ACR No. E5E19

NATIONAL ADVISORY TTEiE FOR AERONAUTICS

ORIGINALLY ISSUED

June 1945 asAdvance Confidential Report E’5E19

THE EFFECT OF INLET PRESSURE AND TEMPERATURE ON THE

EFFICIENCY OF A SINGLE -STAGE IMPULSE TURBINE HAVING

AN 11. O-INCH PITCH-Ii(NE DIAMETER WHEEL

By David S. Gabriel, L. Robert Carmanand Elmer E. Trautwein

Aircraft Engine Research LaboratoryCleveland, Ohio

NACA. . . . ...

.,.

WASHINGTON

NACA WARTIME REPORTS are reprints of papers originally issued to provide rapid distribution ofadvance research results to an authorized group requiring them for the war effort. They were pre-viously held under a security status but are now unclassified. Some of these reports were not tech-nically edited. All have been reproduced without change in order to expedite general distribution.

E-218

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EffIolency tests have been mnducted on a single-s~ impulset&bhe haYiw, an 11~0-inch pitch-line diamter wheel with insertedbuckets and.a fabricated nozzle diaphragm The tests were made todetermine the effect of inlet pressure, Inlet tempemture, speed, “and pressure ratio on the turbine efflclen~. An anal.yEl10lapresented that rela~es the effeot of Inlet pressure and tempemtureto the Reynolds number of the flow. The agreemnt between theanalysis and the experimental data Indhxxtes that the changes inturbine efficiency with Inlet pressure and temperature ?my beprincipally a Reynolds nuuibereffeot.

ImRoDucTIoIv

The efficlenq of turbines is conventionally~preeented as afunction of the blade-to-jet speed mtlo.@ the pressure ~tio.Sam @ataare available in the literature.on the effect of thesev&riablm on turbine perfomanoe. It has been”~mlly assured.that the effects on perfomanos of,inlet pressure and temperaturefor 8 given blade-to-$et speed mtio and pressure mtio are small.No data on these effects could be found.

Adequate test facilities are not always available for testingturblnqs under aotual operating .ponditionsand exper-nters often.teat at the proper blade-to-jet,speed ratios and.pressure ratios .but at Inlet temperatures and pressures that differfrom aotu@Oyeratlng conditions● Because * the.need for Info-tiqn on theeffects of Inlet temperature and pressure in addition to the effectsof blade-to-jet speed rat10 and preesure ratio, the XVACAClevelandbborato~ conducted tests frcnnJuly to October 1944 cm an exhaust-@e turbine using both hot gases qnd alr aa the driving flulds.These tests oover a mnge of inlet preseures frcau10 to 60 inches

I

2 Em19

.

of mm?o~ absolute, Inlet temperature~ from 550° to 2000° F absolute,and prOSOUZ’0ratios from 1.4 to 5.2. A ~thod of oo~~tion of ~data is pres6ntB& in”this report.

An attempt 1s also made to oorrelate the effeote of Inlet pres-sure and temperature by Introducing the Reynolds number. An analyalathat shows the relation of the inlet pressure and tempmature to theRe~olds nuniberis presented.

APPARATUB. . .

A single-stage impulse turbine having an 11.0-inoh pltoh-linediameter wheel with inserted buckets and a fabrloated nozzle diaphmagmwas tested. Bucket-to-nozzle clearanoe was set at O.I-38InOh. A high”speed hydraullo dynamometer was ooupled to the shaft to absorb theturbine power. The general wrangement of the experimental test setupand the piping system Inoludlng the hot-gas produoer is shown In fig-U1’OS 1 and 2.

The tuz%ine was driven by air at 550° F absolute and hot gasesat various Inlet temperatures and pressures. An A.S.M.E. orlfioeinstalled in the oombustlon-air piphg ahead of the hot-gas producerwas used tm msasure the air flow. The gas temperature at the nozzle-box Inlet was meaeumd with a quadruple-shielded chroml-alumelthermmouple and a self-balancingpotentIometer. This te~raturewas taken to bs the total temperature at the nozzle-box Inlet. Thestatic pressure at the nozzle-box inlet was measured in a manifoldoonnected to four pressure taps In the _ oross section of theinlet pipe.

The driving fluid was disohsrged from the turbine into aplenum ohauiber,whioh was direotly oonneoted to an altitude-exhaustsystem. The static pressure in the plenum ohauiberwas taken as thebuoket disohar~ pressure pd. The static-pressure tap for meas-

uring the dlmharge pressure was looated shout 1/2 Inohbehind theetiernal oooling oap, as shown by the detailed slmtoh in figure 3.The”end of tie pressure-tap tube was plugged and a hole was drilledabout 1/4 In& .frcmthe end of the tube on the downstream side. Allpressures were measured with mercury manometers. The looatlon ofthe points where temperature and pressure moasurements were tie isshown In figure 3.

Iaakage of alr between the atmosphere and the turbtne was pw -vented by a housing around the turbine-bearing assemiblyad by plugswelded into the openh& In the annular support between the nozzlebox and the nozzle-box baffle. A lab~inth seal g- was Instqlledaround the turbine shaft between the h~using and a pressure-balancing

.

.

Ohadber;&Ihh-OOUld be evaouated by a Jet p= or pressurized byoompreaeed air. Leqlnigeof air between the ohamber and the housingwas prevented by adjusting”the preamre In the pressure-balanolngohaniberuntil a mancmeter oonneoted to the two spaoes between therings of the lab~inth seal gl@ showed zero pressure drop.Coon@ oapq plaoed In dose proximity to both sides of the turbinewhoela@ oooled by~ter ~vlded some cooling of ~ wheel andthe bearl~ hOUSi~. . -

. . .“

~ter-to~ue m&nmements were nade with “anHACA M&wed.dlax torque Indioator (referenoe 1), The turbine speed wasmeasuredwith a standardenginetachometer. The taohcmeter wasfitted wl~ an enlarged Indloatlng dial hating very fine ~ivisionato Inorease the”aoou~oy and the 6aBe”of &eadlng the lnsttint.Two taoljmeter genemxtora were.used to oover the range of turbine8peet@ In this test. One of the generators turned at the samespeed as the turbine tachometer @lve and the other turped at twloethe speed. The higher-speed genemtor was used at the low turbinespeeds for greater aomaraoy of speed measummen t. “

The nozzle box was Insulated for the final series of tests.The insulation used was an asbestos base mterial, whloh was plaa-tered direotly on the nozzle box with a thickhess from 1 to 2 Inohes.

A oross sootlon of the hot-gas prqduoer is shuwn In figure 4.Air passes through the orifioe, enters the producer near the top,and flows dowmward through the annular spaoe between the inner andthe outer shells to provide oooling for the shells. The air Isturned through an aro of 180° at the bottom of the produoer, wherethe flow Is divided between the epaoe provided for the lgnlter-nozzle assemblies and the two vaped seotlons.

The produoer has eight Igniter-nozzleassenibliesand oan beopemted with any number & the igniter-nozzleassenibllesIn.use.

“Eaoh Igniter assembly has h fuel-spiny nozzle with a “double-electrodeIgnlt?r, whioh furnlahee oontinuotisIgnitloh. The fuel flow to thenozzles is Sndlvldwlly controlled by needle valves In the lines tothe fuel “nozzles. The tempemture of the gas la varied by using adifferent size or amber of nozzlm. Small adJustinents”of tempera-ture ere made by throttling the fuel llnee ti ohhnge the fuel pres-sure at the .-” nozzles. The fuel flow is nmasured with a cali-brated rotsmeter.

The air is heated by burning gaeoliti, whloh 1s In$eated throughthe fuel nozzles. Ho fuel was burned for ,W tests at 550° P abso-lute. The gases flow frau the produoer to the turbine nozzle boxthrough a ptpe a~~tely 23 feet long apd “insulatedwith a 3-inohthiolmess of mixed asbestos“fiber a@ milled slll~ hel~ ti plaoe by:.

HIIm ■ —mn81m. mm ,,-—--,. .,

4 EAC4 AoR X!Jo.E5E19

a lazyym duet that enoloaes the pipe oonveylng t+e hot gaaea. Adia@xuu of the inlet ~tpe is shown in f@ure 4. The pipe ~iaYu:eteti’ohanges from 10 to 6 Inohes before it is mnneoted to the .turbine’nozzle box, .

Before the tufilne was ln&alled, temperature and total- ~pressure sumeys were made in the piping system at a point apprm.”hmtely 8 Inohes upstream from the flange to whloh the nozzle boxwas attaohed. Tmverees were mule aoross 2 diameters of the 6-lnohpipe at right angles to eaoh other. At a gaa temperature of 1400° F,a variation of 10° 1’was found. Total-pressure surveys were made atdifYerent gas tempemtume for a.,weigbtfluw of approx-tely2.2 pounds per second. There Was no variation In total pressurewithin a 5-inoh-diamter c3role with its oenter line on the centerline”of the 6-inoh pi~. At points 1/4 lnoh from the pipe wall, thetotal pressure was found to be approximately 75 peroent of the totalpressure”“iimsuredIn the oenter of the pipe. l!hbsetests tndioatedthat the velooity and the tenrperatureprofiles aoross the pipe werevery uniform

Although these surveys were made with Impaot tubes, the totalpressure at the inlet to the turbine for the test data was oomputedby adding the measured static pressure at the nozzle-box inlet tothe average velooity pressure oomputed from the mntlnulty equation.The use of the oontlnuity equation waa justified by the existenoeof the flat velooity and temperature profiles.

the”

The outside wheel diameter waa measuredteats. llomasurable ehmtohing of theend of the tests.

at intervals throughoutwheel was observed at

AC@RACY

The mdhod auggeti by the A.S.M.E. for estimating the acmrmyof ms urement of air flow utilizing their orlfloe data gives a prob-able error “of+1.17 peroent. Turblfi+ihaft torque was meaaured tothe nearest o ●15 foot-pound● The taa?xmeters were oallbrated and thered.ings taken in the tests were correoted by use of the calibrationourre.’””The ttiine -speed measurements were amumte to MS rpn forspeeds f- o to 17,000 rpn and +30 rpm dor Smods ~~ 17~0~0 to “21,000 rpn. All ptiaku’ereadingswere taken to 0.05 Inoh of merc~;

.-.. .“

Efftolenoy teats were tie over a range of inlet temperatu=sand pressures and preaaure ratios, The followi~ table ShOWS the .

approximate teat oonditiohs:. .

IVACAACR HO. E5E19 5

Pre8eure rat10 Total inlet Total inlet- ‘-PlyPd-’ preseure “ - “tsmperattie.

Pi Ti(in, Eg aba.) (~ ab~.)

Tests with uninsulated nozzle bor; speed range,3000 to 21.000 mm

1.4, 2.2, 3.0, 3.9, 5.2

1.4, 2.2, 3.0

1.4: 2 2, 3.0

27

10192735 “435260

27

5501200 “1800

.1200

16002000

Tests with uninsulated nozzle box; constant blade-to-jet speed ratio, 0.4

2.2 52 100035 2000

14001800

Tests with Insulated nozzle box; speed range 3000

.WY=+ ii

I 16001800

SYMBOLS

Ad annular area swept by turbine budcets (sq ft)

6“2

acceleration due to gravi~y””32.2-(ft)/(see) or dksionalmnstant, 32.2 (lb)/(slug\

% mass flow of air (slugs)/(see)

..

#,.—

-. —..I

mass flow of air plus

turbine speed (rpm)

. . NACA AcR no. B5E19

fuel (slugs)/(@c)

statlo presbure of turbine dlsoharge at plenum chamber(In. Hg absolute)

total pressure at nozzle-box inlet (in. Hg absolute)

turbine shaft power (ft-lb)/(see)

thebretioal turbine power available for expansiontotal temperature and pressure to outlet static(ft-lb)/(see)

gas oonstant for air, 53.35 (ft-lb)/(lb-%)

from Inletpressure

gas oonstant for oumbustion produots (ft-lb)/(lb-%)

Reynolds number

gas temperature (°F absolute)

total temperature at nozzle-box Inlet (% absolute)

blade p?.tch-linespeed (fps)

theoretical jet speed (fpe)

average axial oomponent of turbins discharge veloolty (fps)

ratio of specific heat at constant pressure to speoiflo heatat oonstant volume

turbine effloienoy definedical power mmputed from

turbine Inlet and statlo

as ratio of shaft power to theoret-total tempemture and pressure Rtpressure at the turbine dlsoharge

1.1value of q at standard value of pi/Tl

( )0.009in. Hg/(°Fabsolute)l:l

turbine effiolency defined as ratio of shaft power to &Lf-ferenoe between theoretical power and kinetic power mrre-sponding to average axial ccnnponentof veloclty at tur-bine disoharge

visooslty of ccmbustlonproduots (lb-see)/(sqft)

.

‘ MEJ!EoDaB’AnKLYsIs

7

-. .. . . . . . .The turbln& eff~olen& for the tests mpofied herein was oalou-

lated aooording“tothe methods of references 2 and 3.- The oaloula-tlons of air flow were made aooofiing.to the standard praotke of

.the A.S.M.E. .

.The effioienoy of a gas tm%ine of the oopetapt-preaauretype1s assum~ to be a funotlon of the blade-to-$et-speed ratio, thepressure..mtio, and the ~ypolda n@er. Other variables, suoh asleakage,.windage, heat losses, and bearing frlotion, “~ assuwd to “be of seoopdary lmportanoe or dependent cinlb prlnolp@l variables.TMs statemept may be written In h following equation:

H the dsswgption Is tie that visoosity is proportional~, where n Is a oonstant, the theorettoal Reynolds number.ooimspondhg to the theoretloal Jet veloolty v is given by

~ (1)

to

J.*%+%?-](z)

where Kl is a constant depending on the visooslty of the fluid,

p is.the theoretloal density corresponding to the theoretloal Jet.velooity,and L Is a oharacteristlcdlmenslon of the turbine.For a given turbine, L Is oonstant. If the variations of y and

%) are

turbine

negleoted, the Reynolds number (equation (2)) for a given

and fluid beooaws .

Inasmuoh 80 the ratioequation (1), the only

Pi/Pal*9 a~eadY listid as a variable innew variable added by the Reynolds number

“. . ..

is the ratio ~ Pi/TI()“n+~2 , Equatlod (1) my then be written

[

b 1(Jn+~~uf (4)“u/v,P1/P~J pi i

11 Im—m —11 Illm-—m , 1, ,.- ,. . .—

.

Although the Reynolds nyuibercorresponding to lsentmplo flow was

()n+p‘ used”to estciblishthe factor pi/Ti , the Reynolds number

of the flow over the buoketa ohange on4 by funotions of pi/pal

and u/v and thus introduoe no new ~iables.

h logaritlmio plot (fig. 5) of visoosity of air againat theabsolute tempemture reveals that for the range of temperatures“from 1000o to”20000F absolute there is very little variation f’rcnua straight line with a slope of approximately 0.6. The slope of

.t)iecuYve for luuer temperatures 1s sllghtly greater. The data forthis ourve were taken from reference 4. The composition of theworking fluld during the tests varied negligibly from that of air..Equation (4) then reduces to: .

(5)

The verlablee Sor oorrelatlng the mss-flow data of the tur-bine are revealed by d obneideratlon of the equation for mass flowthrough either an ideal or a convergent nozzle; both show the samevariables. @ =ss flow through an Ideal nozzle of area ~A“ forexample, 18 given”by . .

where ~ “is the theoretical density at the nozzle exit and v Isthe theoretloal velocity at the nozzle exit. This relation reveals

%that the quantity — /%~ is a function of pal/pi. _ eq~tlonPI

for mass flow througha shuple converging nozzle in the supersonic

%range Indloates that in this range —

Pi $== ‘1 Is a constant. The

presenoe of the turbine wheel Introduces some interference with theflow frcm the nozzle-. It Is reasonehle to expect that the amountof interference depends on the blade-to-jet speed ratio. The theo-retical jet speed is giyep b

.v=/2:%T,[l-&)~] (7)

.

NAOA AcR Ho. E5E19

The blade spqed u for aYven tudbine is

turbine speed H. The rat~o ,U,V Is *refore,. ..-

9

proportionalto theproportional to

,..

@W, ~ f(P,/P& The ratlo pi/pal has already b6en listed as

o“m of.the variables for plotting the ~ss-f low faotor; thus the.only additional variable Indicated by this discussion Is @~ N.The ~ntattve correlation of the maqs-flow data can be made by plot-

REsmm

Figures 6 to 8 are conventional curves of the tutilne efficiencyq plotted against the blade-to-Jet speed ratio. They show theeffect of the nozzle-box inlet pressure and temperature and the pres-sure ratio on the tudbine.efflcienoy. These curves are all substan-tially parabolio with maximum efficiency occurring at a blade-to-Jetspeed mt 10 of approximately 0.4. The effioienoy for a normal oper-ating condition of the turbine In a turbosupercharger (Inlet pres-sure, approxhtely 27 h. Hg absolute; inlet tempemture, 1600° E’absolute; blade-to-Jet speed ratio, O.4; and pressure ratio, 2.2) IS59 percent.

Cross plots showing the variation of turbine efflolenoy at aconstant blade-to-jet speed ratio (O.4) with the three variables arepresented In fIgure 9. The general trend of the effictency varla-tion is more easily visualized from these curves than from those Infigures 6 to 8. Figure 9(a) shows that mximum efficiency oocurs ata pressure ratio of approximately 3 and figure 9(b) shows that effi-ciency decreases as nozzle-box inlet temperature Increases. Theincrease in effloiency with nozzle-box Inlet pressure is presentedIn figure 9(0). Plotsof the cmrves of figures 9(b) and 9(0)onlo@arithmlc paper Indloate @at the eff$oienoj varies with the Inlettemperature to the -0.075 power and with the Inlet pressure to the”0.067 power over the -e of tests. The ratio of these eXpOmntSis 1.12.

It has been shwn in the mthod of analysis that, for constantpressure ratios and b~de-to-Jet speed ratios, the turbine efficiencyis a function of the mtlo of noz~le-box inlet pressure to the1.1 power of * Inlet temperature. Plots.& the turbine efflcienoy

1.1~inst the faotor P@~. are e.hiiwn In figure 10.. Curves are

shown f-orvariable pressure mtio at eeveml constant blade-to-Jetspeed ratios. Very”good correlation Is noted in the data for thelnlet~tempemture range shown (1200° to 2000° F absolute) and forinlet presmres from 10 to 60 inches of mermry absplute. -The setof points oorrespmdlng to the air tests with w inlet temperature .

10 W2AACRN0. E5U9

of 550° F absolute are slightly dieplaoed from the falred ourvm;

the ms@tude of the displacement doeB not exoeed 2~pemmnt Iri

efficiency (f’ig.10). This dlsplaoement my be &used by the ohangingelope of the vlsooelty curve at temperatures less than 1000° F abso-

.“1.1lute; The good’correlation obtained with the faotor pi/Ti lndi-

oates thqt the ohange of turbine effiolenoy with nozzle-box inlette~rature and pressure for oonstant pressure ratio and blade-to-Jetepeed ratio may be a Reynolds number effect. Further Investigationis required, however, to establish this facb oonoluslvely beoause ofthe small ohanges in efficiency Involved.

The pmallelism of the mrves of oonstant pressure mtio at agiven value $& blade~t~-jet speed ratio u/v in figure 10 suggestedthe following prooedure for condenetng the presentation of the tur-bine effiolency: F&any given pressurO ratio the quantity qs 18

defined as the value”of the turbine effiolency at a value of

1“1 of 0.009 kohmeroury pm (% abeolute)l’l,Pt/Ti These Walues

of.qs are shown in figure n(a) plotted against u/v for various

The Valuss of1.1

value of pi/Ti

value of u/v and

mrlous values of

and pi/Til’l the

turbine effiolenoy for other than the atandazxl

are divided by the value of q= for the same

@d and are plotted against- pi/Til”Z for

U/V in fi@rs n’(b). For a given value of u/v

value of ~/~s Is nearly independent of pi/pal.

This sort of plot Is an expedient that works fairly well In the “present,oase but oannot be’generally recommended. The nmre hcoumteand fundamentally mone Bound presentation Is that of figure 10. “ Inother types of turbine, the correlatiti”of figure 10 w not.holdinasmuoh”as there Is no assuranoe that Reynolds number will affeota turbine of different design in the sam manner or that othdr fao-tora not involving the Reynolds number will not oause some variation.

The acouraoy of the correlation varies somewhat with the oper~atlng conditions. Figure 12 shows an example of acurve OdOulddfrom figure 11 and an experimental ourve. The slight soatter shownIs typloal of t4e maxlmumvariation to be expected, approximately*1 peroent in effioienoy, over the tempemture range from 1200° to20000 F,absolyte. The data at 550° Fabsolute show”a somewhat

larger soatter; the -imum scatter of approxW3tely 2~peroent in

effloienoy oocurred at pressure ratios less than 2.

1“

Figure U Is a plot of the gas-flow faotor~@%-

Tf a@nst

tti press&e ratio-e&! the prd”ibt’of “thetudblne speed ad the-.square root of the ~atlo of HACA standard sea-level temperature to.the nozkle-bo~ inlet.tlnnperature. This ratio 1s proportional tothe blade-to-jet spedd ratio for a oons~t pressure ratio. momfIgure I.S(a),tbe *F flqw ~ be oo~l@ed within H.5 peroentfor t@d range of tept.valuea @ pl and for a range of Ti frinn

1200° to,2.000°3‘absolute.lBeoause the iata & an inlet tempezll-ture.of.:550°~.absolutedid not fall pn the.same”curve,.an addi- -tlonal chart (.flff.13(P)).is aboyn for these data. . Cross plots.of.figures 13(a) sad 13(b) are shown tn %igures 13(o) and’13(d),..Witifigures 11 and U, and ret’emenoe3, the turbine power.for any oondl-tlon covered by the reported tests”=Y be uloulated.

..

The xmsults of tests with the nozzle box Insu&ted & bomparedwith tests tn whloh the nozzle box was not.$nsulated in fIgure 14.No air kas blown over the nozzle box in the urdnsulated tests. Itis evident from figure 14 @at the dlfPerbnoe In perfo~ oausedby the Insulkthn was small and within the nmgnitude of experlnientalerror. Although the curves are given only for a pressure ratio of2.2, data on other pressure ratios show similar results. It my bemnoluded. that, for inlet-@s tempemtures from 1200° to 1800° F .absolute, the differeno.esIn”effioiexaoyfor the oases of Insulatedand uninsulated nozzle box are negll@ble when the alr external tothe nozzle box Is quiet.

“Theturbine effloienoy as previously defined gives the shaft‘workas a ratio of the theoretloal work for an expansion fr~ thetotal pressure at the turbine Inlet to the statio pressure at thetuti@e outlet. This efficlenoy Inoludes Zn the theoretl~l poweravail.ab~ s- ener~ that may be utilized for jet propulsion orIn su@eedlng turbine stages. h applioatiom where the turMne-dlsohar~ velocity Is utlllzed for Jet propulsion, it Is appro-priate *O define an efflclenoy in whloh the turbine is oredl.tedforthe Hnetio energy of the disoharge Jet. A mmiber of deflnltlonsof this effloienoy sre possible. In the ohoioe of a definition,oonsidemation should be given to the ease of measurement and oompu-tatlon aqd to thb praotloal aspeot of the portion of the discvelooity remverable for Jet propulsion. In the present .repwt.-turbine effloiemy under discussion is def3ned as . “i

(8). .. .

The value of Va is equal to”the mass flow of gae d$vided by.the ‘

buoket annular area Ad and the gas deqsity at the buoket exit and

1 .--.-

Illmlm 11 ,,

12 EACA m no. E5E1.9

..

16 given by:t@” equation

It is’apparmit that the tuz%lne la credited in equation (8) .with the kinetio energy o“orrespondhg to the energy of the axialoomponeti of this aVez~e dimharge veloaity. Theoretically, thetota~;dlscharge velooity @m poeslbly be utilized for Jet propul-SiOn “bymdans”of properly”shaped guide ~“s. Beoause of theohE@l@ angle of “athaokat the guide“varieswith ohanglng operatlkg

- oonditionstimt of vanes‘thatmE& be good”for one oondltionmay .be poorat othdrs;”furthemore,beoausethe total”velocity varieswith radial and angular poaltlon, a survey would be requiredforitB de’termination’..The average axialvelooity va, on the other

H&d, oan b~ o&puted: from the ~asured mass flow of gas and thearea:swept By”the bUdsets. It 16 evident that the proposed defi-“tii”ti~of turbi~ efficie~y la not without obJection but it does“ have the advantage “thatit pay be readily oaloulated.. .

m Figurd 15.shDws a plot of “qt/ where q’ was calculated?by $%. twbin?-efficiehoy equation 8). The values of ql range

frorh~bout 5 to, 22 peroent higher than the corresponding valuesof “q;””~emtio ~1/q is higher for higher pressure ratios andlower blade-to-set speed ratios. All the data over the range oftemperatures from 120@ to 2000° F absolute and Inlet pressuresfrom 113:3to 53.7 inches of mercury absolute are correlated on thisourve”wlth”ah aoouraoy of *1 percent. For any given value of pres-sure mitio.and blade-to-jet speed ratio the quantityto be independent of Inlet temperature and pressure.urea 11 and 15, the efficdenoy T’ may be oaloulatedtion within this range.

S12WlRYm Rl!SuLlT8..

q’/q iO seenFrom flg-for any mndi-

I!5’flclencytests on a single-stage impulse turbine having an11.O-inoh pitoh-line diameter wheel with Inserted buokets and afabricated nozzle dfaphm~ over a mnge of Inlet pressurws fz%nu10to 60 Inches of meroury absolute and Inlet temperatures frcm 1000° to20000 F absolute have Indioated the folluwi~ results:

1. The efficiency for a nomml operating oonditlon (Inlet pres-sure, approximately 27 in. Hg absolute; inlet temperature, 1600° Fabsolute; blade-to-jet speed ratio, 0.4; and pressure ratio, 2.2)was 59 percent.

*.

.

IWCAACRNO. E5E19

2. The ohange in turbine efflclenoy forand blade-to-jet-speedratio over a mnge of’

pressures .wnEIcorrelated &dz& the f~otor

derived from the Reynolds number equatton

where ..

Pi . total inlet pressure (in.Hg absolute)

Ti total Inlet temperature (% absolute). . .

1.3

oonstant pressure ratioInlet tempemtures and

1.1PI/TI ~ whloh W8S

. .

This result hdioates that the variation in”turbine effl@enoy withinlet oondltions for a oonstant pressure. mtilo and blade-to-Jetspeed ratio ~ be prlnolpally a Reynoldsnumbereffeot.

3. The”air flow oould be oorrekted with an acxnn’aoyof*1,5 peroent over the range of inlet tempaatures from 1200° to2000°1’ absolute and total inlet pressures from 10 to 60 Inohee of

% ~~ against the pressure ratiomero~ absolute by plotting —Pi!@b i

and blade-to-Jet speed ratio

where

% mass flow ofair plus fuel (slugs)/(see)

~ gasoonstant for combustion products (ft-lb)/(lb-°F)

4. Over the range of inlet gas temperatures frcxn1200° to1600° R’ absolute, Insulating the nozzle box oaused no ohange in theturbine effioienoy, as oompared with tests of an uninsulated nozzlebox in whioh the external air was quiet.

5. - tie amputation of turbine effioienoy when the tudbineis oredited with the kinetlo energy corresponding to the averageaxial cmuponent of the velooity behind the turbine buokets, aninorease in efficiency betweep 5 and 22 peroent for pressure ratiosbetween 1.4 and 5.2 and b~e-to-Jet speed matlos betw6en 0.1 and0,6 was obt~ined, In general, the larger dunges in effloienoyocourred at the snmller blade-to-Jet speed ratios and the largerpressure ratios. . .

Airomft Engine Ileseeuwhmborato~,Rational Advisory Comittee for Aeronauticsj

Clev51and, Ohio.

.

.,. ,.--.. ,-— .. ,—. . .. . ,. .. , .. —-,-. .. .. .. —..

REmamcl!a

HAOA Am Ho. E5E19

1. Moore, Charles S., Blermnn, Arnold E., and VOS13,Fred: !lheHAC4 Balanoed-Diaphragm ~ter-korque Indloatori KACARB ~0. 4C28, 1944.

2. Oabrlel, David S., and Carman, L. Robertt Effioienoy Tests ofa Single-stage Impulse Turbine Having an 11.0 -Inoh Pitoh-LineDiamter Wheel with Air as the Driving Fluid. NACA AOR No. E5030,1945.

3. Plnkel, BenJamIn, and Turner, L. Riohard: Thermodynamic Datafor the Computation of the Performance of Exhaust-Gas Turbines.NA@i~ NO. 4B25, 1944,

4. Boelter, L. M. K., and Sharp, W. H.: An Investigation of’AiroraftHeaterO. XVI - Determination of the ViBCOSity of ExhauBt Gaaesfrmu a Gasoline Engine. m~~O. 4F24, 1944.

HACA ACR MOO E5E19

L

Fig. I

---------

-.

-. I—Air-metering orifice

NAVIWU mvlsmyCOANITTEC FOR AERoNAUTICS

Figure 1..

- Schematic diagram of test setup showing hot-gasProducer.

Fig..2,: HACA ACR WOO E5E19

Figure 2. - Phorogroph of test apparatus showfng turbine onddynamometer arrangement.

NACA ACR Noo E5E19 Fig. 3

Inlettemperature, r\”.—

Nozzle-box inletpressure

\

L

–~

To exhausr

v

D—x

-rO exhaust

.—

—.

Discharge

9

Hlpr8ssure, Pd x ‘

Cooiing caps c

I

1 nozzle-boxboffie7

,,.

1S88 detail A

1-

1Pressure-

L

balancingchamber

Labyrinthseai giand

IATIONAL ADVISORYTTEE FOR AERONAUTICS

Figure 3. - Schemotic diogrom shouing the turbine housingand the location of the uorious points where measurementswere mode.

I

t-20’-OU approx.

NACA ACR. NO.” E5EI.9

\

—Nozzle box

I \

*

Igniter-nozzle

assenbl Ies

Inlet-pipe detail Hot-gas producer.

NATIONAL ADVISORYCOWITTEE FOR AERONAUTICS

Figure 4. - Inlet system.

-A,,1,

\.*/’

I

NACA ACR No. E5E19 Fig. 5

,.

NATIONAL AOVISORYCtilTTEE FOR AERONMTICS

0

6

/‘

Slopes 0.6. - -2

1200 300 500 1000 2000 4000

Temperature, Tl, ‘F abs.

Figure 5.- Variation of the viscosity of air with temperature.

NACA ACR MO. E5E19Fig. 6

.7

.6

.5

.4

.3

.2

NATIONAL ADVISORYCOWITTEE FOR AERONAUTICS x Pi/P& Pi

E — (in. Hg abs.

o 1.4 27.02.2 27.23.0

i 5.4 !::3.9

y, ‘\ u

//

o

(a) Inlet temperature, 550° F absolute.

=---l Pi/P* Pi

.6 / 0’5

\ (in. Hg abs.

/ L& e - ‘yL

\Xh o 1.4 20.5

rq ~ ~’ ---- *

\; 2.2 26.8

3.0 26.8

$ .5 - /2 ‘+ 26.8: %:\ 26.8

z /~..,

stJ \

k*a!

i

!x

.3 ,

/

1+

(b) Inlet temperature, 1200° F absolute.

Pi/P*x J’i

.6 n (in. Hg abs./+- —+,

+ 26.5: ;:;26.S

x 26.I3

.5 . Y iY---+ ~ ~ ~:: 26.826.8

1 \/

.4 .L

/$

\

/b

.3

[dr$

.20 .1 .2 .3 .4 .b .6 .7 .8

Blade-to-jet sped ratio, u/v

(c) Inlet temperature. lSOOO F absolute.

Figure 6.- Variation of turbine efficiency with blade-to-jet Spd ratio for ViWiC4iS pressure

rati09.

IIACA ACR No. E5E19 Fig. 7

F

.6

.5

.4

.3

,NATIONAL MVISORY Pi

COMIITTCE FOR aEROMAU71CS ‘i(% abs. ) (in. I@ abs. )

/ f q \o 34EI 27.0+ 1800 26.5

1y x 1600 26.5M31M 26.5

-$_ 26.5( ? \

I I I I

/~

L /~i

w

i

0’ u

d

(a) Pressure ratio, 1.4.

.6 (% abs. ) (b. Hg abs. )

+ 1200 26.8

.5

.4

.3

(b) Pressure ratio, 2.2.

Ti Pi

.7 (% abs. ) (in. Hg abs. )

2’7.3? 1:% 26.8x MOO 26.0

r$J ;~ 26.S

.6 26.8

.5

.4

.3

0 .1 ●2 .3 .4 *5 .6 .7 .sBlade-to-jet speed ratio. u\v

(c) Preqsure ratio, 3.0.

Figure 7.- Variatian of turbine ●fficiency with blade-twJet SPaed ratio for ~ari~a Mettemperature.

, ,, .,, ,, ,,,, .,.-. .,,-. .- . .

. ----- —....—.....— — ..— —— — ——..—.-

Fig.

.6

.s

.4

.3

8 HACA ACR MOO ESNATl~M. MV160RY

I I I I I Pi

EROMAUTICS (in. IW abs. )

.6

.3

I (a) Pressure ratio, 1.4.

I I IllI I I I I I I I&-kd I I I I

#

pi(in. Hg abs. )

o 18.5+ 26.8

35.1; 43.30 51.5

59.7

I 1

\A

w A

(b) Pressure ratio, 2.2.

.7Pi

(in. Hg abs.)

o 10.3

.6

v 59.7

.5

.4

.3

/

a

v lijii6ii7i]ilo .1 .$? 3 .4 ●

Bl~de-to-jet speed ratio, u/v● . .

(c) Pressure ratio, 3.0.

Flgvme s.- Variation of turbine efficiency with blade-to-jet speed ratio for various inlet~essures. Inlet temperatatre, 1200° F abSOlute.

ACR MO- E5E19 Fig. ‘9NATIONAL AOVISORY

CMITTEE FOR MRONAUTICS

“*7Ti

.6550

v -

.5.s00

Wessure ratio, pi/pal5

I (a) Efticieficy variation with pressure ratio. Inlet total pressure, 27inches mercury absolute (approximate).

W“v.i;* 6

dcJ

g .5 :

1[.4

400 800 1200 16fxl 2M0Inlet temperature, Ti, OF absolute

I (b) Efficiency variation with inlet temperature. Inlet total pressure, 27inches mercury absolute (approximate).

.

.

. ~ — — — — — — — — . — — - — — — — — — —

.4

.s--1o ao so 40 50 60

Inlet total pressure, pi, in. ~ absclute

(C) Uficiency variation wl”th inlet total pressure. Inlet temperature,12000 F absolute.

Figure %- Variation of turbine efficiency with praseure ratio, inlet temperature, anclinlet total preesure. 21ada-to-jet speed ratio, 0.4.

Fig. 10 MACA ‘ACR HO. E5E19

NATIONAL ADVISORYCHITTEE FOR AERONAUTICS

.6

J 3.0 . [x I x u,x x x u

).4

2.$!c * . c

1,4

.3 I I I I I I—.

(a) Blade-to-jet speed ratio, 0.2.

PliPd

3.0

> >: x Y — — — - — — b-

- — —? ‘2.2 x Y 0Y

d.5 :/ . 7 / , > x 1.4 x >. x

3

.4 F

speed ratio,’0.3.

I I I I I I I

R’ -- (b) Blade-to-jet.;

2I I I I I I I I I I I I I I I I

o t P* P.c .7CJ

c:

(OF abs.)(in. Hg abs.

.40 550 27.3

(c) Blade-to-jet speed ratio, 0.4.t 1000 57.5x 1200 lU to 60c1 1400 18.6

- 2 ;::26.8

.7 .18.6

v 1s0’2Py fPd

26.8v 2000 26.8

3, 00

.6 :/ -

— — x 2.2 u

= 5 . — - x > x x

1,~ ‘_X ()

.5 _x

>

/ vL-x *

>

.4

.cm .006 .008 .010 .012 .OIA .016 .018 .020 .022 .024 .026

l.l,(ti. @ abs&(OF abs. )1.1P1/Ti(d”)Blade-to-jet speed ratio, 0.6.

Figure IO.- Variat%on of turbine efricienoy with Reynolds number factm.

NACA ACR Ho. E5E19 Fig. II

.6

.5

.4

.3

1.1

1.(

WATIWAL AOVCSORYCWMITTES F* ACRWAUTICS

) 01 .2 .3 .4 .5Blade-to-$et speed ratio, u/v

(a) Variation of efficienc stanaard with blade-to-

7T 101, 0.009.jet ‘peed ‘atio; pi 1

u/ v● 4—● s—

)04 .Ooa .012 .016 .080 ● 024 ● 026

P@il”lS (~. m ab~.)/(% @-.)lO1(b) Variationof the efficiencyratiowith the

Reynoldsnumberfaotar.

F@ure 11.- Turbine-efficiencyccwrelatiom.

1

Fig. 12 NACA ACR No. E5E19

NATIONAL ADVISORYCWITTEE FOR AERONAUTICS

.7

.6

f=

: .50c2aA%hala) .4‘G+D

2

.3

d

.2n , 1 1 1 , , I , , 1 a I n 1 I 1 1 1 I 1 a 1 , , a . , 1 , , 1 a a a & 1 1 , I Sk

o ●1 .2 .3 .4 .5 .6Blade-to-jet speed ratio, u/v

Figure 12.- Comparison between calculated and experimental data.Inlet total pressure, 43.3 fnc es mercury absolute; Inlet temp-

Perature, 1200° F absolute; pi pd$ 3.0.

NACA ACR No. E5E19 Fig. 13a,b

—NATIONM AOVISORY

COMMITTEE FOR AER~NJTICS I

4

v 1200 43

—L e

3R

- ‘f? J=q! -+$ e A ,&

2(a) Test data ror inlet-temperature range, 1200° to 2000° F absolute; Inlet

total-pressure range, 10 to 63 inches of mercury absolute.

Pi/Pal

o 1.4+ 2.2x 3.0

3.9~ 5.4 P ./Pd

3.0 to 5 ,4

3 7 ~ - ‘~—

9 - T - v—

+– -+2.2

+

u a o3 0 1.4

22,9W 6,090 10,OW 14,W0 16,000

Fw~wrpm

(b) Teat datafor inlet temperature, =6300 F absolute.

Figure M.- Correlation of the gas-flow deta.

I

Fig. 13c,d

NATIONAL AOVISORYCObwlTTEE FOR AERONAUTICS

H

3.2(rpm )

2.8+10 ,000-12,000

2.4

2.0(c) Cross plots for inlet temperature raw, 1200° to 2000° F absolute;

inlet-pressur9 rsnge, 10 to W inches of’ mercury absolute.

3.2

2.e

2.4

2.02 3 4

pres6ure ratiO# Plhd

(d) Cross plots for Inlet temperature, 550° F absolute.

Figure1.3.- Concluded. Correlationof the gas-flowdata.

NACA ACR NO. E5E19 Fig. 14NATIONAL ADVISORY

COWITTEE FOR AERONAUTICS.’7

.6

.s

.4

.3

.6

.3

.6

.5

.4

.3

(a) Inlet temperature, 1200° F abgolute.

[

(b) Inlet temperature, 1600° F absolute.

o .1 .2 .3 .4 .s .6 .7 .eBlade-to-jet speed ratio, u/v

(c) Inlet temperature. 1800° F absolute.

Fi ra 14. - Comparison ot tests uSlng lneulated nozzle box with those using uninsulated nozzle%x. ~e..ure rat~o,2.2; lnlettotal pressure, 26.8 inehesmrcury absolute.

‘1

Fig. 15 NACA ACR NO. E5E19

1

1

1

:gur

rat

to

of

NATIONAL ADVISORY , # , # , , , , v , , , ,

COWITTEE FOR AERONAUTICS

Ti PI(q abs. )(in. Hg abs.)

o 1200 27+ 1600 27x 1800 27

Pi ~pd8

2000 271200 10 *L

A 1200 ‘lg5 ,2 )(

%v 1200 35

\, ~7 1200 43

.2 , w 1200 52D 1200 60

\y’

/

\ 1 0

3 .9 /

‘x.. .?

x \A. \

Q 33 .0

x “-9- –P

!* 17

2 2 -$yi [ **.t ~ v

J!@ qp ax q&–m<

I

1.4n 4

m 1 t , t , , , , 1 , , ,I- o 1 , , , 1 , , I # Io .1 .2

J+●3 .4 .5

Blade-to-jet speed ratio, u/v

‘e 15.- Variation of the ratio rI?/v with the blade-to-jet speedL1O for various pressure ratios. Inlet-temperatur-

10 ;Q%%c;::oo2000° F absolute; inlet total-pressure ?ange,mercury absolute.

Illllllllllml[lmlm3 117601354 1827

I