25 MAR T94B NATIONAL ADVISORY COMMITTEE FOR AERONAUTICS WARTIME REPOR ORIGINALLY ISSUED. December 1945 as Advance Restricted Report E5K06

Transcription

1 <*$5ft&E?7LWSSt*^ ffijggfficsa»«1 '' ARR N. E5K06 25 MAR T94B 1 «NATIONAL ADVISORY COMMITTEE FOR AERONAUTICS WARTIME REPOR ORIGINALLY ISSUED December 1945 as Advance Restricted Reprt E5K06 CALCULATIONS OF THE PERFORMANCE OF A COMPRESSION-IGNITION ENGINE-COMPRESSOR TURBINE COMBINATION I - PERFORMANCE OF A HIGHLY SUPERCHARGED COMPRESSION-IGNITION ENGINE By J. C. Sanders and Alexander Mendelsn Aircraft Engine Research Labratry- Cleveland, Ohi WASHINGTON NACA WARTIME REPORTS are reprints f papers riginally issued t prvide rapid distributin f advance research results t an authrized grup requiring them fr the war effrt. They were previusly held under a security status but are nw unclassified. Sme f these reprts were nt technically edited. All have been reprduced withut change in rder t expedite general distributin. NACA LIBRARY LANGLEY MEMORIAL AEROJ AERONAUTICAL E "234 LABORATORY Laagley Fjjjkj, ya.

2 J NACA ARB N. E5KD6 NATIONAL ADVISORY COMMITTEE FOB AERONAUTICS ADVANCE RESTRICTED EEPORP. CALCULATIONS OF TEE PERFORMANCE OF A COMEBESSION-IGNTTION i ENGINE-COMPRESSOR TURBINE-COMBINATION I - PERFORMANCE OF A HIGHLY SUPERCHARGED COMPRESSION-IGNITION ENGINE By J. C. Sanders and Alexander Mendelsn SUMMARY Small high-speed slnr" -cylinder cmpressin-ignitin engines were tested t determine their perfrmance harateristics under high supercharging. Calculatins were made n the energy available in the exhaust gas f the cmpressin-ignitin engines. The maximum pwer at any given maximum cylinder pressure was btained when the cmpressin pressure was equal t the mftt-itrmtn cylinder pressure. Cnstant-pressure cmbustin was fund pssible at an engine speed f 2200 rpm. Exhaust pressures and temperatures were determined frm an analysis f indicatr cards. The analysis shwed that, at rich mixtures with the exhaust bak pressure equal t the inlet-air pressure, there is excess energy available fr driving a turbine ver that required fr supercharging. The presence f this excess energy indicates that a highly supercharged cmpressin- Ignitin engine might be desirable as a cmpressr and cmbustin chamber fr a turbine. INTRODUCTION In view f the current interest in aircraft-prpulsin systems that utilize gas turbines In the energy-cnversin prcess (reference 1), the develpment f a means f supplying gas-at pressures and temperatures suitable fr turbine peratin is desirable. The physical prperties f materials available fr turbine blades limit the ma-rinnim permissible gas temperature t apprximately 1600 F. In a cmbustin-gas-turbine system cnsisting f a cmpressr, a cmbustin chamber, *»r^ a gas turbine, the temperature is maintained belw the specified limit by supplying excess air. This limited temperature reduces the available energy in the gas that can be extracted

3 NACA ARR N. E5K06 by the turbine and fr this reasn highly efficient turbines and cmpressrs are required t btain ver-all perfrmance appraching that f the reciprcating engine (reference 2). A dual pwer unit cnsisting f a highly supercharged cmpressinignitin engine geared t a turbine is prpsed. The cnditins f the wrking cycle wuld be s adjusted that the turbine, supplied with the exhaust gas frm the engine, wuld prduce a large prpr-' tln f the pwer. The mpressin-ignitin engine is prpsed fr use in this engine-turbine cmbinatin because it can perate at high pressures withut the ccurrence f knck and preignitin. Sme cntrl f the temperature f the gas entering the turbine can be effected by varying the fuel-air rati f the mixture burned in the engine. This plan fr a dual pwer unit, which is nt new, is mentined In reference 1. A preliminary evaluatin f the desirability f a cmpressin- Ignitin engine-turbine cmbinatin requires knwledge f the engine perfrmance with high inlet-air pressures and requires-infrmatin n exhaust-gas temperatures and pressures. Infrmatin n exhaust-gas temperatures and pressures and a dlsussin f the perfrmance characteristics f a highly supercharged mpressin-ignitin engine are presented herein. N test data n perfrmance at inlet-air pressures abve 50 Inches f mercury abslute were available fr the cmputatins, Tests were therefre cnducted n tw small high-speed cmpressin-ignitin engines t determine the perating characteristics at inlet-air pressures up t 90 Inches f mercury abslute. Particular emphasis was placed upn peratin n the cnstant-prssure cmbustin cycle in an effrt t prduce high indiated mean effective pressures withut excessive maximum cylinder pressure, Indicatr cards were analyzed t btain exhaust temperatures and pressures. These tests were run at the NACA Langley Field labratry during the summer f N attempt is made herein t estimate the perfrmance f the engine-turbine cmbinatin. APPARATUS Tw fur-strke-cycle cmpressin-ignitin engines were used in these tests. One, which had a cmpressin rati f 13.1, cnsisted f a single water-cled cylinder munted n an NACA universal test engine crankcase. High turbulence in the cmbustin chamber was pr* ducd by the use f a displacer-type pistn shwn in figure 1 and mre fully described in reference 3. The bre was 5 inches and the strke 5g inches. The ther englnu, which had a cmpressin rati f 15, used an air-cled cylinder with the same type f cmbustin chamber as the water-cled cylinder and had a bre f 5j Inches and a strke f 5y inches.

4 NACA ARB N. E5KD6 The simultaneus discharge frm "bth cylinders f a twcylinder high pressure injectin pump with plungers 11 millimeters in diameter metered fuel t a differential-area injectin valve, vhich was spring-laded t have an pening pressure f 2500 punds per square inch. A multiple-rifice nzzle, designated K-4 in table I f reference 4, was used because it was fund that this nzzle gave a gd mixing f the fuel with the air. The usual labratry equipment was emplyed t measure pwer and fuel cnsumptin. Cmbustin air was supplied at high pressure frm a central supply system. Inlet-air pressure was measured at the surge tank and the air was unheated. Maximum cylinder pressures «Tifi indicatr cards were btained with a mdified Farnbr engineindicatr described in reference 5. PROCEDURE Pur series f tests were run, three at a cmpressin rati f 13.1 and ne at a cmpressin rati f 15. In the first series f tests inlet-air pressure, fuel flw, and injectin advance angle fr maximum pwer at- several maximum cylinder pressures were determined with the engine having a cmpressin rati f A maximumpwer best at a cmpressin rati f 15 and a maximum cylinder pressure f 1225 punds per square Inch abslute was run in the secnd series f tests t shw the effect f cmpressin rati n maximum pwer. In the third series the effect f injectin advance angle, fuel-air rati, and inlet-air pressure n fuel cnsumptin nt a maximum cylinder pressure f 1400 punds per square inch abslute was determined. Indicatr cards t shw the effects f inlet-air pressure and injectin advance angle n cmbustin were btained during the furth series f tests. The last tw series f tests were run n the engine having a cmpressin rati f 13.1'; All tests were run at an engine speed f 2200 rpm and atmspheric exhaust. Maximum-pwer tests at lw cmpressin rati. - At each f a number f fixed inlet-air pressures in the range frm 45 t 80 inches f mercury abslute and with the fuel flw adjusted t give maximum pwer, the injectin timing was advanced until an arbitrarily chsen maximum cylinder pressure was btained. The inlet-air pressure, brake mean effective pressure, Injectin advance angle, and maximum cylinder pressure were recrded. The tests were repeated at successively higher inlet-air pressures; the injectin was retarded in each case, until the inlet-air pressure culd nt be further increased withut increasing the maximum cylinder pressure, regardless f hw much the injectin was retarded. Similar tests were run at maximum cylinder pressures f 770, 955, 1135, 1225, 1315, and 1410 punds per

5 NACA ABB N. E5K06 square Inch abslute. The engine having a cmpressin rati f 13.1 was used fr these tests. The indicated mean effective pressure vas calculated frm the indicated pwer btained by adding the measured brake pver and the mtring pwer required t drive th engine at test speed and at test inlet-air pressure when n fuel was injected. Frictin tests were made with a cld engine because ignitin f the lubricating il Interfered with mtring measurements when the engine was warm. Maxlmum-pwer tests at high cmpressin rati. - The maximumpwer tests were cnducted at a cmpressin rati f 15 in the same manner as the maximum-pwer tests at a cmpressin rati f 13.1, except that the nly value f maximum cylinder pressure tested was 1225 punds per square inch abslute. Fuel-cnsumptin test. - Fuel-cnsumptin characteristics were btained at Inlet-air pressures f 68.2, 73, 76.5, 81.4, and 84.4 inches f mercury abslute. At each inlet-air pressure, sufficient fuel was injected t prduce maximum pwer and the injectin timing was adjusted t give a maximum cylinder pressure f 1400 punds per square inch abslute. Observatins were made f ful cnsumptin at varius lads at the Inlet-air pressure and the injectin timing thus btained. Indicatr-card tests. - Tw series f indicatr cards were btained. All the cards in ne series were taken n cycles having peak pressures f 1415 punds per square Inch abslute. At Inletair pressures f 45, 60, 70, and 80 inches f mercury abslute, the Injectin was advanced until a meximu cylinder pressure f 1415 punds per square inch abslute was btained and Indicatr cards were taken. The fuel flw was that fr maximum pwer at each inlet-air pressure. The ther series f indicatr cards was btained with the injectin-advance angle s adjusted that cmbustin was as near cnstint pressure.as pssible. These Indicatr cards were btained at inlet-clr pressures f 48, 58, 70, 73.6, and 80 inches f mercury abslute and maximum-pwer fuel flw. POVER AND FUEL-CONSUMPTION GHABACTERISTICS Maximum-pwer tests. - Figure 2 shws that at any given maximum cylinder pressure between 770 and 1410 punds per square inch abslute, the maximum pwer was attained when the cmpressin pressure was apprximately equal t the maximum cylinder pressure. Fr example, at a maximum cylinder pressur f 1225 punds per square Inch abslute, the maximum pwer was btained when the Inlet-air pressure

6 NASA AKR Nc. E5E06 was 75 inches f mercury abslute and the.crrespnding cmpressin pressure withut fuel was Ü70 punds ppr.square inch abslute, which indicates that the'engine was perating n apprximately a cnstant-pressure cmbustin cycle. Because the cmpressin pressure in the ylinder while the engine is under pwer is- slightly higher, than the cmpressin pressure while the engine is being mtred, the real agreement between the maximum cylinder pressure and the cmpressin pressure is clser than is shwn by figure 2. The limit f supercharging fr a given maximum cylinder pressure is reached when the cmpressin pressure equals th maximum cylinder pressure. In all these tests the highest pwer was reached at the limit f supercharging as shwn In figure 2, Evaluatin f the pwer characteristics f the cmpressinignitin engine by cmparisn with a spark-ignitin engine may b btained frm figure 3. Fr the same pwer the spark-ignitin engine requires an inlet-air pressure abut 8 percent lwer than the cmpressin-ignitin engine when the injectin is advanced t give a cnstant-vlume cmbustin cycle. When the injectin is retarded t simulate a cnstant-pressure cmbustin cycle, hwever, the Inlet-air prssure required fr the same pwr by the cmpressinlngitin engine is 25 percent greater than that required by the spark-ignitin engine. Jjfbn a maximum cylinder pressure is achieved in the cmpressin-ignitin engine as lw as In the spark-ignitin engine, this lss must be incurrd. As can be seen frm figure 3, the cmpressin-ignitin engine with a cmpressin rati f 13.1 has abut the same rati f maximum cylinder pressure t indicated mean effective pressure as a spark-ignitin engine with a cmpressin rati cf 6.4. The maximum-pwer fuel-air rati is used in each case. Effect f cmpressin rati n pressure-limited pwer. - The effect f cmpressin rati n the maximum pwer btainable with a given maximum cylinder pressure is illustrated In figure 4. The maximum indicated mean effective pressure attainable with a maximum cylinder prssure f 1225 punds per square inch abslute is 264 punds per square Inch at a cmpressin rati f 15 and 300 punds per square inch at a cmpressin rati f The crrespnding Inlet-air pressures were 62 and 75 inches f mercury abslute, respectively. Thse data illustrate that,because a higher inlet-air pressure can be usd,mre pwer can be btained by using a lw cmpressin rati fr a. highly supercharged cmpressin-ignitin engine delivering exhaust gas t a turbine than by using a high cmpressin rati. The minimum cmpressin rati f a cmpressin-ignitin engine is limited by th ignltibllity f the cylinder charge. Starting becmes difficult In warm climates when the cmpressin rati is less than 12

7 NACA ARK N. E5X06 and in cld climates when the cmpressin rati is belw 14 unless an air preheater is used. Fr increased pwer utput fr the cmpressin-ignitin engine-turbine cmbinatin, lwer cmpressin ratis seem desirable and may be practical if a ht plug is used t ignite the fuel. Fuel cnsumptin. - The fuel-air ratis were cmputed, assuming a vlumetri efficiency f 0.90, and were pltted with fuel cnsumptin «rid inject In-advance angle in figure 5. The reciprcal f the indicated specific fuel cnsumptin was used because the reciprcal is prprtinal t the indicated efficiency. This figure clearly shws that, when ^he injectin is retarded, the indicated efficiency is reduced. Figure 6 shws the vlumetric efficiency fr a similar type engine. Indicatr-card tests. - An example f an riginal recrd btained with the Farnbr indicatr is shwn in figure 7; recrds presented in such frm are indistinct. The curves n the indicatr cards btained (figs. 8 and 9) were therefre drawn by hand t represent the mean f the pints generated fr each test cnditin by the Farnbr indicatr. The pressure scales are nt liear in the lw ranges. Figure 6 shws that, when the inlet-air pressure is increased and the injectin retarded, the cycle changes frm an apprximatin' f the cnstant-vlume cmbustin cycle t a cnstant-pressure cm-. bustin cycle. It is nt always pssible, hwever, t btain a cnstant-pressure cmbustin cycle with a retarded injectin, as shwn in figure 9. At lw maximum cylinder pressure, a large delay in ignitin f the fuel injected resulted in mst f the fuel igniting at ne time and causing a sharp rise in pressure. The injectin cnsequently was cnsiderably retarded after tp center t prevent the wigf*"» cylinder pressure frm exceeding the cmpressin pressure. A test at a maximum cylinder pressure lwer than 770 punds per square inch abslute was attempted but it was fund necessary t retard the injectin t Buch an extent that ignitin was irregular as a result f the lw cmpressin temperature during injectin. The data frm the Farnbr indicatr fr a cnstant-pressure cmbustin cycle were transferred t a pressure-vlume basis and are presented in figure 10. A true Diesel cycle was nt attained because the expansin after cut-ff was isthermal (the expansin expnent being apprximately 1.0) resulting frm the cntinuatin f cmbustin during the xpnsln strke. The isthermal expansin is undesirable buccuse the ecnmy and pwer at a given maximum cylindr pressure are lss than thse btained with a true Diesel cycle having adlabatlc expansin. The clse apprach t the Diesel cycle shwn by the indicatr diagram in figure 10, hwever, is cnsidered

8 NACA ARB N. E5K06 remarkable fr a small cmpressin-ignitin engine perating at a high engine speed f 2200 rpm. Energy available in the exhaust gas. - The energy available in the exhaust gas was btained by analysis f an indicatr card. Observatins f exhaust-gas temperatures as measured by a thermcuple culd nt be used fr this purpse because temperature measured In this manner. Is much lver than the true value, as is explained in reference 6. A descriptin f the methd f analyzing the indicatr cards is given in appendix A and the results f this analysis are shwn in figures 11 and 12. Frm figure 11 the release temperature and pressure may be btained fr cmputatin f exhaust temperature and energy available at varius perating cnditins. Such cmputatins were made fr the special case f a fuel-air rati f and sea-level ambient pressure with lntake-manlfld and exhaust-manifld pressures equal. The methd f making this cmputatin is described in appendix B and the results are shwn in figure 12 tgether with the energy required fr supercharging. The energy available in the exhaust at high inlet-air pressures exceeds the required supercharger pwer. The cmbined efficiency f a representative supercharger and turbine is 50 percent. The required energy t the turbine, cmputed by dividing the energy required fr supercharging by 0.5, is shwn t be less than the available energy, thereby indicating the pssibility that the turbine can develp excess energy, which culd be used t augment the pwer f the engine, particularly at high inlet-air pressure. SUMMARY OF RESULTS Frm the tests made n small high-speed cmpressin-ignitin engines t determine the suitability f this type f engine fr use In an engine-gas turbine cmbinatin, the fllwing results were btained: 1. The maximum pwer attainable in a cylinder with maximum pressure limited by structural strength was btained by supercharging until the cmpressin pressure equaled the maximum cylinder pressure. The lwest rati f maximum cylinder pressure t indicated mean effective pressure was 4 when the cmpressin rati was Engine peratin with apprximately cnstant-pressure cmbustin was fund pssible with the displacer-type chamber at n engine speed f 2200 rpm.

9 NAß A ABB N. E5B06 3. The exhaust energy available with rlh mixtures at sea level with the exhaust hack pressure equal t the Inlet-air pressure exceeded the energy required t drive a turbsupercharger. Aircraft Engine Research Labratry, Natinal Advisry Cmmittee fr Aernautics, Cleveland, Ohi.

10 NACA ABE N. B5K06 APH5NDU A INDICATOR-CARD ANALYSIS In rder t find, the temperatures and pressures "befre release, an analysis f Indicatr cards was made. The release pressure cannt he diretly read frm the indicatr cards htained with a mdified Farhbr engine Indicatr because the pressure scale is inaccurate belw 300 punds per square inch. An analysis was made f the cycle shwn in figure 10 using the fllwing symbls: n expnent fr cmpressin strke in equatin FT 11 = k n e expnent fr expansin strke v c vlume abve pistn at cut-ff v clearance vlume v^ r c r T^ displacement vlume cut-ff rati, T c c T c + v d cmpressin rati, v c temperature at release, Tl P. pressure at release, lbsq ft abslute T]_ inlet-air temperature, R P, inlet-air pressure, lbsq ft abslute Experimental values f n e, n Q, and r 0 fr rich mixtures were btained frm Indicatr cards taken in the tests reprted herein. The cards used fr lean mixtures were taken frm figure 4 f reference 7. These cards were taken with an ptical indicatr with the engine under pwer fr nly ne cycle. The cmpressin rati was The expnent n c was fund t be apprximately 1.35, as shwn In figure 13. Figure 13 als shws n fr a range f fuel-air ratis frm 0.058i t The value f the cut-ff rati was available nly fr rich mixtures frm the indicatr ards btained in the present test. It was assumed that the cut-ff rati is cnstant fr rich mixtures and Is prprtinal t the fuel-air rati up t the theretically crrect mixture. The variatin f n Q, n c, and r Q with fuel-air ratis are shwn in figure 14.

11 10 NAD A ABR N. E5K06 Release temperatures and pressures fr mst perating cnditins at e cmpressin rati f 13.1 are pltted in figure 11. These values were btained hy substituting the experimental values f the cnstants frm flgure- - 14, in the fllwing equatins: T 4 = Tir^-^rc" 0 (1) P* =?! (2) With this infrmatin, the exhaust energy can he calculated fr almst any cnditin.

12 NACA ARE N. E5K06 11' APPENDIX B CALCULATION OF EXHAUST-GAS TEMPERATURE AND AVAILABLE ENERGY Th temperature f the exhaust gas can he calculated frm the cnditins "befre release. During the release prcess tw actins ccur. Eich small vlume f gas escaping frm the cylinder Is assumed t underg a free expansin with practically n change f temperature. The gases remaining In the cylinder underg an apprximately adiahatic expansin. The relatin between the temperature and the density will then be apprximately as shwn in the fllwing figure: T Bth th temprature T and th density P decrease until the pressure becmes equal t the xhaust pressure. The temperature remains cnstant while the remainder f the gases are exhausted frm th cylinder. The cver?g teraperctur cf the exhaust gas can therefre be btained by intgr.iting th area under th curve and dividing by the '-.bsrisgr. The equatin fr the average temperature Is derived as fllws: T. av 05 Tap + Tgpg (1) P 4 -* Frm the gas equatins: T = T, T 5 ün*r

13 12 NACA ABB N. E5E06 Substituting the ezpreasin fr T, T g,' and p g in equatin (l) and integrating T 1 ] + (7-D rr\ (2)» 7 (_ When the release cnditins and the exhaust-hack pressure are knwn, the exhaust-gas temperature can he calculated frm equatin (2). The values f 7 were btained frm figures 2 and 4 f reference 8. After the exhaust-gas temperature was calculated frm equatin (2), tht«energy available fr a turbine cycle was btained frm figure 9 f reference 8. The results are shwn pltted in figure 12. REFERENCES 1. Smith, G. Geffrey: Aircraft Prpulsin Systems. An Examinatin f the Pssibilities f the Cmbustin Gas Turbine: Turbines in Cnjunctin with Airscrews. Flight, vl. XLII, n. 1764, Oct. 15, 1942, pp Pining, Werner: The Efficiency f Cmbustin Turbines with Cnstant-Pressure Ctmbuatin. NACA TM N. 975, Mre, C. S., and Pster, H. H.: Perfrmance Tests f a Single- Cylinder Cmpressin-Ignitin Engine with a Displacer Pistn. NACA TN N. 518, , 4. Fster, H. HY: The Quiescent-Chamber Type Cmpressin-Ignitin Engine. NASA Rep. N. 568, Cllins, Jhn H., Jr.: Alteratins and Tests f the "Farnbr" Engine Indicatr. NACA TN N. 343, King. W. J.: Measurement f High Temperatures in High-Velcity Gas Streams. A.S.M.E. Trans., vl. 65, n. 5, July 1943, pp Rthrck, A. M., and Waldrn, CD.: Effects f Air-Fuel Rati n Fuel Spray and Flame Frmatin in a Cmpressin-Ignitin Engine. NASA Rep. N. 545, Pinkel, Benjamin, and Turner, L. Richard: Thermdynamic Data fr the Cmputatin f the Perfrmance f Exhaust-Gas Turbines. NACA ARR N. 4B25, 1944.

14 01 Side End Figure! -Cmbustin chamber In the water-cled cylinder. NATIONAL ADVISORY COMMITTEE FOR AERONAUTICS

15 Fig. 2 NACA ARR N. E5K06 (0 > (0 w > t.. > *-\ 43 O 0) «H <M V c nl 4) E O 11) +3 «'S ^00 c i 1200 (0 iß m & a M^ ^" I4.00 -s* 30 J+0 50 T 70 S 90 Inlet-air pressure, in. Hg abs. Figure 2. - Effect f Inlet-air pressure n maximum pwer and cmpressin pressure in a pressure-limited cycle. Cmpressin rati, 13.1; engine speed, 2200 rpra; inlet-air temperature 95 P.

16 NACA ARR N. E5K06 in in Q. M <D a c H C u s> EH X lj Indicated mean effective pressure, lbsq in. Figure 3«~ Cmparisn f inlet-air pressures and maximum cylinder pressures in cmpressin-ignitin and spark-ignitin engines.

17 Fig KACA ARR N. E5K06 NATIONAL ADVISORY COMMITTEE FOR AERONAUTICS Jmpr issl i rat L <a 4> M 0) 6. > *» c > u 4» -a a> 4» « A, > *7 1» * y V <" i-o Inlet-air pressure. In. Hg aba, Figure k» " Effect f cmpressin rati n the maximum pwer btainable frm pressure-limited cycles in a cmpressin-ignitin engine. Maximum cylinder pressure, 1225 punds per square inch; engine speed, 2200 rpm; inlet-air temperature, 95 P.

18 NACA ARR N. E5K06 Fi g 3.U 3.0 NATIONAL ADVISORY COMMITTEE FOR AERONAUTICS A\ c\ k. \^ k X n J Inlet -air pres sure n.hk abs. 8k 81 k k *.0 O InJ< advi ictlol 1 ince t ingle de« V \\\ P. 2.2 S3 w 1.8 l.k ^ s v \ ^ \ V ^ K N V K ^ V. *r» Puel-alr rati Figure 5.- Effect f Injectin advance angle and fuel-air rati n fuel cnsumptin f cmpressin-ignitin engine when maximum cylinder pressure is maintained at II4.OO punds per square inch. Cmpressin rati, 13.1; engine speed, 2200 rpm.

19 Fig NACA ARR N. E5K06 NATIONAL ADVISORY COMMITTEE FOR AERONAUTICS C 0> O > DO lk 0 Brake mean effective pressure, lbsq in. Figure 6.- Vlumetric efficiency f cmpressin-ignitin engine with displacer type pistn. Engine speed, 2250 rpm; Inlet-air pressure, I4.O inches mercury abslute.

20 Ü2 Ott c S n 8 8 _ Pressure, lb sq In. 8-»-3 ' *< \ O s» M ^ r 1 O **! 1 & O _ er.*... c+ O LJ. * 3 e> K 2 5- P^ 1 *S8? M* S.cu ' H t- 1. r a H-«er. l a. * 1 _..*T*.Hu 0> 1:,'' *» t 3 ;} er ; '» 1 cnl! "* ^ M-.1 3 P- ; *- " S gf ; O! :.».. ^!; y 1 i *. " O ;ü 3 5 m I * r f. > m < i i M L '»!J 90)193 a 0N HHV VOVM

21 Cylinder pressure, lbsq In Inlet-air pressure, In. Hg abs, 80 imep, lbsq in, NATIONAL ADVISORY COMMITTEE FOR AERONAUTICS 0 20 Crank angle, deg Figure 8.- Effect f inlet-air pressure n cyclic pressure when the maximum cylinder pressure is held at 1310 punds per square inch. Cmpressin rati, 13.1; engine speed, 2200 rpm; inlet-air temperature, 95 0 P. > > 3D SO W

22 Cylinder pressure, lbsc sq in. 400 Inlet-air pressure, in. Hg abs. imep, lbsq in. SO O 58.O 48.0 Z M 21 ZkO 190 CJ1 O NATIONAL ADVISORY COMMITTEE FOR AERONAUTICS 0 20 k0 Crank angle, deg Figure 9.- Effect f maximum cylinder pressure n cyclic pressure when the maximum cylinder pressure equals the cmpressin pressure» Cmpressin rati, 13.1; engine speed, 2200 rpm; inlet-air temperature, 95 F. <D

23 Fig. 10 NACA ARR N. E5K06 luoi 1200 Ul 1000 V) t a> u a h <D c. 3 Zj.00 NATIONAL ADVISORY COMMITTEE FOR AERONAUTICS O l 2 3 I* 5 6 Vlume abve pistn, arbitrary units Figure High-pressure diagram btained with Parnbr indicatr and translated t pressure-vlume card. Cmpressin rati, 13.1; engine speed, 2200 rpm; inlet-air pressure, 80 inches mercury abslute; inletair temperature, 95 0 P; measured indicated mean effective pressure, 535 punds per square inch; area f card, 8.7I4. square inches; equivalent mean effective pressure, 318 punds per square inch.

24 NACA ARR N. E5K06 Fig. II _ Pre ssure at release Teir perat ure at release NATIONAL ADVISORY COMMITTEE FOR AERONAUTICS 2000 O 0> (O <a > V) u ft *-c O <fl. e ll In Let-a. Lr pr 3SSUT In. *g ab 5. On 80 UU l r t 1 i 160 i y ^ 120 S^ 80 K 'j 4) 3 (0 t JO ai er t O (-t 10 V k, 800 ) k b Fuel-air rati Figure Release temperatures and pressures estimated frm an analysis f Indicatr cards btained n a cmpressinignitin engine. Cmpressin rati, 13«1; inlet-air temperature, 95 P.

25 Fig. 12 NACA ARR M. E5K06 NATIONAL ADVISORY COMMITTEE FOR AERONAUTICS u <u a E «j +5 « P w 3 1U00 T? nergy -- E nergy aval (lable extr acted in e Khaus t by t urbs uperc harge r cd L60 3 «120 cd > cfl >* w ^ "" ^ ^-^ c 0) p «1 3 <0 JS ä k.0, -" - ""^ ^ ^ 0 k D 5< D 6( ) 7< D 8 D 90 Inlet-air pressure, in.hg abs. Figure 12.- Exhaust-gas temperatures and energy available t turbine estimated frm analysis f indicatr cards btained n a cmpressinignitin engine. Cmpressin rati, 13.1; fuel-air rati inlet-air temperature, 95 p; engine speed, 2200 rpm; exhaust back pressure is equal t the inlet-air pressure.

26 MACA ARR N. E5K06 Fig. 13 V) 9 Curve Fuel -air ra tii 1 Ann A 0,0*if \ 1, 111 B \ ^ C 019 B 1. L0 \ lj.00 D Ö1C 6 1. \t \ s, \\ 300 E \ h \\\ V \\ ^ ft e AN NATIONAL ADVISORY COMMITTEE FOR AERONAUTICS 200 \ S \ X \* Cmp 'ess in s ;r< ke. n c 1 f\.3 5 \ \ ^. \\ \,\E * \ \ \\ \ \ N \\ 80 v V v V ^ \ N,\ \ s s s\ An V \ \ s\ N \ \ k $0 \ \ \ \ s. v 1 \ \ \ \\ \ \ ^ V. N s \ \ \ in.1.k Vlume, arbitrary units h Figure Variatin f expansin expnent n e with fuel-air rati. Cmpressin rati, (Data frm reference 7.)

27 Fig. 14 HACA ARR N*. E5K06 NATIONAL ADVISORY COMMITTEE FOR AERONAUTICS c c & 4> u 4-> >» 1.1* v_ \ \ N n Jt 1 "c n e > Vi I i.u - " ,k.06 Puel-alr rati Figure ll.. - Effect f fuel-air rati n cycle expnents and cut-ff rati f cmpressin-ignitin engine.

28 caanr EnraciaTHEi QIZBTOICTED Nattal Adteäss? Cmmittee fr Aernautics, Lewis FSSgM Prpulsin Lab., Cleveland, O. THE PERFORMANCE OF HIGHLY SUPERCHARGED COMP'iESSBDN-IGNITEDN ENGINES AMD THE EX- HAUST ENERGY AVAILABLE FOR A TURBINE - AND APPENDIX A AND B, by 7. C. Sanders and Alexander Eäcsrflslsn. Jan MM5. 26 pp. RESTRICTED L Sanders, 7. C. H, Mendelsn, Alesander DIVX3I0N: POCTS? Pteäsis, FscSprccalSag (8) SECTION: Prfrmaaca (13) DXSTMBUTXON: U. S. ESBitäry Orgamteattas request cpies frm ASTKA-BSC. CJhess rv&e requests t ASTXA-BSC»t AMC, TOTSgfcMfttamsa Air Frce Bass, Baytea,, O, Atta: NACA, cm scats TBCXM. CHOKHD eiav 8Sh.V,illl SüiiCE SOTEQ DOOTOCCTED