Q values and ON/OFF times

required for the vafidation testing. Because it was not

known how appropriate these values would be, the first

experimental test runs in the IRT were allocated to

"exploring" the validity of these predictions.

Therefore, these test runs were labeled "exploratory

runs", and were not considered part of the actual

vafidation process. These exploratory test runs

indicated that initial De-Icing ON/OFF time

predictions required some adjustment (shorter ON

times and longer OFF times). Addilionally, these test

rims facih'tated the fine tuning ofboththeDe-Icingand

Anti-Icing operational procedures which will be

described in the next section. A list of heater Q and

ON/OFF times is given in Table rll for the De-Icing

mode of operation A list of T_, and T.a is given in

Table IV for Anti-Icing operation.

EXPERIMENTAL PROCEDURES

An important part of the validation process involved

the development of experimental procedures. This was

necessary not only to ensure consistency in execution

of the validation tests, but also to provide a means of

later reconstructing how the test was actually

conducted. Two distinct procedures were developed:

one for De-Icing tests, and another for Anti-Icing tests.

Both of these procedures make reference to the TrMs

(Test Thermal Management System) which was

developed by Cox & Company to conduct thermal ice

protection system testing. The TTMS performed the

combined function of a data acquisition system, and a

heater power distribution/control system. It was

utilized to acquire all of the thermal sensor data f_m

the test article, as well as provide closed-loop power

control to all of the heater elements on the test article.

De-Icing Test Procedure

• Select icing tunnel T_, airspeed, and spray

conditions

• Start fan and allow tunnel to reach temperature

and airspeed setpoint

• Select ON/OFF lime and program into TFMS

• Select heater flux (Q) for each of the 7 heater

zones, and program into TrMS

• Setup TFMS so as to provide that Q to each heater

zone (constant Q mode)

5
• Simultaneously, perform the following:

Iniliate icing spray

Initiate heater cycling sequence starting

with OFF time

Start data acquisition process

Start video & Infra-Red camera recording

process

• After 5 de-icing cycles, stop spray, heater cycling,

data acquisition, and video recording

• Stop fan, and enter tunnel to take photographs and

rivulet measurements

• Clean ice from test article & go to next condition

h the De-Ici_ mode of operation, the parting strip

was ON continuously. The vew first heater cycle was

initiated (simultaneously with the start of the icing

spray) by waiting a period of lime equal to the OFF

time. Then power was simultaneously applied to zones

B&C for the ON time. Immediately after the ON time

had elapsed for zones B&C, power was simultaneously

applied to zones D, E, F, &G for the ON time. After

waiting for the OFF period of time (relative to zones

B&C), the entire sequence then repeated itself. This

typical heater zone sequence is illustrated in Figure 7,

for an ON / OFF time sequence of 10 seconds ON / 110

seconds OFF.

Anti-Icin_ Test Procedure

• Select icing tunnel T_=, airspeed, and spray

conditions

Start fan and allow tunnel to reach temperature

and airspeed setpoint

Select evaporative surface temperature (T._,), and

program into TI'MS

Setup TrMS to control each heater zone to T_p,

using the abrasion shield temperatures to sense

Tevap (constant Temperalme mode)

• Initiate TrMS controlled application of heat to the

test article in constant Temperature mode

• Initiate icing spray

• When abrasion shield tem_ramres stabilize at

T_p, switch to constant Q mode

• Set Q to value given by constant Temperature

mode of operation, then adjust Q until abrasion

shield sensors in each heater zone indicate T_p

• Then perform the following"

=_ Start dam acquisition process

Start video & Infra-Red camera recording

process

• After 10 minutes or other specified time, stop

spray, turn off heater power, stop data acquisition,

and video recording

• Stop fan, and enter Umnel to take photographs and

rivulet measurements

• Now repeat all the previous steps at TI instead of

atTmp

• Clean ice from test article, & go to next condition

In the Anti-Icing mode of operation, power was

applied to all heater zones continuously.

RESULTS

Typical temperature sensor results are shown in Figure

8 for a De-Icing test run, and Figure 9 for a "ruuning

wet" Anti-Icing test run. These figures show a timehistory of the transverse temperature profile measured

within a particular heater zone. Three temperature

traces are shown in each plot:

1. Outer temperature - measured by the abrasion

shield thermocouple (very close to actual surface

temlm'aune)

2. Middle temperature - measured by an RTD

(indicatedlower value than the actual heater

temperature, but considered an approximate

representation of the heater temperature)

3. Inner temperatme - measured by a thermoco_le

on the inner surface of the insulation

(representative of insulation temperature)

During the course of testing, itwas noticed that one

side of the test article (C, E, G) exhibited more frozen

rivulets aft of the heater zones, than did the other side

(B, D, F). Upon investigation, it was determined that

during the fabrication process, the heater zones had all

been slightly shifted toward the side with heater zones

C, E, & G by 0.1875 inches. This shift had a

significant effect on the parting strip heater (zone A),

which was originally centered with 0.375 inches on

each side of the hi-IRe. The fabrication shift placed

0.1875 inches of heater zone A to the (13, D, F) side of

the hi-lite, and 0.5625 inches to the (C, E, G) side of

the hi-rite. This resulted in more thermal energy being

imparted to the impinging water on side (C, E, G),

than side 03, D, F). This add/tional energy resulted in

more frozen runback beyond the aft heater zones F_.&G.

Photos of f_zen nmback on both sides of the test

article are shown for a De-Icing test run in Figure 10.

These photos were obtained at the end of a De-Icing

run at icing test condition 2, which had a relatively

high LWC of 1.1 g/m 3 (V= 100 mph). This condition

was chosen, because the high LWC better illustrates

that there was more runback on the side with heater
zones(C,E, G). Sincethemajorityof thevalidation

testswere conductedat a LWC of .78 g/m 3

(V=100mph), the difference in runback was not this

pronounced.

VALIDATION PROCESS

To account for the test article heater shi_, the

computer code input geomeUy files were specified to

reflect the actual heater zone locations.

LEWICE/Thermal and ANTICE predicted temperature

profiles were then compared with the measured

temperature profiles.

The primary method for validating LEWICF_,/Thermal

and ANTICE was via comparison of experimentally

measured and predicted temperatures within the

leading-edge structure. As shown in Figure 6, there

were sensor locations within each of the 7 heater

zones. At each of these locations, temperature sensors

were installed within the heater layup to provide a

tran_erse temperature profile at that location. It is the

measurements from these sensors that will be utilized

to vafidate the transient predictive capability of

LEWICE/I_rmal, as well as the steady-state

predictive capability of ANTICE. A full discussion of

the results of these comparisons is beyond the scope of

this paper, but will be given in references 3 and 4.

SUlVEVIARY

The first in a series of NASA Thermal Code Validation

tests was successfully completed. A large experimental

database was generated using a test article with an

electro-thermal ice protection system. Thermal data

were acquired over a range of icing and ice protection

system parameters for the purpose of validating the

electro-thermal predictive capabilities of

LEWI_rmal and ANTICE. The validation was

accomplished via the direct comparison of

experimental and predicted temperatures.

A slight misalignment of the heater zones was

identified during validation testing. All heater zones

were shifted by .1875 inches toward the side with

heater zones C, E, & G. This resulted in more frozen

nmback aft of the heater zones on side (C, E, G). The

validation process accounted for this by modeling the

shift, and then comparing the "heater shifted"

temperature predictions with experimental

measurements.

The code versions validated were LEWICE/Thermal

version 1.7 and ANTICE version 1.13. Detailed

comparisons of experimental and predicted results are

contained in the following reports:

"Validation of NASA Thermal Ice Protection

Computer Codes: Part 2 - The Validation of

LEWICE/Thermal"

"Validation of NASA Thermal Ice Protection

Computer Codes" Part 3 The Validation of

ANTICE."

Future plans include compilation of the Thermal Code

Validation Dam on a CD=ROM. This CD-ROM will

contain: "raw" data and index, validated versions of

LEWICE/Thermal and ANTICE, Thermal Code

Validation reports, and detailed results from selected

comparisons of experimented data and code

predictions.

ACKNOV¢-LEDGEMENTS

Completion of the first Thermal Code Validation test

was made possible by the collective efforts of many

individuals. The authors would like to express their

appreciation to:

• Cox & Company, Inc. for designing and

fabricating the test article

• Each of the industry partners for providing

technical guidance

• The Icing Research Tunnel crew for their

technical support and operation of the icing tunnel

• Mr. Charles Andracchio and Ms. June Thompson

for configuration and programming of NASA's

ESCORT data acquisition system

• Mr. Jay Owens, and Mr. James Sims for their

photographic imaging expertise, and operation of

the Infra-Red camera system

• The NASA Icing Technology Branch for

analytic_1 and experimental technical support

REFERENCES

,

.

Masiulaniec, ICC., Wright, W.B., Users Manual

for the NASA Lewis Ice Accretion / Heat Transfer

Prediction Code with Electro-Thermal De-Icer

Input, NASA CR-4530, July 1994.

AI-Khalfl, K.M., Development of an Anti-Icing

Runback Model, AIAA Paper 90-0759, January

1990.
.

.

Wright, W.B., A1-Khalil, K.M., Miller, D.I_,

"Validation of NASA Thermal Ice Protection

Computer Codes: Part 2 - The Validation of

LEWICF./rhermal', IAA Paper 97-0050,

January 1997.

A1-Khafil, ICM., Wright, W.B., Miller, D.R.,

"Validation of NASA Thermal Ice Protection

Computer Codes: Part 3 - The Validation of

ANTICE", AIAA Paper 97-0051, January 1997.

. Soeder, 1LH., Sheldon, D. W., Andracchio, C. R.,

Ide, ILF., Sper& D.A., Lalli, N.M., NASA-Lewis

Icing Research Tunnel Users Manual, NASA TM107159, June 1996.

Table I. Temper_tre Measurement Uncertainty

Abrasion Shield

Thermocouple

RTD

Insulation

Thermocouple

Positional Uncertainty

(for nominal heater Q)

Q=5w/in 2

Q= 10w/in 2

Q= !5w/in 2

Q=5w/in 2

Q= 10w/in 2

Q=15w/in 2

Q=5w/in 2

Q= 1ow/in 2

Q= 15w/in2

+/- 1.4 *F

+/- 2.8 OF

+/- 4.2 OF

+/- 0.4 *F

+/- 0.8 *F

+/- 1.3 °F

+/- 1.5 OF

+/- 2.9 OF

+/- 4.4 °F

Data Acquisition

Uncertainty

+/- 1.0 °F

+/- 1.6*F

+/- 1.0 OF

S(_tisor

Uncertainty

+/- 0.1 °F

+/- 1.9 OF

+/- 0.1 °F

Total

Uncertainty

+/- 1.7*F

+/- 2.9 OF

+/-4.3 *F

+/- 2.5 *F

+/- 2.6 *F

+/- 2.8 *F

+/- 1.8 *F

+/- 3.1 *F

+/- 4.5 *F

Table H. Icing Conditions Tested

Icing T_ V LWC MVD AOA

Condition (*F) (mph) (g/m 3) (tan) (degrees)

1 20 100 .78 20 0

2 20 100 1.1 20 0

3 20 200 .39 20 0

4 0 100 .78 20 0

5 0 100 1.1 20 0

6 0 200 .39 20 0

7 20 200 .55 20 0

8 0 200 .55 20 0

9 2O 100 .78 20 -2

10 20 100 .78 20 -4

11 20 100 .90 40 0

12 -22 200 .39 20 0

13 15 100 2.0 20 0

14 0 100 .78 20 -2

15 0 100 .78 20 -4

8
Table llI. Nominal Ice Protection System Parameters Tested- (De-Icing Mode)

Icing Test Run

Condition Numbers

1 18-20,

24-26,

28-30

2 45-47

3 50-52

4 32-34

37-39

41-43

5 55-57

6 60-62

7 64

8 66

9 68

10 70

11 72

12 74

13 86

14 88

15 90

T_ Heater ON/OFF Time

(°F) (seconds)

20 10/110, 7/113, 5/115

20

20

0

0

0

20

0

20

20

20

-22

15

0

0

8

10

7

8

8

7

10/ll0, 7/113, 5/115 5 7 7 7

10

10-12

12

12

10

10-14

16

14-15

12

16

14-20

10 10/110, 7/113, 5/115

10/110, 7/113, 5/115

t_

10/110, 7/113, 5/115

10/110, 7/113, 5/115

10/110

10/ll0

10/110

10/110

10/110

10/110

10/110

10-12

15

14-15

12 16 16 15

15 20 20 15

7 10 10 10

15 20 20 15

5 8 8 8

5 8 8 8

5 8 8 8

25 30 30 15

7 10 10 10

10/ll0 12 16 16 15

10/110 12 16 16 15
Table IV. Nominal Ice ProtoZoa System Parameters Tested- (Anti-Icing Mode)

Nominal Surface Temperatur_ (°F)

Icing Test Run T_t Anti-Icing Zone Zones Zones Zones

Condition Number (OF) Mode of Operation A B,C D,E F,G

1 22 20 115 150 150

38 38 38

2 48 2O

3 53 20

4 35 0

5 58 20

6 63 20

7 65 20

8 67 0

9 69 2O

10 71 20

11 73 20

12 75 -22

13 87 15

14 89 0

15 91 0

Evaporative

Runn_ Wet

Evaporative

Running Wet

Evaporative

Run,in8 Wet

Evaporative

Rnnnin 8 Wet

Evaporative

RunningWet

Evaporative

Running Wet

Evaporative

Rmmin 8 Wet

Evaporative

Smmin8 Wet

Evaporative

Running Wet

Evaporative

RunningWet

Evaporat_

Running Wet

Evaporative

P,_umin8 Wet

Runnin 8 Wet

Evaporative

Running W_

Evaporative

Running Wet

120

37

150

38

160

39

160

39

160

39

95 100 100 100

38 38 38 38

115 150 150 150

35 37 37 35

115 155 155 155

40 40 40 40

100 100 100 100

45 45 45 45

105 135 135 135

39 39 39 39

90 95 95 95

44 44 44 40

115 155 155 155

40 40 40 38

115 155 155 150

40 40 40 40

115 150 150 150

42 42 42 40

95 120 120 115

50 56 56 52

40 40 40 38

II0 170 170 170

47 47 47 45

120 160 160 160

40 44 44 44

10
CORNER

C

CORNER

D

2100 TON

COOLER

K_ING

SPRAY BAR /

CONTROL / I

FIOOM J

[___ 400 MPH TEST

SECTION 6 x 9 ft.

VARICHRON DRIVE

CONTROL ROOM

SHOP

CONTROL ROOM --// L

t CORNER

MODEL I A

ACCESS DOOR J

Figure 1 - Plan view of Icing Research Tunnel.

Figure 2 - Test article installed in Icing Research Tunnel

11
Top View

t Heater /

[ -,...__..__.__._. GuardHeater /] Gc_A _. Zones BDF /_ 5-6"

,.

Test m II =I uI 4----- I Upper Heater / Airflow

Area -2_ - LLI I i Element _

,,,

.........

I I _ Lower Heater Zone Width (in)

IkL I I I Element / zone A = 0.75"

_,...._.___ I zone C = 1.0" zone D = 1.0"

zone E = 1.0"

zone F = 1.5"

zone G = 1.5"

Figure 3 - Test artide electro-thermal heater zone layout.

0.7

,m

o

O

m

O

0.6

0.5

0.4

0.3

0.2

0.1

0.0

O=0

. 0_=2

.... a=4

-4 -3 -2 -1 0 1 2

Wrap Distance S, (in.)

Figure 4a - Collection efficiency (_) for NACA-0012 airfoil.

(Droplet Diameter = 20gtm, V = 100 mph)

12
0.7

e_

m

o

0.6

0.5

0.4

0.3

0.2

0.1

0.0

.-S )

....- " / "..k

-4 -3 -2 -1 0 1 2

Wrap Distance S, (in.)

Figure 4b - Collection efficiency (_) for NACA-0012 airfoil.

(Droplet Diameter -- 20pro, V = 200 mph)

Airflow 1 0.0005"

Item

1

2

3

4

5

k

Material (btu/hr.ft.F)

Heating Element (Alloy 90) 23.7 556

9.4

Density

(lbrn/ft 3)

Erosion Shiled, SS 301 HH 501

Elastomer, COX 4300 0.148 86.4 0"30-+003

Fiber Glass/Epoxy Composite 0.17 112 0.375

Silicone Foam Insulation 0.07 40.5 0-27-+003

Cp

(Btu/lbm.F)

0.092

0.12

Figure 5 - Cross-sectional view of test article composite

leading-edge.

13
I.leatm" Zones IR Camera

Viewing Are-,

G E C A B D F j/ Over-tamp f

1.5" 1" 1" .75" 1" 1" 1.5"

a). UnWrapped Leading Edge

,/ ,/,," _// / / / / / / / / ,_

Typ_-T_"O.hr"t,nm

I

I

I

I

L__J._I _HMt

RTO - "MiddY" tamp Fkac I

I

I

I

I

I

I

Type-T -I'inner" temP

b). Crou,-SectJon atTypicsl

Sensor Location

8hk_d

Heater

Spo_

Glass

Insulation

Figure 6 - Test JulJde instrumentation layout.

Heater Start of Icing Spray

Zone j

F

D

B

A

O

E

G

Heater ON

///_////_/////////.///_ _///_/////////,///_ _///Y//

0 20 40 60 80 100 120 140 180 180 200 220 240 260

T'.ne from start of sequence, (seN=)

Figure 7 - Typical heater cyding sequence (10 sec heater ON/110 sec heater OFF)

14
100

90-

80-

70-

60-

'°

40

_ 30

20

10-

0

Outside Temperature

Middle Temperature

-- Inner Temperature

I ' I I ' I ' I ' I ' I

0 100 200 300 400 500 600

Time, sec.

700

Figure 8 - Measured Temperature (De-Icing Run, Heater Zone F, NASA Run #28).

Tt = 20°F, V = 100 mph, MVD = 20 urn, LWC = 0.78 g/m 3, AOA = 0°

100

90-

.°..°

80-

70-

60-

50-

40-

30-

20-

10-

0 I '

0

Outside Temperature

Middle Temperature

-- Inside Temperature

I ' 1 ' I ' I ' I ' I '

50 100 150 200 250 300 350

Time, sec.

Figure 9 - Measured Temperature (Anti-Icing Run, Heater Zone A, NASA Run #22).

Tt = 20°F, V = 100 mph, MVD = 20 um, LWC = 0.78 g/m 3, AOA = 0 °

15
a). Run back aft of zones C, E and G. b). Run back aft of zones B, D and F.

Figure 10 - Frozen runback on test article aft of heater zones.

(Tto t = 20°F, LWC = 1.1 g/m3, MVD = 20 _tm, V = 100 mph, AOA = 0 °)

16
Form Approved

REPORT DOCUMENTATION PAGE OMBNo.OZOn-01_

p_= ,o_>,.t_=,,donforthe,=>0_ ofinfo,,,_t=_, _ =t_. to.,ia,_o _.._u,_: _._. _,_<,<_ltthet__,o;__ .,,t,=_ns.=,.__..=_?_:,i =<._ _=_"_h,_

gmhedngandmaintainingthedataneeded,andcomp_et0nganorewewmgtheco.emlonotintormazlon._a commemsr.eg_u.ngu,_uuR_,,_o,_,_ _-,.=____,,=-I_._,,_...._,_,, __.

collectionof inlormetion. Includingsuggestionsforreducingthinburden,toWashingtonHeadquartersServices.ulreclo.ratemrQnmrm_.2._t*_ermm_., "n ._gport_i_=_O.,_.m,

DavisHighway,Suite1204,Arlmgton,VA 2221_-4302,andto theOffuoeof Managementand Budget,PaperworkHesuct=onP'roJea(utu_uucml,waSnmgu_n,

1. AGENCY USE ONLY (Leave blank) 2. REPORT DATE

December 1996

4. TITLE AND SUBTITLE

Validation of NASA Thermal Ice Protection Computer Codes

Part 1--Program Overview

3. REPORTTYPE AND DATES COVERED

Technical Memorandum

5. FUNDING NUMBI:H:_

6. AUTI-IOR(S)

Dean Miller, Thomas Bond, David Sheldon, William Wright, Tammy Langhals,

Kamel A1-Khalil, and Howard Broughton

7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES)

National Aeronautics and Space Administration

Lewis Research Center

Cleveland, Ohio 44135-3191

9. SPONSORING/MONITORING AGENCYNAME(S)ANDADDRESS(ES)

National Aeronautics and Space Administration

Washington, DC 20546-0001

WU-548--20-23

8. PERFORMING ORGANIZATION

REPORT NUMBER

E-10602

10. SPONSORING/MONITORING

AGENCY REPORT NUMBER

NASA TM- 107397

AIAA-97--0049

11. SUPPLEMENTARY NOTES

Preparedfor tic 35th A_rospaccScicmccsMeeting & Exhibit sponsoredbythe AmericanInstitute of AeronauticsandAstronautics,Rcmo,Nevada,Jsnuary6-10,

1997. De=taMiller, Thomas Bond, and David Sheldon, NASA Lewis Research Ceaatea';William Wright and Tammy Lmgi_ls, NYMA, Inc. 2001 A_rospae_

Parkway, Brook Park,Ohio 44142 (work funded by NASA Contract NAS3-17286); Kamcl Al-lQ-udil,Cox & Company, Inc., New York, New Yoek 10014; Howard

Broughmn,Cortez I]I S¢_rvic¢Corporation, Clevelmd,Ohio44135.Respons_lc person,Dca_ Miller, organization code5840, (216) 433-5349.

12a. DISTRIBUTION/AVAILABILITY STATEMENT 12b. DI_uHIBUTION CODE

Unclassified -Unlimited

Subject Category 34

This publication is available from the NASA Center for AeroSpace Information, (301) 621--0390,

13. ABSTRACT (Maximum 200 words)

The Icing Technology Branch at NASA Lewis has been involved in an effort to validate two thermal ice protection codes

developed at the NASA Lewis Research Center. LEWICE/Thermal (electrothermal deicing & anti-icing), and AN'rICE

(hot-gas & electrothermal anti-icing). The Thermal Code Validation effort was designated as a priority during a 1994 "peer

review" of the NASA Lewis Icing program, and was implemented as a cooperative effort with industry. During April 1996,

the first of a series of experimental validation tests was conducted in the NASA Lewis Icing Research Tunnel (IRT). The

purpose of the April 96 test was to validate the electrothermal predictive capabilities of both LEWICEfrhermal, and

ANTICE. A heavily instrumented test article was designed and fabricated for this test, with the capability of simulating

electrothermal de-icing and anti-icing modes of operation. Thermal measurements were then obtained over a range of test

conditions, for comparison with analytical predictions. This paper will present an overview of the test, including a detailed

description of (1) the validation process, (2) test article design, (3) test matrix development, and (4) test procedures.

Selected experimental results will be presented for de-icing and anti-icing modes of operation. Finally, the status of the

validation effort at this point will be summarized. Detailed comparisons between analytical predictions and experimental

results are contained in the following two papers: "Validation of NASA Thermal Ice Protection Computer Codes: Part 2-

The Validation of LEWICE/Thermal" and "Validation of NASA Thermal Ice Protection Computer Codes: Part 3-The

Validation of ANTICE"

14. SUBJECTTERMS

Thermal; Ice protection; Anti-icing; De-icing

17. SECURITY CLASSIFICATION

OF REPORT

Unclassified

NSN 7540-01-280-5500

18. SECURITY CLASSIFICATION

OF THIS PAGE

Unclassified

19. SECURITY CLASSIFICATION

OF ABSTRACT

Unclassified

!15. NUMBER OF PAGES

19

16. PRICE CODE

A03

20. LIMITATION OF AB:=;_HACT

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