NASA/TM--1998-208810 FEDSM98-5135

Using Computers in Fluids

Engineering Education

Thomas J. Benson

Lewis Research Center, Cleveland, Ohio

Prepared for the

Summer Fluids Engineering Conference

sponsored by the American Society of Mechanical Engineers

Washington, D.C., June 21-25, 1998

National Aeronautics and

Space Administration

Lewis Research Center

November 1998

https://ntrs.nasa.gov/search.jsp?R=19990008860 2018-05-11T16:57:28+00:00Z
Acknowledgments

The Unix simulators presented in this paper use the XFORMS library of GUI delevoped by Mark H. Overmars,

Department of Computer Science, UtrechtUniversity, The Netherlands, and T.C. Zhao of the University of

Wisconsin at Milwaukee. The XFORMS library is copyrighted by T.C. Zhao and Mark H. Overmars, but can be

used for non-commercial and non-profit purposes. The Windows version of FoilSim was converted from the

Unix version by Bruce Beam of the Lewis Research Center. Copies of the programs and sources

are available on the World Wide Web at http://www.lerc.nasa.gov/WWW/K-12.

NASA Center for Aerospace Information

7121 Standard Drive

Hanover, MD 21076

Price Code: A03

Available from

National Technical Information Service

5285 Port Royal Road

Springfield, VA 22100

Price Code: A03
FEDSM98-5135

USING COMPUTERS IN FLUIDS ENGINEERING EDUCATION

Thomas J. Benson 1

Turbomachinery and Propulsion Systems Division

NASA Lewis Research Center

Cleveland, Ohio, 44135

Phone: 216-433-5920

FAX : 216-433-5802

Email : benson@lerc.nasa.gov

ABSTRACT

Three approaches for using computers to improve basic

fluids engineering education are presented. The use of computational fluid dynamics solutions t,o fundamental flow problems is discussed. The use of interactive, highly graphical

software which operates on either a modern workstation or

personal computer is highlighted. And tinally, the develol>-

ment of "textbooks" and teaching aids which are used and

distributed on the World Wide Web is described. Argumenls

for and against this lechnology as applied to undergraduate

education are also discussed.

INTRODUCTION

The use of personal computers and workstatious

in undergraduate fluids engineering education is a relatively recent development, qhe earliest efforts (Koening

and Hodge, 1993; Fox and McDonald, 1992; aml Mattingly, cl.al., 1987) centered around the use of software

developed for personal conlptlters. \Vith lhese packages, students type input conditions at the keyboard

and are presented with principally nunierical output.

The XFOIL program of Drela (19_4.q) was one of the first

efforts to use graphical output fi'om early mini computers. As the nlini COlii[)llt.e'r evolved into the workstation,

alid the personal coiiil)Ul,er was develol_ed, tile operatiug systeni and olitpill frolll these lliachines I)ecaliie

1t'b:st_trch Eng]t_._r

more graphical and visual. Vision is the niost perceptive sense used in education which makes the conlpiller

particularly well suited for fluids educal, ion. }teceut effl)rts by Torella (1,q,q4) and Benson (1994, 1995a. and

1995b) have included a graphical user interface (Girl)

to enhance the iliieractiou between the strident and tile

compllter. With these packages, Stlldents use a lilOllSe

and keyboard to vary inl)llt Colldilions al/d receive principa, lly graphical output. Most receully, Reed alid Afjeh (1997) and l)evenport and Mason (1998) have developed software packages which execute ou the Worhl

Wide Web aud are accessed by a personal computer using a browse]'. An excellent listing of educational software for thiids engineering students has been created })y

Mason alld (Irisafulli (1995).

(?otuputational fluid dynaniics ((_FD) is taught at

most lna_ior universities as part of a fluids engineering

education. CFD is nornially introduced to graduate students, Briley and Hodge (1995), and Lee, Diao, and

Green (1995), for exalnple, but lilay sooli fie included

in some undergraduate studies. The chief argunient tbr

introducing (IFD to undergraduates is that most fluids engineering graduates will be required lo perforni

a (!FD analysis sonietinlein their career. (IFD results

are a function of many factors, inchiding the algorithm

used, the uuliil)er and distributioii of grid poilits, and

the turbulence model. ]_o perforni a nieaningful ('FI)

aualysis, tile studelil, nlusl hay(' some knowledge aud experience in all of these factors. Therefore, lhe subject

NASA/TM-- 1998-208810 1
Figure 1. CFD RESULTS FOR KARMAN VORTEX STREET

should be introduced in the undergraduate curriculum.

The counter argument is that the undergraduate curricuhmi is already tinie limited, and the time is better

spent learning fluid dynamics than coniputational fluid

dynamics. To be able to recognize a bad (!FD answer, a

tluids engineer nlust, haw_ a t,horougli knowledge of fluid

dynamics. Whether (!FD is taught to undergraduates

or not, ('FD may have a place in undergraduate studies,

as discussed below.

This paper will discuss educational software tools

developed by the author in the last five years and intended as SUpl)leinenls ['or laboratory or leer ure courses.

The progranls are designed to act like a desk top laboratory which the student uses to develop a feel and an

umlerstamling of fluid n]echanics. But unlike normal

laboratories, the student can use these tools as often and

wheuever one pleases, with little supervision, It¢) physical danger, and at little expeuse. When incorporated

into a lecture course, the tools call be used for homework exercises which consider many different configuralions and that are otherwise too numerically intensive

['or a st udenl to perfornl in a reasonal>le antount, of time.

Tile develol)nient and distribution of this software has

I:,eell SUliporled by the Learning Technologies Project of

the lligh Performance (!ontputing and ( 'ommuuications

I'rogram within NASA. The main objective in this el'-

fort is res,'arch; to find out what can be done with high

imrfornlance coniputers and workstations. The source

for all the software is in tile pulllic doniain aud may be

furlher dew'lol>ed inlo couiiiiercial packages,

CFD RESULTS

Siiice the adveul of the superconlputer, niany higilly

detailed three dilnensional flow caiculatious have been

l)erfornied and the reslllts presented at, t,echuical lUeelings using COlllputer grapllics or video 1.ape. Ffecause

the two l.rocesses of produciug the results and analyzing the results are separate, an undergraduate cau study

the basic physics of certain ttow l)roblenis without first

learning all of the intricacies of (TD io prodnce tile restilts. Tile flow fiehls (:all be conlput.od I>y a CFD expert.

All that is required for stlldellt, analysis of (TD results

is a workgt at.ion, a graphics package, tile conipuled data

sets, aud sonie experience with the software and hardware. Tli_ hardware and soft.ware issues are constantly

evolviug, but niost universities currently have access t.o

graphics ,:oinputers and graphics packages. Findiug the

data sets to analyze can be a much more serious probleni. The problem can be solved oil an individual basis

by professors preparing the data sets for the student,

or by flu:ling available data sets through a literature

search or all hiternet broadcast. The probleni can also

I>e solved through a group effort. Through the sponsorship of a "entral agency (professional society or governn]elil lab I, CFD professionals can compute basic fluid

niechanics flow fields and make the results available to

the educational conununity. The selection of an appi'opriate pl',)blen] for study can I)e provided t)y tlie user

couunuuit.y. The results of the fundaniental flow calculations can also I)e provided as video tapes for classroom

use.

To d'nioustrale seine of the possibilities of usiug

('Pl) results for fluids engiueering education, a video has

been prel,ared which shows iu great detail the periodic

vortex shredding front a circular cylimler, the 1,/arman

vortex st-eel. Figure 1. shows a still i>iclure froln the

vith'o. Tie calculalion of the tlow fMd was perfornied

t;y Kinl ; ud l-lenson (1992) as part of a code developlnent alid validaliou study. The flow is inconll)ressible,

at. Reyno!ds nnniber of 100 based OU frec streanl w'locil.y

and cyliu ler dianiet,er and the calculal.ed St, rouhal nuinber is .1(]. The video was prepared ai tile NASA Lewis

NASA/TM-- 1998-208810 2
tR/-ltl/_

N/_A LewisReseaf¢hCenter Version6,]b

AnintemctivesimulatortostudyUbojetsandtu_olans,

Thissimulator hasa_l_ty ofspecial featuresavJableto5_muserwhlchare

accu_dby¢ik_ the1JUrOpliofls' _ MJr]ontotherl_lL

UserOptions

AuxMach Input: AJtF Type: (,Turbofan _nri 0 Separate rn Nozzle.) _ ti

'y FuelHV [ 18600

TemperatureLimits:

TIT I 3500 EGT [ 3000 AB

TIT [ 3000

EGTi 2260

CPR r 600 ._

FPRI" 2.00 rx]

BPR [ 1.00

A2 r 4.00

i 0.26 r.]ol

_;mal

2 81' 3 4 5c 5f 6 7 8

Figure 2. VU-TURBOINTERACTIVE FLOW SOLVER

(;rapldcs and Visualizat ion Laboratory using FAST, the

Flow Analysis Software Toolkit, (Walalka ct.al. 1994).

This flow field is time dependent and the video allows

tile student t.o visualize the flow field changing with

t inle. The video presents the sa]ne flow fiehl in several different ways; velocity vectors, streamlines, part ich" traces, color-tagged particles, vorticity contours,

and injecled fluids. Each of the different representations present the viewer with information not available

in tile other representations. 1:or inslance, the particle

traces shown in tile figure demonstrate the formation

of the top and bottom allernately shed vortices. In the

video, the mixiug of the flow al the rear of the cylinder

is quite apparent. Color is used extensively ill the video

to highlight various features. ('ombining all of the dif

ferent representations, the s|.ll(lellt. ('all COllie t,o a better

intuitive understanding o[" this physical process than is

available from any one presentatiol_, or from a text ])ook

picture.

INTERACTIVE SOFTWARE

Interactive educational computer software call be

used to invoh'e tile student in the learning process. Six

interactive packages, five for Unix based workstations

and one for Windows based personal computer, have

been produced at NASA Lewis which demonstrate various flow l)roblems encountered in an undergraduate

engineering curriculum. The programs perform classic one- or two-dimensional analysis of ( 1 ) compressible

flow past a ramp, (2) flow througll a supersonic exlerhal or mixed compression inlet, (3) flow through subsonic wind tunnel, (4) flow through a turbojet or lurbofan engine, (,5) flow past a Kutta-Joukowski airfoil,

and (6) flow pasl a spinning cylinder. Figure 2 shows

a screen dump of the (Tnix based \:isual Undergraduate i)rogranl for TURBOjets (VIT-TUI_BO, Benson.

199($), while Figure 3 shows a screen du]np of the I)( '

Windows program FoilSim. All six programs are built

around a graphical user inlerface: as the input, conditions are changed, the package COml)Ules the new outNASA/TM-- 1998-208810 3
Airfoil View I::'e.nel

000238

Airfoil Input Panel

_oo _ _._ _

o

o.o

Plotter View Panel

Prob_ Control Plotter Control Panel

_:i_:!iiiii!iiii_il

:!iiii_!ii_i_i_:_ i

Figure 3. FOILSIM EDUCATIONAL SOFTWARE

put conditions aml displays the change graphically and

numerically in the output windows. The programs provide the student with an interactiw _ plotter to generate

performance curves, ou-line help, aud lessons prepared

by the teacher which list questions for the student to

answer using the program.

A guiding principal in the development of these educational tools is to do more than just, present answers

to prol_lems: it. is to involve the student in the learning process by having the student work with the package to achieve a resull. ('onsidering Figure 2 as an

exalnple, the student can use this package to design

or analyze a turbojet, a turbojet with afterburner, or

a two spool turbofap engine. The student can select

the design flight conditions (Math number and altitude)

aml set the apl)ropriale design paralneters (turbine inlet

lemperalure, compressor pressure ratio, bypass ratio,

etc.) using either sliders or type-in boxes. As the design parameters are changed, the output screens on the

right shows the variation ill pressure and temperature

throughc tit the engine and the change in the configuration of t.t e engine. Additional outpul screens show perfornlanc¢ parameters, such as engine pressure and telltperature ratio, thrust and fuel consumption. Through

these visual output results and the control of the input

condit.iol_s the student learns how an ideal jet engine

operates and performs.

The teacher, of course, l)rovi(les the student, with

the theory and equations governing all ideal jet engine

(Braytot cycle analysis) as part of the normal course

work. 3_"_e teacher can now have the student compare

the result, of the student's hand calculations with the

results flora the simulator. The |,eacher can also have

the studen! analyze an existing l urbojet and compare

the results of actual turbojet, the student's calculations.

and the output from this computer tool. This introduces some of the ideas of code verification, comparison

of analy,,-es, and probably produces some interesling disNASA/TM-- 1998-208810 ,1
cussions of wily the answers disagree. Tile program Call

also be used as part of a senior design class, to allow

students t.o develop their own performance malls tbr a

theoretical jet. engine.

Figure 3 shows a screen dump of the Windows

[>ersonal colnputer prograln FoilSinl which was derived

froln the Unix progranl VU-FOIL (Benson, 1997). The

analysis in VU-FOIL and FoilSinl is the classic conforlnal lnapping from flow around a cylinder to flow about

a Joukowski airfoil with Kut, ta condition. VU-FOIL is

intended for undergraduates and allows tile Sllldent t,o

vary all the parameters involved ill the analysis; FoilSim

is intended for high school students and hi<les most of

tile complex lnathenlatics. FoilSiln displays the variation of lift with velocity, altitude, angle of attack, camI>er, thickness and wing area. The package inchldes a

l>rot>e which call be ll|oved around the airfoil giving the

local value of w_locity or pressure and on-line lessons

which describe the effects of the various l>arameters and

poses questions which the student call answer by using

tile prograln. There is ew_n a simulation of flow around

a spinning baseball in whMl the student can vary the

sl>eed, spin and air density (location of tile stadium) and

see lhe resulting trajectory fronl the pitchers mound to

home plate. The major intent of FoilSim is t.o increase

student interest with science and inath by l>roviding all

educational video game.

TEXTSITES

Another way to use COlnputers ill fluids engineering

education is t.o provide textbooks over the World Wide

\¥eb ill tile fornl of iexlsites. A t.extsit.e is a group of

pages written in hypertext which are prepared by an

educator t.o teach seine subject.. A [,ext, sile ilwludes information currently found in standard textbooks bill

presents it ill a way wllich utilizes the power of the

V_:eb; a page can inchlde nlany linked references t,o other

l>ieces of information, sophisticated colnputer graphics,

niovie, or audio sequences. A text,site call be I>repared

t>y a single professor, or linked to nlany other professor's

work around the worhl. Tile ,nediunl lends itself to the

presentation of information in ways lhal are not availaide on the printed page; for instance, unsteady flows

can be shown with on-line movie sequences. A t.extsite

can [>e ul>daled as required t.o reflect t.he latest area of

inleresl, ill fluid mechanics.

There are sonic quest.ions which need to be addressed before l.exl.siles rel>la<'e text.books. The lnOSt.

obvious questions involve the site: the l>reparer, topic.

cost of operalion, mainlenance, updating, and cost of

preparations. There arc also major sludent (user) (tuesLewis g{_::_i:

The L#_ Equ=|iorl Research _!_::_i:

i-_iii_iii_iiii

iliiiiiiiiiiiii

L = CI x r x V__2x A

2

Lift -¢oelficienl i densily x velocit'/squared x wing area

two _:!!!

Coefficient Cl contains all the complea dependencies

and iS usually determined experimentally, ii;iiili

+_i!ii+

:_...%%{!:.{i _g-;'+'£! { , +

Figure 4. SAMPLE FROM AIRPLANE AERODYNAMICS WEB SITE

t.ions lo consider: availability of resources (computer,

well browser, server, ..), cost, security, and individual

versus teanl interactions. There are surely nlany other

quest, ions which have not been considered. The quest.lolls and their answers call only I)e idenlified through

experinlenlalion with the technology.

To explore the lecllnology involved witll creat.ing,

maintaining, and el>crating a text.sile, the Learning

Technologies Project at NASA Lewis has established

a site dealing with airplane aerodynanlics. The site was

originally conceived to help high school teachers who

acquired the FoiISim i>rogranl; recognizing thai high

school math and science teachers are not aerodynanlicists. A salnph" page front the site is shown Oll Figure

,1. The teachers were interested ill obtaining copies of

t.he graphics for use in their own classrooms, so each

l>agr is arranged with a topic slide al Ill<' lop and an

explanation of content I>elow. Many of the topics are

interwoven; a page describing parts of all airplane links

to a l>age descrilfing Ill+' operation of the rudder, which

links to a page on the effect of shal,e Oil lift, whMi links

to a page on t,h<' lifl fo,'ce, which links to a page on

wings, and so forlh. ()n lnOSt ]>ag,,s, there are also links

to leer," detailed lh,'orel.ical descril_tions of the infornlation. So the user of the sit<' call obtain a l+road sl>an of

information on a topic, or ol>tain soni<, del>t h of infornlalion on the sanietol)ic. For this sit<', t.ho user starts at

NASA/TM-- 1998-208810 5
the highest level (full aircraft) then works down to tile

theory. For a fluids engineering textsite, t.he professor

may choose to begin with the underlying theory, t.hen

work tip l.o [|ow various components work. A single,

well-desigm'd sito can be used both ways.

SUMMARY

lligh speed COlnputer mainframes, personal computers, aml workstations coupled with interactive operating systems and computer graphics provide many

opportunities for new techniques to teach basic fluid

mechanics. This paper has presented three ways in

which l.he llew technologies can be utilized including

the use of the results of CFD calculations, the use of

interactive flow sinmlators, and the creation of webhased textbooks. Examples of these approaches have

heen presented along with discussion of some possibl,'

problems in their implementation.

REFERENCES

Benson, T.J.. 1994, "'()n the Use of (_Omlmters for

Teaching Fhtid Mechanics", NASA TM 1t16587.

Benson, T.J., 1995a, "'A Workstat.ion Based Smmlator for Teaching (_ompressible Aerodynamics", AIAA

Paper 95-0070,

Benson, T.J., l.q.q,Sb, "'An Ilm'ractive Educational

Tool for Turbojet Engines", AIAA Paper 95-3055.

Benson, T.J., 1996. "'Interactive Educational Tool

for Turhofan and Aftertmrning Turbojet Fngines",

AIAA Paper 96-2561.

Benson, T.J., 1997, 'qnteractive Educational Tool

for (:lassical Airfoil Theory", AIAA Paper 97-0849.

Briley. W.R, aml Hodge, B.K., 1995. "i_, (TD

P,'o.iect ('ombining Solution Algorithnm, Software DeVel()l)tlllqlt, and Viscous Flow ('alculatious", FED-Vol

220, Instructional Fluid I)ynamics, ASME 1995, pp. 7-

12.

Drela, M., 1989, "'XFOIL: An Analysis and Design

System for Low Reynolds Number Airfoils", Con|_rence

on Low F_eynolds Number Airfoil Aerodynalnics, University of Notre Dame, ,June 1989.

l)evenport, W.J. and Mason, W.tt., 1998, "Applied

Aerodynamics Education: Development and Opportunities" subnfitted to A1AA 16th Applied Aerodynamics

( :onference.

Fox, R.W., and McDonald, A.T., 1992, lntroduct*on

to Fluid M¢chan*cs, John Wiley, New York, 4th ed.

Kim, S.-W. and Benson, T.J., 1992, "(:omparison of the' SMAC, PlSO, and lterative Time-Advancing

Schemes for Unsteady Flows", Journal of Computers

and Fluids, Vol. 21, No.3, pp. 435-454.

Koenmg, K. and Hodge, B.K., 1993. "A Suite of

Personal Computer Programs to Support Propulsion

Education", AIAA Paper 93-2053.

Lee, S.C., I)iao, Q. and (;teen, B., 1995, "'Instructional Fluid Dynamics in Viscous Flow", FED-Vol 220,

Instructional Fluid Dynamics, ASME 1995, pp. 35-46.

Mason, W.tl. and Crisafulli, P., 1995, "'Aircraft

l)esign ('ourse (!omputing Systoms: Experience and

Software Review", ASEE Annual (:onference, Anaheim,

(:A.

Mattmgly, J.D., Heiser, W.It. and Daley, D.II.,

1987, Aircraft Enq*_,¢ Destgn, AIAA Education Series.

Washmglon, D.( :.

Reed J.A., and Afjeh, A.A., 1997, "'A .lAVA Simulator for Feaching Gas Turbine Operation", AIAA Paper 97-0850.

Torella. G. and Lomt)ardo, (;.. 199,t, "('Oml)Uler

(k)des fir the Training on Auxiliary Power Units

(A.P.U.)', AIAA Paper 94-3113.

Walatka, P.P, (:lucas, d., McCabe, I{.K., Plessel,

T. and Potter, R., 1994, q"AST User's (;tilde", NASA

Ames Research (lenter, NAS Division, RNP Branch.

NASA/TM-- 1998-208810 6

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November 1998 Technical Memorandum

4. TITLE AND SUBTITLE

Using Computers in Fluids Engineering Education

6. AUTHOR(S)

Thomas J. Benson

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

National Aeronautics and Space Administration

Lewis Research Center

Cleveland, Ohio 44135-3191

9. SPONSORING/MONITORING AGENCY NAME(S) AND ADDRESS(ES)

National Aeronautics and Space Administration

Washington, DC 20546-0001

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REPORT NUMBER

E- 114(X)

10. SPONSORING/MONITORING

AGENCY REPORT NUMBER

NASA TM I 1998-208810

FEDSM98-5135

11. SUPPLEMENTARY NOTES

Prepared for the Summer Fluids Engineering Conference sponsored by the American Society of Mechanical Engineers,

Washington, De, June 21-25, 1998. Responsible person, Thomas J. Be 1son, organization code 5880, (216) 433-5920.

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This publication is available from the NASA Center for AeroSpace lnlbrmation. (3t71) 621-0390.

12b. DISTRIBUTION CODE

13. ABSTRACT (Maximum 200 words)

Three approaches for using computers to improve basic fluids engineering education arc presented. The use of computational fluid dynamics solutions to fundamental llow problems is discus,,ed. The use of interactive, highly graphical

software which operates on either a modern workstation or personal cotnputer is highlighted. And finally, the development of "textbooks" and teaching aids which are used and distributed on the World Wide Web is described. Arguments for

and against this technology as applied to under,,ra= • duate education are aiso discussed.

14. SUBJECT TERMS

Aerodynamics: Fluid mechanics; Computational fluid mechanics Education:

Computerized simulation

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