Document
NASA-TM-86921
J9fo(JtJt) 116-g
NASA Technical Memorandum 86921
AIAA-85-0314
The Altitude Wind Tunnel (A WT)-A
Unique Facility for Propulsion System
and Adverse Weather Testing
Roger Chamberlin
Lewis Research Center
Cleveland, Ohio
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Prepared for the
Twenty-third Aerospace Sciences Meeting
sponsored by the American Institute of Aeronautics and Astronautics
Reno, Nevada, January 14-17, 1985
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THE ALTITUDE WIND TUNNEL (AWT) - A UNIQUE FACILITY FOR PROPULSION SYSTEM AND ADVERSE WEATHER TESTING Roger Chamberlln Natlonal Aeronautlcs and Space Admlnlstratlon Lewls Research Center ~ Cleveland, OhlO 44135 Summary The only wlnd tunnel In thlS country for conductlng lClng research lS the IClng Research Tunnel at the A need has arlsen for a new wlnd tunnel facll- Lewls Research Center. ThlS faclllty, whlle heav- lty wlth unlque capabllltles for testlng propulslon lly used and a very valuable tool, lS small and has systems and for conductlng research In adverse only low-speed capabllltles. ThlS tunnel does not weather condltlons. New propulslon system con- permlt englne operatlon nor slmulate altltude cepts, new alrcraft conflguratlons wlth an unprece- pressure.
dented degree of propulslon system/alrcraft lntegratlon, and requlrements for alrcraft opera- Future Aeronautlcal Systems tlon In adverse weather dl.Gtate the need for a new test faclllty. Requlred capabllltles lnclude Slm- Some of the new alrcraft systems that are ulatlon of both altltude pressure and temperature, expected to evolve In the future are llsted In large Slze, full subsonlc speed range, propulslon Flg. 2. These new alrcraft systems wlll lncorpor- system operatlon, and weather slmulatlon (l.e., ate new or modlfled types of propulslon systems, lClng, heavy raln). A cost effectlve rehablllta- somewhat dlfferent than those currently In serVlce.
tlon of the NASA LeW1S Research Center's Altltude Future systems wlll lncorporate propulslon concepts Wlnd Tunnel (AWT) wlll provlde a faclllty wlth all WhlCh wlll be more efflclent, and WhlCh wlll not these capabllltles. only develop thrust, but In some appllcatlons wlll also produce 11ft. In other appllcatlons the pro- Introductlon pulslon system wlll be used as an ald for alrcraft stablllty and control. These new conflguratlons Future new alrcraft and propulslon systems wlll wlll requlre alrframe and propulslon system lnte- requlre wlnd tunnel test facllltles wlth unlque gratlon to a degree of SOphlstlcatlon far beyond capabllltles that currently are not avallable In any current systems.
thlS country.l,2 Future alrcraft of all types, C1Vll and mllltary, wlll place lncreased emphasls There lS an lncreaslng need, for productlvlty, on propulslon system lntegratlon, both the propul- mlSSlon effectlveness, and survlvablllty, to oper- Slon system wlth the alrframe, as well as between ate at wlll In all types of weather condltlons (lclng, snow, heavy raln). Mllltary operatlons propulslon system components. Future emphasls wlll also be placed on lncreased alrcraft operatlonal are, of course, not llmlted to areas or seasons of capabllltles, WhlCh means operatlng In adverse favorable cllmatlc condltlons. C1Vll alrcraft must weather condltlons. These factors wlll requlre operate year round and In all parts of the world, and therefore frequently encounter adverse weather wlnd tunnel facllltles that are large, slmulate true altltude condltlons (lncludlng temperature), condltlons. Current transport alrcraft have some permlt the operatlon of a propulslon system, and lce protectlve devlces, but future alrcraft wlll can slmulate adverse weather condltlons. There lS lncorporate dlfferent features such as zero bleed no large scale wlnd tunnel In the Unlted States or englnes and composlte materlals etc., that wlll not the free world that provldes these capabllltles. permlt the use of the klnds of protectlve systems The Altltude Wlnd ~unnel (AWT), located at the NASA used on eXlstlng alrcraft. New protectlon systems Lewls Research Center In Cleveland, OhlO, could be wlll have to be developed and thlS can only be done modlfled In a cost effectlve manner to provlde all wlth a thorough understandlng of the entlre of these necessary capabllltles. alrcraft/propulslon system when operatlng under reallstlc envlronmental condltlons.
A blue-rlbbon commlttee was formed In 1982 to reVlew the natlonal aeronautlcs research and tech- In recent years the prlce of alrcraft fuel has nology pOllCy.3 The flndlngs of the commlttee stablllzed. However, It stlll represents a Slze- are summarlzed In Flg. 1. Slgnlflcant galns In • able portlon of the alrcraft dlrect operatlng cost, alrcraft and alrcraft propulslon system performance approxlmately 50 percent, and It 15 probable that are yet to be made. The study concluded that fuel prlces wlll rlse agaln at sometlme In the numerous opportunltles eXlst for maklng dramatlc future. Therefore energy efflclency lS stlll leaps In technology. Indeed, all currently opera- extremely lmportant to the alrcraft/alrllne lndus- tlonal mllltary and C1Vll alrcraft could be tech- try. One of the propulslon system concepts cur- nolog1cally superseded by the end of the century. rently belng evaluated for slgnlflcantly reduclng Whlle advances are posslble, achlevlng them wlll transport alrcraft fuel consumptlon 15 the hlgh- not be easy and advanced fllght vehlcles wlll speed turboprop (Flg. 3). Through approprlate requlre a conslderable degree of propulslon system/ technologlcal advancements, thlS concept has the dlrframe lntegratlon. Integratlon of aerodynamlcs, potentlal to reduce alrcraft fuel consumptlon by 20 rnaterlals and structures, and propulslon wlll play to 30 percent compared to the best state-of-the-art an lncreaslngly lmportant role In the development turbofan englne. Fuel savlngs of thlS magnltude of future mllltary and C1Vll alrcraft. These new would slgnlflcantly lmprove alrllne carrler proflt- hlghly lntegrated systems wlll requlre a new type ablllty and posslbly open up large new world of test faclllty.
markets for short/medlum range alrcraft. The lnte- gratlon of thlS propulslon concept wlth the alr- Operatlon of alrcraft In adverse weather (such frame lS very dlfferent from current turbofan as heavy raln, lClng condltlons, etc.) lS a hazard- lnstallatlons. MaJor advancements In understandlng ous sltuatlon for both mllltary and C1Vll alrcraft.
the phenomena controll1ng the successful 1ntegra- fl1ght. These technology challen~es must be stud- tlon of th1S concept wlll be needed 1n order to led and resolved through systems lntegrat10n real1ze these slgn1f1cant performance 1mprovements. analys1s and exper1ment.
Propuls10n System Integrat10n New h1ghly surv1vable m1l1tary a1rcraft con- cepts (F1g. 4) w1ll present a n~ and complex set Fac111ty Requ1rements of potent1al problems w1th regard to the 1mpact of 1nstallat1on effects on the performance and oper- Many future a1rcraft concepts have propulslon ab1l1ty of the propuls1on systems. For these veh1- systems h1ghly 1ntegrated w1th the a1rframe (l.e., cles, less V1S1b1l1ty to radar detect10n 1S sought where the a1rframe/1nstallat1on has a pronounced by sh1eld1ng or mask1ng the "hard parts" of an effect on the performance of the propulslon enq1ne such as the rotat1ng mach1nery, the "hot system), and 1n some cases 1nvolve new propulslon parts· such as the exhaust nozzles and turb1nes, system concepts such as the h1gh-speed turboprop.
and the hot exhaust gases. Maneuverab1l1ty 1S The propuls1on un1t may be burled w1th1n the a1r- another 1mportant feature of many of these a1r- frame or closely coupled w1th lt and be performlng craft. H1gh maneuverab111ty 1S accompl1shed w1th funct10ns 1n add1t10n to prov1d1ng thrust, such as exhaust nozzles Wh1Ch can be used to deflect the prov1d1ng a1rcraft stab1l1ty and control. Tests of hot exhaust Jet to a1d t~~erodynam1c control the propuls1on system w111 requ1re port10ns of the surfaces. The des1gn 1ngenu1ty needed to ach1eve alrframe to correctly slmulate the 1nstalled enV1- th1S sh1eld1ng and maneuverab111ty generally ronment (F1g. 7). Tests 1n eng1ne test tanks are results 1n complex and tortuous eng1ne a1r 1nlet not suff1c1ent for these h1ghly complex 1ntegrated and eXlt systems such as mult1turn a1r 1ntakes and systems. These new systems requ1re a w1nd tunnel two-dlmenslonal h1gh aspect rat10 nozzles. These test conf1gurat10n Wh1Ch can prov1de the actual co-plex and tortuous a1r lntake systems w1l1 tend 1nternal flow fleld as well as the external flow to accumulate lce mak1ng all weather operat10n f1eld. For example, the rotat1ng propeller of the dlfflcult A total 1ntegrated systems approach to turboprop system 1S closely coupled to the external the analysls and evaluat10n of th1S class of a1r- flow f1eld of the a1rcraft. The external flow must ~raft 1S needed 1n order to opt1m1ze the overall be slmulated 1n order to 1nvest1gate the operatlon of the total system. ThlS d1ffers from current ~erformance.
turbofan or turboJet englnes Wh1Ch have 1nlets to The potentlal for develoP1ng h1gh performance condltlon the flow before It reaches the eng1ne.
JI.d ,afe vert1cal/short take-off and land1ng a1r- craft (V/STOL) (F1g. 5) 1S be1ng explored uS1ng Because the propuls10n system and a port10n of operatIng exper1mental veh1cles and conceptual the a1rframe as well must be tested concurrently, deSlqn studles. The technolog1es needed to cap1- requlres e1ther a large Slze wlnd tunnel or work1ng tallze on the operat1ng flex1b111ty advantages at subscale. Subscale test1ng of system assoclated w1th th1S type of a1rcraft are be1ng performance/1nteract10n 1S not adequate because of explored for lntermed1ate subsonlc speeds uS1ng the the problems 1n Slmultaneously scal1ng aerodynamlc, 'l~SA/Army tllt rotor exper1mental veh1cle and for structural, and mechanlcal behav1or. Also the hlqh subsonlC and supersonlc speeds uSlng des1gn slmulat10n of adverse weather does not scale well concepts emploY1ng deflected Jets and eJector 11ft (d1scussed 1n more deta11 1n the next sect10n).
prlnClples. The need to accurately understand the Therefore, a requ1rement for th1S new fac1l1ty 1S effect of the lnstallat10n on the propuls10n system that 1t be a w1nd tunnel conf1guratlon and large ~hlCh provldes the vert1cal 11ft power as well as enough to perm1t full or large scale test art1cles the forward fllght thrust 1S cr1t1cal to the suc- cess of these a1rcraft. A tYP1cal subson1C fl1ght prof1le 1S shown 1n F1g. 8. The dashed 11ne represents the operat1ng New concepts for rotorcraft (F1g. 6) are be1ng 11ne of a tYP1cal sea level wlnd tunnel. As can ger.erated wlth the emphaS1s on ach1ev1ng much be seen th1S type of fac111ty can only slmulate a hlgher operatlonal speeds (Mo ~ 0.8). State-of- very small port1on of the fl1ght envelope. In a the-art rotorcraft are 11m1ted to low subson1c sea level fac111ty the tests performed at almost fllght speeds due to llm1tat1ons lmposed by the all speeds are at an amb1ent pressure slgn1flcantly large rotat1ng set of blades used dur1ng both ver- h1gher than would be encountered 1n actual fl1ght.
tlcal and horlzontal fl1ght. As forward fl1ght The h1gher pressures result 1n slgnlf1cantly speed lncreases the 11ft to drag eff1c1ency of cur- greater loads on the eng1ne components. In an rent technology rotors 1S slgn1f1cantly degraded atmospherlc tunnel the a1r dens1ty can be as much and structural concerns become ser10US. New ap- as three t1mes h1gher than at true alt1tude, WhlCh proaches, such as the X-w1ng concept where1n the can cause slgn1f1cant changes 1n the aerodynam1c rotor becomes a stat10nary llftlng dev1ce and the performance of propellers, fans, compressors, etc.
advanclng blade concept where1n two counter rotat- The h1gher a1r denslty also results 1n unreallstlc lng rotors are used, have the potent1al for allev1- loadlng patterns on these components Wh1Ch requ1res atlng the current forward fl1ght speed llm1tat10ns the test hardware to have a d1fferent structural of rotorcraft. These concepts have the potent1al character1st1c or poss1bly a d1fferent mechan1cal for expandlng the forward fl1ght envelope of future des1gn, thus mak1ng the test unrepresentat1ve.
rotorcraft to the m1d to h1gh subson1c speed range. Therefore, another fac1l1ty requ1rement 1S slmula- Propuls1on/alrframe 1ntegrat10n technology chal- t10n of the correct alt1tude pressure.
lenges, not present 1n state-of-the-art rotorcraft, must be addressed w1th these new systems. The need In actual fl1ght, not only does the amb1ent to successfully accompl1sh the trans1t10n between pressure drop w1th 1ncreas1ng altltude, but so does shaft power operat10n and Jet thrust 1S cr1t1cal to the temperature. Most of the eX1stlng w1nd tunnels the future success of these veh1cles as 1S the need are not refr1gerated and therefore operate a tem- to deslgn h1gh performance eng1ne 1ntake and peratures slgn1f1cantly h1gher than 1n actual exhaust systems for efflclent h1gh-speed forward fl1ght. F1gure 9 lllustrates th1S d1fference and the lmpact caused by thlS dlfference. A tYPlcal unrefrlgerated wInd tunnel wIll generally op~rate All parts of an aIrcraft are subJect to lClng, at stagnatlon temperatures ln excess of 100 F hot- however, lce accretlon on some components (l.e., ter than true altltude temperatures. In order to propulsIon system, wlng) lS very crltlcal to the achleve aerodynamlc slmllarlty when testlng a pro- alrcraft operatlon. Some of these components are pulsIon system the corrected speed N/~ must be lIsted In FIg. 12. Inlets and carburetors, of the same as would occur ln fllght. If the aIr tem- course, are crItIcal to the operat10n of the engIne perature T, durlng the test lS ~o hIgh, then the and have been shown to be very effIcIent Ice col- rotatIonal speed N must be Increased correspond- lectors. Fans and propellers have sharp leadIng lng1¥. A temperature dIfference between 110 and edges and can collect Ice easIly, wh1ch could d1s- 120 F, as used In thlS exam~le, requIres that the rupt the flow over the blade and cause losses In engIne be oversped by 10 to 12 percent. Overspeed- thrust. New advanced aIrfoIls also are thIn and lng the engIne has several effects whIch can lImIt can accumulate Ice on the 1ead1ng edge and lIttle or InvalIdate the results of the test. An over- IS known about the aerodynamIc penaltIes of these speed of thIs amount would Increase the centrIfugal new shapes as Ice accumulates. The same IS true forces In the rotor, fan, or propeller blades by for rotorcraft.
25 percent. ThIs may requIre uSIng a dlfferent blade constructIon technIque or added strength As mentIoned prevIously, new propulsIon systems bUIlt Into the blades. In eIther case, the blades and aIrcraft desIgns wIll not always permIt the use would have a dIfferent str~etural response than the of Ice protectIon systems of the type used on cur- actual blade desIgn. Also the Increased rotatIonal rent transport aIrcraft. FIgure 13 lIsts some of speed wIll cause the blades to deflect or untwIst the new developments that wIll Impact the operatIon dlfferent1y than deslgned and therefore wlll result of and the klnd of lce protectlon systems that can In a dIfferent shape. Both the Increased centrIfu- be used. The need for Improved fuel effIcIency IS gal loads and the blade untwIst dIfferences can changIng current engIne desIgns and one of those sIgnIfIcantly change the flutter characterIstIcs.
changes IS the reductIon of bleed aIr for auxIlIary In addItIon to the changes In the flutter charac- systems. Hot engIne bleed aIr 1S used for Ice pro- terIstICS of the blades the hIgher rotatIonal speed tectIon on most cIvIl transports. Also new mate- changes the forces from the engIne. The-engIne rIals, such as composItes, are beIng Introduced to would be runnIng at hIgher than desIgn speeds and save weIght, but whIch may not be able to wIthstand therefore operatIng wIth a dIfferent vlbratlonal the hlgh temperatures of the engIne bleed aIr.
sIgnature than the desIgn condItIon. All of these Advanced a1rfol1s desIgned to ma1ntaln large re- factors lead to a test sItuatIon that IS mechanI- g10ns of lamInar flow are sensItIve to the changes cally very dIfferent from actual flIght. There- caused by Ice bUIldup on the leadIng edge. Many fore, another test facIlIty requIrement IS that new aIrcraft wIll have propu1S1on systems hIghly J~blent temperature be correctly sImulated. Integrated wIth the aIrframe. ThIS wIll produce eng1ne Inlet ducts wIth tortuous paths very suscep- The necessary facIlIty capabIlItIes for con- tIble to ICIng. ImprovIng aVlon1CS and gUIdance ductIng propulsIon system IntegratIon research are capabIlItIes encourage operatIon 1n adverse weather surmarlzed In FIg. 10. Currently there IS no fa- as do expandIng m1SSlon requIrements.
cIlIty 1n eXIstence that can provIde all these capabIlItIes Ice accumulatIon and growth 1S a very complex phenomena. The two types of Ice growth, Rlme and Adverse Weather OperatIon Glaze, are depIcted In FIg. 14. These can be very dIfferent and have very dIfferent effects on the To fully exploIt the potentIal of the future flow over the surface the Ice IS accumulatIng on.
energy effIcIent, hIgh performance, survIvable, and Both types of Ice growth, however, are a functIon operatIonally fleXIble aIrcraft requIres that they of a number of dIfferent varIables whIch are lIsted be capable of successfully operatIng In all weather on the fIgure. Many of these are envIronment condItIons (FIg. 11). ContInuIng pressure to related and translate dIrectly Into capabIlItIes expand flIght envelopes, geographIc routes, and that an ICIng research facIlIty must have. Such a flIght frequency, IndIcates that the effects of facIlIty must be a wInd tunnel that can SImulate weather phenomena such as ICIng, snow, and heavy the speed range over whIch Ice can accumulate.
raIn must contInue to be explored and thIS can only Because the Ice growth IS a functIon of the aIr be done under realIstIc envIronmental condItIons. velocIty a large speed range IS reqUIred. The Successfully achIevIng all weather operatIonal cap- facIlIty must also SImulate proper altItude pres- abIlIty In future hIghly survIvable mIlItary alr- • sure and temperature, agaIn because the Ice growth craft, and In current and future rotorcraft IS a functIon of these parameters. An ICIng facIl- requIres a more thorough understandIng of the Ity must also have a method of IntroduCIng mOIsture potentIal adverse effects of weather on these con- Into the aIrstream In a varIety of forms and cepts. Today these condItIons can only be found amounts matchIng what eXIsts In the atmosphere.
V1a costly, t1me consum1ng and rIsky flIght test1ng.
Ice accretIon does not scale wIth the sIze of the surface beIng Iced. ThIS IS demonstrated In Current large transport a1rcraft have some pro- FIg. 15. Smaller obJects are more effICIent Ice tectIon systems wh1ch are effectIve. However, collectors than large obJects. Other factors, such future changes to propulsIon systems and to the as water droplet sIze relatIve to the obJect sIze a1rframe wIll no longer perm1t the use of these and the water content In the aIr, also enter Into eX1stlng systems and new ones w111 have to be the scalIng phenomena. Attempts have been made to developed. In order to perform adverse weather ana1yt1ca11y account for sca11ng effects, but have research, specla11zed facl11ty capabl11tles are been unsuccessful. ThIS IS due to the complexIty requ1red. ICIng research w111 be developed as an of the problem and the scarcIty of experImental IllustratIve example to determ1ne the type of data Because the scalIng pheno~ena IS complex and facl11ty capab111tles needed for adverse weather not well understood It IS necessary to perform testIng test1ng at large scale. Therefore, a requ1rement a1tltude wlnd tunnel for propu1s10n system testlng for an 1c1ng fac111ty 1S that 1t be large enough to for approxlmate1y 15 years. From 1960 to 1970 lt perm1t large scale model test1ng w1thout adverse was used as a space power chamber and has been blockage effects. dormant Slnce 1970.
Currently the largest 1c1ng research w1nd tun- The proposed modlflcatlons to the eXlst1ng nel 1S the NASA Lew1s Research Ce~ter IC1ng facl11ty would result ln the deslgn shown schemat- ~esearch Tunnel (IRT) Wh1Ch has a 6 foot by 9 foot lca11y 1n Flg. 20. The test sectl0n 1S octagonal test sectIon. The IRT 15 heavIly used because of measurIng 20 ft across parallel SIdes. Mach num- lts very un1que 1c1ng capab111t1es, however, 1t has bers rang1ng from near 0 to more than O.g w111 be sone 11m1tat1ons. The IRT 1S a sea level tunnel achlevable w1th large blockage models (10 to and therefore does not slmulate true a1t1tude pres- 12 percent) lncludlng complete operatlng propu1s10n sures. The operat1ng 11ne of the IRT 1S shown on systems. The eXlst1ng central Lewls altltude F1g. 16. The IRT speed capab111ty 1S 11m1ted to exhaust system wll1 provlde altltude var1at10n from J1lues equ1valent to Mach 0.4. As can be seen from sea level to greater than 55 000 ft. The tunnel th1S f1gure there 1S a large port10n of the fl1ght refrlgeratlon system wl11 allow tunnel total tem- envelope where 1c1ng cond1tlons eX1st that no large perature varlatlons from -40 to 60 OF.
test fac1l1ty has the capab111ty of slmu1atlng.
Also 1n F1g. 16 1S a sketc~-of a tYP1ca1 full scale The AWT standard wlnd tunnel components are 1nlet/nacelle/splnner for a turboprop propuls10n shown ln Flg. 21. The drlve power for the fac111ty system mounted 1n the IRT test sectlon. Even WIll be provlded by two 30 000 hp e1ectr1c motors.
though the IRT 1S the largest facll1ty of ltS k1nd, Each can be run lndependently or they can be run ln the test hardware shown would prov1de h1gh blockage serles dependlng on the operatIng requlrements.
levels. The drlve fan wl11 be a hlgh efflclency deslgn wlth two rotor stages each contalnlng 17 blades. The The facll1ty capabll1tles requ1red for conduct- number of stator vanes (28 per stage) was selected nq adverse weather research are summar1zed ln to mlnlmlze the lnteractlons between the vanes and Flq. 17. IClng research has been used as the rotor blades and thus mlnlmlze the nOlse wlthln the 1 1lustratlve example to develop these crlterla, but tunnel. The heat exchanger wl11 provlde coollng to the sa~e capab111tles are what 1S needed for the remove the heat added to the tunnel alr by the uther types of adverse weather as well. There 1S drlve fan and to slmulate the deslred altltude ~o fac111ty 1n eXlstence that has all these neces- statlc temperatures. The flow condltloners wl1l p s 'rj capab111tles for advers weather testlng. conslst of a honeycomb sectlon and removable screens. The screens wlll be removed durlng ad- flew Test Facll1ty Requlrements Summary verse weather testlng. The flow condltloners wl11 provlde good quallty (low turbulence) flow to the The abl1lty to correctly slmu1ate the enV1ron- test sectlon. The octagonal test sectlon lS fltted ~ental and fllght condltl0ns needed to study and wlth boundary layer bleed slots runnlng along each .esolve the technologlca1 challenges assoc1ated of the elght corners. The test sectlon wll1 be ;'th the proposed future alrcraft concepts wl11 be surrounded by a plenum chamber WhlCh can be pumped crltlcal for achlevlng the potent1a1 they offer. down to low pressures to bleed the boundary layer !n order to perform the research necessary to out of the test sectlon to mlnlm1ze tunnel wall develop these technolog1es new test fac111ty cap- lnterference effects.
rb111tles wl11 be requlred (Flg. 18). The new hlghly lntegrated systems prevlously dlscussed wlll The speclal features of the AWT WhlCh help rpqu1re a test facl11ty that has the capablllty of provlde ltS unlque capabllltles are shown ln ~prfornlng tests wlth an actual operat1ng propul- F1g. 22. The turnlng vanes ln the two corners Slcn system and the-propulslon system must operate downstream of the test sectlon wlll be heated.
the sane as lt does ln actual fllght. ThlS ThlS feature lS needed to prevent lce bU1ldup on requ1res correct slmulatlon of both altltude pres- the vanes dur1ng adverse weather testlng. The heat s~re and temperature. Such a fac111ty must be exchanger w11l be connected to a 21 000 ton capac- large enough to accept a full scale propu1s10n lty, Freon-22, two phase refrlgeratlon system.
system as well as a port1on of the a1rframe. In ThlS system w1l1 permlt operatlon at statlC tem- order to properly evaluate lntegratlon effects a peratures that are encountered at altltudes ranglng w1nd tunnel conflguratl0n lS requlred that can from sea level to ln excess of 55 000 ft. The slmulate a broad subsonlc speed range. Approprlate water spray system wl11 be lnserted ln the tunnel accormodatl0ns must be made to permlt the opera- for adverse weather testlng (l.e., lClng condl- t10n of the propulslon system (l.e., an exhaust tlons, heavy raln, snow). Th1S system wl11 have scoop). In order to perform rea11stlc adverse the capabl11ty to lntroduce water ln varl0US drop- "cather research requlres all of the above cap- let Slzes and water content levels. The spray bar )b1l1t1es as well as a means of lntroduc1ng system wlll be removed when not ln use to preserve rOlsture ln the proper amounts and forms (clouds, test sectlon flow quallty for aerodynamlc tests.
n1st, ra1n, etc.). An englne exhaust scoop wlll be lncorporated so that full scale englnes can be operated and tested ln the faclllty. The scoop wlll capture and Altltude Wlnd Tunnel (AWT) exhaust the englne waste products so that the alr clrculatlng ln the tunnel wl11 not be contamlnated.
A proposal has been made to modlfy the eXlstlng dormant Altltude Wlnd Tunnel (AWT) at the NASA The plenum evacuatlon system wlll permlt the use of Lew1s Research Center to provlde a faclllty that large hlgh blockage models at hlgh subson1c speeds.
The boundary layer WIll be drawn off by pump1ng would have all of the requlred capabl11tles for both propu1s10n system lntegratlon and adverse down the plenum. ThlS wl11 mlnlmlze the wall heather testlng. ThlS faclllty, shown ln Flg. 19, lnterference effects and permlts testlng of larger was bUllt ln 1944 and was used as a refrlgerated slzed models. The alr drawn off wl11 be compressed and Injected back Into the tunnel Just downstream conflguratlor also Includes a method for Introduc- of the drIve fan. Plans for thIs facIlIty also Ing mOIsture Into the test sectIon In varIous forms Include acoustIc testIng, and therefore, some and amounts. ComparIsons are also made WIth the acoustIc features have been Incorporated Into the LeWIS ICIng Research Tunnel whIch IS the largest desIgn. As mentIoned before, the vane/blade ratIo and most heaVIly used lClng faCIlIty In thIS coun- try. As can be seen from the plot the IRT IS selected for the fan was chosen to mInImIze nOIse.
A four rIng sIlencer wIll be lo~ed Just down- lImIted to operatIon along a lIne from Mach 0 to stream of the heat exchanger and there wIll be 0.4 at sea level pressures. The AWT confIguratIon, acoustIc treatment In the turnIng vanes and the on the other hand, would cover a very large speed/ walls of the two corners upstream of the test altItude envelope. FIgure 25 also Includes sketches sectIon. The test sectIon wIll have lnsertab1e shOWIng the sIze of the proposed AWT relatIve to acoustIc panels and several dIfferent confIgura- the LeWIS IRT. The sketches show the same lnlet/ tIons are beIng consIdered that would choke the nacelle model mounted In both tunnels. As can be flow at the end of the test sectIon, to prevent seen the blockage In the IRT faclllty would be downstream nOIse from propagatIng forward. WIth qUIte hIgh, however, that would not be the case In all of these features the background nOIse level AWT, In fact, a full sIze propeller (14 ft dIam- eter) could also be Included and operated.
In the test sectIon IS expected to be less than 120 dB.
The abIlIty to correctly SImulate the envIron- DetaIls of the test sectIon are shown In mental and flIght condItIons needed to study and FIg. 23. The octagonal shape provIdes a convenIent resolve the technologIcal challenges assocIated geometry for the use of boundary layer control WIth the proposed future aIrcraft concepts WIll be bleed slots whIch permIts good transonIc perform- crltlcal for achIeVIng the potentIal that they ance WIth large blockage models. The octagonal offer. UnIque ground test faCIlItIes are used to shape also faCIlItates use of flat hIgh qualIty SImulate the needed flIght envIronment and thereby optIcal WIndows for ICIng research and for the use SIgnIfIcantly reduce the tIme, cost, and rIsk that of laser measurement systems. ThIS shape prOVIdes would be assocIated WIth flIght testIng. Ground a convenIent SIdewall deSIgn for easllY·lnstalllng test faCIlItIes also prOVIde the more accurate 3nd lnterchanglng acoustIc p~nels. Model entry measurement systems and more fleXIble test condI- Nl11 be from the bottom of the test sectIon. The tIons that are needed to fully understand complex tunnel floor wlll be mounted on screw-Jacks whIch technIcal phenomena and resolve technologIcal Nl11 a110N It to be raIsed and lowered. The models questIons.
W III be brought onto the tunnel fl oor at the sur- roundlng shop level and then WIll be raIsed Into An evaluatIon of eXIstIng U.S. ground test faCIlItIes has revealed a crItIcal VOId In the place. Models can be mounted from elther the slde- ~a11 trunnlons or a floor plate In the center of capabIlIty to prOVIde the approprIate condItIons the test sectlon. These features WIll allow for for conductIng accurate evaluatIons of the Inte- rapId model InstallatIon and removal from the test grated technologIes assoclated WIth propulslon/ sectIon thereby prOVIdIng hIgh experImental produc- aIrframe IntegratIon and all weather operatIon.
tlvlty. A force balance WIll be attached to the To fIll thIS VOId LeWIS has proposed to rehabIlI- tunnel floor plate to allow thrust measurements of tate and modIfy the eXIstIng dormant AltItude WInd propulslon system performance. A conSIderable ana- Tunnel faCIlIty that WIll SImultaneously satIsfy lytIcal and physlcal modelIng effort IS underway to the test requIrements needed to successfully eval- assure thls deslgn WIll prOVIde the reqUIred test uate and resolve the technologIcal challenges envIronment and performance. ,b assocIated WIth future hIgh potentIal aeronautIcal vehIcles.
ConcludIng Remarks References The modIfIed AltItude WInd Tunnel deSIgn WIll prOVIde all the necessary faCIlIty capabIlItIes 1. AeronautIcs and Space EngIneerIng Board, Com- mIssIon on EngIneerIng and TechnIcal Systems, for conductIng propulSIon system IntegratIon and NatIonal Research CouncIl, "AeronautIcs Tech- adverse weather research. The capabIlItIes of the rehabllltated AWT relatIve to those needed for nology POSSIbIlItIes for 2000: Report of a propulSIon system IntegratIon research, are sum- Workshop," NatIonal Academy Press, WashIngton, marIzed In FIg. 24. ThIS faCIlIty would SImulate D.C., 1984.
both true altItude pressure ~nd temperature con- • currently over the flIght range of Interest. It 2. WhItfIeld, J.D., and HartIn, J.P., eds. "Aero- lS a wlnd tunnel confIguratIon and therefore would dynamIC TestIng - A Look at Future ReqUIre- provlde the proper flow fIeld over the entIre test ments," AIAA Paper 78-765, Apr. 1978.
artlcle. It has a large test sectIon (20 ft across parallel SIdes), whIch WIth the plenum evacuatIon 3. ExecutIve OffIce of the PreSIdent, OffIce of system to reduce wall Interference effects, WIll SCIence and Technology PolICY (OSTP), "Report of the AeronautIcal PolICY ReVIew CommIttee," permIt testIng of full sIze hardware IncludIng Nov. 9, 1983.
actual propulSIon systems along WIth a SIzeable portIon of the aIrcraft. It Includes an exhaust 4. Towne, C.E., Povlnelll, L.A., Kunlk, W.G., scoop to remove engIne waste products.
Muramoto, K.K., McClallln, K.L., Hughes, C.E.
The capabllltles of the rehabIlItated AWT rela- and Levy, R, "AnalytIcal ModelIng of CIrcuIt tlve to those needed for adverse weather research, AerodynamICs In the New NASA LeWIS AltItude WInd Tunnel," AIAA Paper 85-0380, Jan. 1985.
as Illustrated for ICIng research, are summarIzed In FIg. 25 and also In Ref. 6. As stated above, thIS faCIlIty would correctly SImulate both altI- tude pressure and temperature. The proposed AWT 5. Abbott, J.M., Dledrlch, J.H., Groeneweg, J.F., 6. Blaha, B., and Shaw, R.J., "The NASA Altltude Povlnelll, L.A., Reld, L., Relnmann, J.J., and Wlnd Tunnel: Its Role ln Advanced IClng Szuch, J.R •. "Analytlcal and Physlcal Modellng Research and Development," AIAA Paper 85-0090, Program for the NASA LeW1S Research Center's Jan. 1985.
Altltude Wlnd Tunnel (AWT)," AIAA Paper 85-0379, Jan. 1985.
'oJ;.--
.-
FUTURE OF AERONAUTICS
- MAJOR ADVANCEMENTS STILL ACHIEVABLE - SIGNIFICANT TECHNICAL CHALLENGES EXIST -..HNPRECEDENTED DEGREE OF INTEGRATION - INTERACTION OF PROPULSION SYSTEM COMPONENTS - EFFECTS OF INSTALLATION ON PROPULSION SYSTEM Figure 1.
..
FUTURE AERONAUTICAL SYSTEMS
Flgu re 2.
HIGH SPEED TURBOPROP PROPULSION C-84-1340 Figure 3.
C-84-1325 Figure 4.
C-84-1343 Figure 5 • . ADVANCING BLAOE CONCEPT (ABC) .
Figure 6.
PROPULS"fON SYSTEM INTEGRATION TEST REQUIREMENT
CONVENTIONAL FUTURE SYSTEMS TURBOFANS ~f---:--i
E ~-l= -B-]
~ MACH 04 TO 05 LINtrORM INFLOW UNCOUPLED FROM EXTERNAL
~ Eu ~-l Bjli-J
AIRSTREAM EXTERNAL FLOW SIMULATION AND FULL/LARGE SCALE Figure 7.
PROPULSION SYSTEM INTEGRATION TEST REQUIREMENT
SEA LEVEL TUNNELS • 3 TIMES FLIGHT DENSITY - EXCESSIVE BLADE AIR LOADS - 3 TIMES POWER • REDUCED FLUTIER SPEEDS ALTITUDE (KFT) 20 MACH NUMBER
I CORRECT AMBIENT PRESSURE I
Figure 8.
PROPULSION SYSTEM INTEGRATION TEST REQUIREMENT
UNREFRIGERATED TUNNEL STAGNATION 50 TEMPERATURE, 0
~3
'F -50
o 2 6
MACH NUMBER
..... -
113' TEMPERATURE DIFFERENCE RESULTS IN 10 TO 12% OVERSPEED TO MAINTAIN SIMILARITY MISMATCH BETWEEN ENGINE EXCITATIONS & BLADE NATURAL FREQUENCIES
ICORRECT AMBIENT TEMPERATURE I
Figure 9.
PROPULSION SYSTEM INTEGRATION TEST REQUIREMENTS
SUMMARY
• EXTERNAL FLOW SIMULATION • CORRECT PRESSURE AND TEMP~RATURE • FULL/LARGE SCALE SUITABLE FACILITY NON EXISTENT Figure 10.
ADVERSE WEATHER OPERATION
C-84-1413.
Figure 11.
ICING R&D APPLICATIONS
• PROPULSION SYSTEMS -INLETS - CARBURETORS -FAN - PROPELLERS fI FIXED AND ROTARY WING AIRCRAFT - ADVANCED AIRFOILS - HIGH LIFT DEVICES CD-SF Figure 12.
NEW D~VELOPMENTS IMPACTING FUTURE
ICING R&D
-ZERO BLEED ENGINES -COMPOSITE MATERIALS - ADVANCED AIRFOILS ...... HIGHLY INTEGRATED VEHICLE CONFIGURATIONS • ADVANCED AVIONICS/ELECTRONICS -NEW MISSION REQUIREMENTS Figure 13.
ICING R&D TEST REQUIREMENTS
• TYPES OF ICE GROWTH RIME,
~::::=:::::==
~---
DROPS FREEZE ON IMPACT DROPS DON'T FREEZE ON IMPACT • ICE GROWTH IS A FUNCTION OF • VELOCITY • AMBIENT TEMPERATURE • AMBIENT PRESSURE • LlOUID WATER CONTENT • WATER DROP SIZE • AIRFOIL SIZE. SHAPE • ANGLE·OF ATTACK IMANY COMPLEX VARIABLES CORRECTLY SIMULAJ1Q] Figure 14.
EFFECT Q.E SIZE OF OBJECT ON ICE ACCRETION
..sO 025 ft DIAMETER
o
1 ft "",- DIAMETER SIMPLE GEOMETRIC SCALING NOT CORRECT - VELOCITY, LIQUID WATER CONTENT, TIME OF ACCRETION, AND MEAN DROPLET SIZE MUST ALSO BE SCALED FIgure 15.
ICING R&D TEST REQUIREMENTS
50000 40000 TEST IN IRT FACILITY 30000 ALTITUDE, ft 20000 10000
o 2 4 6 10
MACH NUMBER
I EXISTING GROUND FACILITIES DO NOT SIMULATE FLIGHT CONDITIONS AND SCALE I
(D"'14~ Figure 16.
ICING R&D TEST REQUIREMENTS SUMMARY
• FLIGHT ALTITUDE SIMULATION • CORRECT FLIGHT SPEEDS • -CORRECT MOISTURE CONTENT AND FORM • FULl/LARGE SCALE SUITABLE FACILITY NON-EXISTENT or CD U I(JII~ Figure 17.
NEW TEST FACILITY REQUIREMENTS
• CONCURRENT PRESSURE AND TEMPERATURE SIMULATION OF ALTITUDE • LA8GE SCALE TEST ARTICLES • FULL SUBSONIC SPEED RANGE • WIND TUNNEL CONFIGURATION- AERODYNAMICS/ACOUSTICS • PROPULSION SYSTEM OPERATION/SIMULATION • ICING, HEAVY RAIN CAPABILITY
I NO EXISTING NOR PLANNED FACILITY MEETS THESE NEEDS I
Figure 18.
ALTITUDE WIND TUNNEL Figure 19.
ALTITUDE WIND TUNNEL
TEST SECTION CAPABILITIES
/-'" "T
MACH NUMBER o TO 0.9 + 20FT
ALTITUDE o TO 55 000 FT +
I * 1
",_/1tL
0 0 TOTAL TEMPERATURE -40 TO 60 F Figure 20.
- ..
STANDARD WIND TUNNEL COMPONENTS
.
TWO 30K HP .
~
DRIVE MOTORS ()c[cc~ 1-------'«0-rl+th+-~
..... -
TUNNEL HEAT EXCHANGER 20 ft dlam FLOW TEST SECTION CONDITIONERS Figure 21.
HEATED TURNING VANES PLENUM EVACUATION SYSTEM REMOVABLE WATER ENGINE EXHAUST SCOOP SPRAY SYSTEM Figure 22.
TEST SECTION FEATURES
• OCTAGONAL CROSS SECTION • SLOnED WALL WITH PLENUM • FLAT WINDOWS • FORCE BALANCE • REMOVABLE ACOUSTICAL WALLS • BOnOM MODEL ENTRY • RAPID MODEL ACCESS Figure 23.
AWT SATISFIES PROPULSION SYSTEM INTEGRATION
TEST REQUIREMENTS
CONCURRENT PRESSURE & TEMPERATURE 50000 100 40000 ALTITUDE. 30000 STAGNATION " 20000 TEMPE~ATURE 0 ....
l-f- -\-- -<-- f- i:~ <w.,,_ \- i- ....-"
HI
(DUI .. H Figure 24.
>4-
A WT SATISFIES ICING TEST REQUIREMENTS
AWT 20 II TEST SECTION TEST IN IRT FACILITY 50000 40000 • CORRECT FLIGHT SPEEDS • LARGE SIZE ALTITUDE, 30 000 ft 20000 10 000 1 a a 2 4 6 8 MACH NUMBER Figure 25.
2 Government Accession No 3 Recipient's Catalog No
1 Report No NASA TM-86921
AlAA-85-0314
4 Title and Subtitle 5 Report Date
The Altitude Wi nd Tunnel (AHT) - A Uni que Fad 1i ty
6 Performing Organization Code
for Propulsion System and Adverse Weather Testing
505-40-74
7 AuthOr(s) 8 Performing Organization Report No
E-2415
Roger Chamberlin
10 Work Unit No 9 Performing Organization Name and Address 11 Contract or Grant No
National Aeronautics am! Space Administration
Lewls Research Center
13 Type of Report and Period Covered
Cleveland, Ohio 44135
12 Sponsoring Agency Name and Address
Technical Memorandum
Natlonal Aeronautics and Space Administration 14 Sponsoring Agency Code
Washlngton, D.C. 20546
15 SJPplementary Notes
Prepared for the Twenty-third Aerospace Sciences Meetlng sponsored by the
Arnencan Instltute of Aeronautics and Astronautics, Reno, Nevada, January 14-17, 1985.
16 A~stract
A need has arlsen for a new wind tunnel facillty wlth unique capabillties for
testlng propulsion systems and for conducting research in adverse weather condi-
tlons. New propulslon system concepts, new alrcraft conflguratlons with an
unprecedented degree of propulsion system/alrcraft lntegration, and requirements
for alrcraft operation in adverse weather dlctate the need for a new test
faclllty. Requlred capabilities include simulation of both altitude pressure
and temperature, large Slze, full subsonic speed range, propulslon system opera-
tlon, and weather simulation (i.e., iClng, heavy rain). A cost effectlve
rehabll1tatlon of the NASA Lewis Research Center's Altitude Wind Tunnel (AWT)
wlll provlde a facility with all these capabi11ties.
17 Key Words (Suggested by Author(s)) lB Distribution Statement
Unclassified - unllmited
Wind tunnels; Propulsion; Propulsion
STAR Category 09
system integration testing; Adverse
wea ther testi ng
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