UNCLASSIFIED AD NUMBER LIMITATION CHANGES

Transcription

1 TO: UNCLASSIFIED AD NUMBER AD LIMITATION CHANGES Apprved fr public release; distributin is unlimited. FROM: Distributin authrized t U.S. Gv't. agencies and their cntractrs; Administrative/Operatinal Use; MAY Other requests shall be referred t Air Frce Arnld Engineering Develpment Center, Arnld AFB, TN. AUTHORITY aedc usae ltr 15 ct 1968 THIS PAGE IS UNCLASSIFIED

2 THE EFFECT OF HEAT RELEASE ON THE FLOW PARAMETERS IN SHOCK-INDUCED COMBUSTION By R. P. Rh des, P. M. Rub ins, and D. E. C h r is s Rcket Test Facility ARO, Inc., (J subsidiary f Sverdrup and Parcel, Inc. TECHNICAL DOCU ENTARY REPORT NO. AEDC TDR 62 7S 1 AFSC Prgram Area SOlA, Prjects 9751 & 6952, Tasks 3751 & (Prepared under Cntract N. AF 4(6}.8 S/A 24(61.73) by ARO, Inc., cntract peratr f AEDC, Arnld Air Frce Statin, Tennessee} ARNO EN INEERI ENT E AIR E SYSTEMS COMMAN UNITED STATES IR FORCE E

3 Qualified requesters may btain cpies f this reprt Orders will be expedited if placed thrugh the librarian member designated t request and receive dcuments frm ASTIA. r ther staff frm ASTrA. When Gvernment drawings, specificatins r ther data are used fr any purpse ther than in cnnectin with a definitely related Gvernment prcurement peratin, the United States Gvernment thereby incurs n respnsibility nr any bligatin whatsever; and the fact that the Gvernment may have frmulated, furnished, r in any way supplied the said drawings, specificatins, r ther data, is nt t be regarded by implicatin r therwise as in any manner licensing the hlder 1' any ther persn r crpratin, r cnveying any rights r permissin t manufacture, use, r sell any patented inventin that may in any way be related theret. 1'~=~6i~ ~6"f'i'!'6~ This dcument has been apprved fr public release and sale; its distributin is unlimited..-

4 AEDC TDR THE EFFECT OF HEAT RELEASE ON THE FLOW PARAMETERS IN SHOCK-INDUCED COMBUSTION By R. P. Rhdes, P. M. Rub ins, and D. E. Chriss Rcket Test Facility ARO, Inc., a subsidiary f Sverdrup and Parcel, Inc. May 1962 ARO Prject N AF - AEDC Arnld AF'S Tenn

5 AEDC.TDR FOREWORD This prject was partially funded by the Air Frce Office f Scientific Research under AFOSR Prject 9751 Task 3751.

6 AE DC. TDR ABSTRACT Experimental investigatins were cnducted in a Mach 3 cmbustin tunnel t determine heat release characteristics f a hydrgen-air mixture after it had passed thrugh a nrmal shck. Inlet temperature was varied frm 18 t 3 R. Heat release was indicated by three types f measurements: 1. Cmbustin and ttal temperature rise calculated frm gas analysis 2. Ttal pressure lss caused by heat additin 3. Ultra-vilet emissin at the OH emissin frequencies, indicating an H2-2 reactin Cmbustin efficiency was fund t increase with temperature and t be independent f fuel-air rati. Fuel passing thrugh an blique shck was bserved t emit a radiatin similar t that bserved frm the nrmal shck cmbustin. v

7

8 A E DC. TO R CONTENTS ABSTRACT... NOMENCLA TURE. 1. INTRODUCTION 2. APPARATUS AND PROCEDURE 2. 1 Supersnic Cmbustin Tunnel 2. 2 Test Fuel Injectin. 2.3 Wedges Instrumentatin Data Reductin.. 3. RESULTS AND DISCUSSION 3. 1 Flw Field Descriptin Fuel Distributin 3. 3 Cmbustin Effects 4. CONCL UDING REMARKS. REFERENCES APPENDIXES A. Calculatin Prcedures B. Analysis f Chemical Reactin Quench Rates in the Gas Sampling Prbe Page v xi ILLUSTRATIONS Figure 1. Supersnic Cmbustin Tunnel with Nrmal Shck Cnfiguratin Schematic f Nzzle and Test Sectin Shwing Nrmal Shck Cnfiguratin with Schlieren Pht f Shck System 3. Fuel Injectin Wedge 4. Single Wedge Used t Prduce Oblique Shck Waves Pressure and Sampling Prbe 6. Schematic f Pressure and Gas Sampling Equipment Mach Reflected Nrmal Shck Wave Variatin f Flw Parameters n Tunnel Centerline vii

9 A E DC TDR Figure 9. Effect f Preheater Temperature n Flw Parameters n Tunnel Centerline Ttal Pressure Prfile Aft f Nrmal Shck Wave Ttal Temperature Traverse - N Test Fuel a. Hrizntal. b. Vertical. c. Axial.... Preheater Gas Cmpsitin vs Ttal Temperature.. Preheater Gas Prperties vs Ttal Temperature. Fuel Distributin as a Functin f Tt 15. Variatin f Cmbustin Parameters acrss the Tunnel Width a. Lw Inlet Temperature Level.. b. Medium Inlet Temperature Level.. c. High Inlet Temperature Cmbustin Efficiency as a Functin f Inlet Temperature Variatin f Flw Parameters n Centerline with Test Fuel Cmbustin Variatin f Cmbustin Efficiency with Residue Time Aft f the Nrmal Shck Crrelatin f a Glbal Rate Equatin fr the Hydrgen-Oxygen Reactin Ttal Pressure Lss vs Fuel Cncentratin with Near-Zer Heat Release Ttal Pressure Lss vs Fuel Cncentratin at Varius Cmbustin Efficiency Values Crrected Ttal Pressure Lss vs Temperature Rati Three Inches Aft f the Nrmal Shck Variatin f Flw Parameters with Axial Distance Aft f Nrmal Shck Wave with Test Fuel... Cmparisn f Calculated Pressure Lss with Experimental Pressure Lss fr Heat Additin Aft f the Nrmal Shck a. Tt at shck 275 R. b. Tt at shck 235 R. Page viii

10 AEDC TDR Figure Test Sectin Schlieren and Emissin Phtgraph with Test Fuel On... Test Sectin Emissin Phtgraph with Test Fuel Off Test Sectin Emissin Phtgraph with Oblique Shck Wave Page ix

11

12 AEDC.TDR NOMENCLATURE at a 2 E Speed f sund at ttal temperature, ft/ sec Excess fuel ver stichimetric equivalence rati Glbal activatin energy, call gm mle g Dimensinal cnstant, Ibm ft/lbf sec 2 h Enthalpy, Btu/lbm mle M Mach number m mf p Prt Pt Pt Q r R l' Mlecular weight Mle fractin Pressure, psia Turbulent Prandtl number Ttal pressure behind a nrmal shck, psia Plenum pressure, psia Heat f reactin, Btu/Ibm mle Universal gas cnstant, energy /lbm mle R Temperature, R Tt Ttal temperature with =, R V x y z y Velcity, ft/ sec Axial distance behind shck wave, in. Vertical distance frm tunnel centerline, in. Preheater fuel cncentratin in equivalence rati Test fuel cncentratin in equivalence rati Hrizntal distance frm tunnel centerline, in. Specific heat rati Cmbustin efficiency f test fuel T{ Overall cmbustin efficiency, test fuel and preheater tuel Density, Ibm /ft 3 r [A] Time, micrsec Mles f cmpnent A per unit vlume xi

13 AEDC TDR (A) Vlumetric fractin f cmpnent A in mixture (dry) SUBSCRIPTS c p pf Centerline Test fuel nly Preheater nly Preheater and test fuel Ttal Initial cnditins Final cnditins Free stream xii

14 AEDC.TDR INTRODUCTION Althugh the chemical reactin rate f hydrgen has been studied fr many years, little infrmatin is available n the effect f the aerthermdynamics f a supersnic airstream n the chemical reactin rate. Many theretical analyses f devices using supersnic cmbustin have been made - fr example ramjet engines (Refs. 1, 2, and 3). Hwever, the prblem f hw this cmbustin can be stabilized and cntrlled has nt been slved. Althugh detnatins in shck tubes have been studied previusly, the attempt t wrk with "standing" waves is relatively recent. Nichlls (Refs. 4 and 5) used a nrmal shck wave prduced by a highly underexpanded free jet nzzle. Grss (Ref. 6) and Rhdes and Chriss (Ref. 7) used a nrmal shck prduced by the intersectin f tw wedge shcks. This reprt discusses the wrk dne in the Rcket Test Facility (RTF), Arnld Engineering Develpment Center (AEDC)' Air Frce Systems. Cmmand (AFSC), using the Supersnic Cmbustin Tunnel (SCT) as a cntinuatin f the wrk reprted in Ref. 7. Extensive data are presented n the flw field characteristics in the zne f the tw-wedge shck and n the chemical reactin rate f hydrgen-air mixtures in this flw field when the temperature level is high enugh.fr chemical actin t ccur. The wrk was directed tward establishing a simple aerdynamic mdel in which cmbustin phenmena culd be studied with uncmplicated instrumentatin which culd measure cnditins at a pint in the stream. In these experiments, the bjective was t verify whether heat release actually ccurred, and, if s, t what extent. This was dne by: 1. Sampling cmbustin gases thrugh a prbe specially designed t prmte rapid quench f the chemical reactins and determining ttal temperature and ther prperties f the gas frm an analysis f the gas cmpsitin; 2. Making extensive pressure surveys and cmparing the measurements t thse predicted by theretical equatins t determine whether deviatins were caused by heat release; and 3. Measuring the radiant emissin frm the reactin with a spectrmeter t determine whether radiatin was caused by OH in emissin, and hence that an H2-2 reactin was in prgress. Ultimately, knwledge gathered frm these studies culd be useful in the design f high-speed prpulsin systems. Manuscript released by authrs March

15 AE DC- TD R , APPARATUS AND PROCEDURE 2.1 SUPERSONIC COMBUSTION TUNNEL A detailed descriptin f the Supersnic Cmbustin Tunnel (Fig. 1) is presented in Ref. 7. Air, preheated by an indirect-fired heater t 146 R, enters the plenum where the cre f the nzzle airflw is further heated t a maximum f 35 R by the cmbustin f hydrgen. The nzzle is tw-dimensinal and initially had an exit area 3 in. wide by 5 in. high. It is perated as a free jet with a discharge Mach number f 3. 1 inside the test rhmbus. During these tests the tunnel width was increased t six inches. This did nt seem t have any effect n the flw parameters except t widen the zne in the center which was free f disturbances frm the sidewalls. The prcedure fr establishing the desired cnditins in the test sectin is described in detail in Ref TEST FUEL INJECTION A decisin was made early in the prgram t use a thin wedge fuel injectr installed in the supersnic zne f the nzzle (Figs. 1 and 2), rather than the tube fuel injectr near the tunnel thrat used in the tests reprted in Ref. 7. The purpse f this mdificatin was t reduce the pssibility f partial burning f fuel near the injectr where the static temperature was quite high. Sme experiments with thrat fuel injectin at the higher temperatures indicated that this type f partial burning was ccurring. A phtgraph f the fuel injectr is shwn in Fig. 3. Further analysis f the wedge aerdynamics will be fund in sectin WEDGES Tw types f wedges were used t prduce shck systems. The first was a single, water-cled, 3-deg wedge fr prducing an blique shck wave. This wedge was munted in a windw frame as shwn in Fig. 4. The secnd type cnsisted f a set f tw 25-deg wedges used t prduce a pair f blique shcks and a cnnecting nrmal shck. The shck system prduced and the lcatin f the wedges are shwn in Fig. 2. The phtgraph in Fig. 1 shws the wedges retracted frm the test psitin. 2

16 AEDC TDR INSTRUMENTATION All temperatures except the test sectin ttal temperature were measured with chrmel-alumel thermcuples and recrded n a recrding ptentimeter. The ttal temperature in the test sectin was calculated using the analysis f the gas as shwn in Appendix A. All air pressures except the ttal and static pressures in the test sectin were measured with a 12-in., mercury-filled, manmeter bard and recrded phtgraphically. Hydrgen pressures were measured with transducers and recrded n a recrding ptentimeter. A water-cled prbe was used alternately fr btaining gas samples and ttal pressure measurements in the test sectin. When required, a secnd prbe was used t measure the static pressure. Figure 5 shws prbes with and withut the static tube. The ttal pressure and static pressure were recrded as a functin f psitin (the z tunnel crdinate) n an x-y pltter. A schematic diagram f the ttal pressure, static pressure, and gas sampling system is shwn in Fig. 6. Samples were pumped frm the prbe with a dry diaphragm pump which maintained a pressure f 2 t 3 psi inside the prbe and delivered the samples t the analyzers at slightly abve atmspheric pressure. A water separatr and chemical drier were used in the sampling lines and all analyses were made n a dry basis. Lcal cncentratin f hydrgen in the test sectin was measured by a thermal cnductivity meter described in Ref. 7. Lcal cncentratin f xygen was measured by a meter which detects the change in the magnetic susceptibility f the gas. The xygen meter was calibrated using nitrgen fr a zer and atmspheric xygen fr percent xygen. The xygen and hydrgen cncentratins were recrded n a recrding ptentimeter. An analysis f the mechanism f sampling is discussed in Appendix B. Shck psitin, axial and vertical psitin f the test sectin prbe, and lcatin f emissin frm high temperature znes were determined phtgraphically. The test sectin was phtgraphed with a schlieren camera using either cllimated light frm a spark surce r direct emissin frm the test sectin. The schlieren spark was cllimated t a 6-inch beam by an aerial camera lens. This light and the emissin frm the test sectin were fcused n a 4 in. by 5 in. camera. 3

17 AEDC TDR DATA REDUCTION Pressure data were read frm manmeter bard phtgraphs r x - y recrder charts and reduced manually. Temperature and cmpsitins were btained frm a cmputer slutin f the equatins given in Appendix A. An estimate f the accuracy f the raw and reduced data is als given in Appendix A. 3. RESULTS AND DISCUSSION Shck-induced cmbustin ccurs when a premixed cmbustible mixture is heated t abve its ignitin temperature by passing thrugh a shck wave. The mst familiar example f this is the classical detnatin wave in which a cnstant area bundary cnditin is impsed n the flw. In this case the energy needed t drive the shck wave is supplied by the cmbustin. This is the type f phenmenn seen in a detnatin tube. Here, the final cnditins are determined by the initial cnditins and the applicatin f cnservatin f mass, mmentum, and energy. Previus wrkers with shck-induced cmbustin waves have assumed that the thermdynamics f cnstant area classical detnatins are applicable t all shck-induced cmbustin waves (Refs. 4 and 7). It wuld seem, hwever, that ther aerdynamic prcesses fr releasing heat using shck-induced cmbustin wuld be pssible if different bundary cnditins are applied. It is pssible t describe theretically a cnstant pressure, shck-induced cmbustin wave where the gases heated by the cmbustin expand s that the static pressure in the cmbustin zne is the same as the static pressure behind the shck wave withut cmbustin. Physically this might ccur if a cmbustible cre f gas passing thrugh a shck wave had a relatively small diameter cmpared t the reactin zne length s that the expansin f the heated gases wuld nt appreciably change the static pressure behind the shck wave. It might als ccur in a variable area duct where the cntur exactly matched the rate f heat additin t maintain cnstant static pressure. As lng as the rate f expansin caused by heat additin is lw cmpared t the velcity f the burning gas, there will be negligible radial pressure gradients acrss the cmbustin zne; and, if a step prfile can be assumed, a ne-dimensinal flw apprximatin will describe the flw. As the rati f the diameter t the length f the reactin zne increases, the pressure at the center f the reactin zne appraches the cnstant area value because three-dimensinal expansin will cause sizeable pressure gradients frm the center t the utside f the cmbustin zne. Cnstant pressure shck-induced cmbustin is then limited t cmbustin znes with lng enugh reactin times and slw enugh expansin s that these three-dimensinal effects are negligible. This type f reactin 4

18 AEDC-TDR cannt prduce a nrmal shck wave ahead f it because the same size and reactin rate criteria which allwed the ne-dimensinal apprximatin will preclude the pressure rise necessary t prduce the shck wave. Again the terminal cnditins f the cnstant pressure case can be determined explicitly frm the inlet cnditins and the cntinuity equatins. A mre cmplicated case arises when there is an axial static pressure gradient behind the shck wave. Fr a small diameter cmbustin zne, this pressure can exist independent f the cmbustin. If the cmbustin zne size and the reactin rate are small enugh and step prfiles are assumed, a ne-dimensinal apprximatin will in this case adequately define the flw; hwever, the final cnditins will depend n the velcity at which the heat is added as well as n the inlet cnditins. The terminal cnditins are nt defined by the inlet cnditins and the ttal heat release as they are in the ther cases mentined. In this case the static temperature and therefre the rate f the reactin will be influenced by the pressure gradient. The last case is the mdel which was used fr the analysis f the data frm the SCT. A static pressure gradient exists behind the shck system which depends n the interactin f the shck and expansin waves. The assumptin that this pressure gradient is independent f cmbustin was verified by the data. Ttal pressure lss fr a given amunt f heat release depends n the lcatin in this pressure field where the heat is released. All the pssible bundary cnditins are nt limited t thse mentined thus far, since by applicatin f the prper pressure gradient r area change it wuld be theretically pssible t achieve heat release at cnstant Mach number r cnstant static temperature, althugh these might be impssible t achieve in practice. In an actual cmbustin system, cmbinatins f diffusinal and shck-induced cmbustin may exist, and ne-dimensinal thery wuld nt be adequate. This system wuld be even mre difficult t analyze, althugh ver-all perfrmance may be measurable. 3.1 FLOW FIELD DESCRIPTION i In this sectin are described the aerdynamic and thermal cnditins which exist in the test sectin f the SCT which establish the bundary cnditins fr the cmbustin. This infrmatin is based n ttal pressure and ttal temperature traverses and n a limited amunt f static pressure data. 5

19 AEDC-TDR A general schematic f a Mach reflected nrmal shck system is shwn in Fig. 7. The "nrmal"-shck wave is prduced because the turning angle necessary t straighten the flw behind the first blique shck is greater than the maximum turning angle at this Mach number, s that a simple reflectin cannt ccur. The flw at the shck intersectin is nt turned parallel and cntracts with supersnic flw utside and subsnic flw inside the slip line. Mixing ccurs alng this bundary resulting in the reacceleratin f the center flw bth by cntractin f the flw and by the mixing with higher energy air. The cnfiguratin used fr the nrmal shck studies has been described in the sectin n apparatus and shwn, with the shck system prduced by this cnfiguratin, in Fig Pressure Effects Ahead f the Nrmal Shck Wave In the regin ahead f the nrmal shck wave the air accelerates nearly isentrpically frm the thrat until it passes arund the fuel injectin wedge which causes a reductin in ttal pressure. As a result f wedge interference, the ttal pressure and Mach number prfiles f the air appraching the nrmal shck wave are distrted and have minimum values at the tunnel hrizntal centerline (Fig. 7). A calculatin was made t determine if the discrepancy between the indicated ttal pressures measured at the centerline and the theretical value fr a Mach 3. 1 nrmal shck wave culd be explained. The pressure lss caused by the fuel injectin wedge was cmpared t the mmentum per unit area at the shck wave with the inlet mmentum minus the wedge drag. It was assumed that the dimensinless velcity rati (V - V 1 Ve - V ) Prt resulting frm the wedge drag withut fuel injectin is the same as the dimensinless cncentratin prfile (y/y e) when there was fuel injected (Ref. 8). A turbulent Prandtl number f.5 was assumed. Cnstant static pressure was assumed alng the mixing zne. The mmentum at the shck wave was lip f pv 2 dv per square inch where (Ref. 1) and since fr a given test cnditin at was cnstant (V/at)at y = eve/at - V/at)(Y/Ye):t y + Vjat where Ve/at was calculated frm ~ (experimental) and Pt P (isen, M 3.1 ); 6

20 AEDC TDR Y/at was calculated fr isentrpic M = 3.1; and (y/ye) was the fuel distributin at the same ttal temperature. The mmentum at the fuel injectr was assumed t be the mmentum calculated frm isentrpic relatinships at M = 3.1 minus the wave drag and skin drag n the wedge. The fllwing table cmpares the mmentum at the wedge with that at the shck fr tw ttal temperatures. T t - OR pv 2 /p At the Wedge At the Shck Wave The agreement between the mmentum calculated at the tw statins is clse enugh that the reductin in ttal pressure ver that expected fr a Mach 3. 1 nrmal shck wave can be explained by the mmentum lss n the fuel injectin wedge Pressure Effects Aft f the Nrmal Shck Wave Several pressure prfiles were taken in the regin behind the nrmal shck wave with the preheater n but withut test fuel injectin. Figure 8 shws the data frm an axial static pressure and a pitt ttal pressure traverse. The static pressure at the shck wave was calculated frm the theretical nrmal shck static pressure rise at the centerline; based n the measured indicated ttal pressure and the isentrpic static pressure at a free-stream Mach number f 3. 1, the static pressure falls rapidly frm the shck wave aft and the indicated ttal pressure falls mre slwly. As may be seen frm the data (Fig. 8), the static pressure is almst independent f ttal temperature. This is nt true fr the ttal pressure. As the ttal temperature is increased, the indicated ttal pressure rati increases (Fig. 9). This increase results frm a greater spreading f the wake frm the fuel injectin wedge at higher temperatures [see fuel distributins (Fig. 14)J which spreads the wedge lss ver a greater area and reduces the maximum lss. Pressure prfiles taken in the vertical and hrizntal directin resulted in curves f the type seen in Fig. 1. The hrizntal prfiles are nearly flat in the center. The vertical prfiles are strngly curved indicating bth the disturbance frm the wedge and the transitin in Mach number as the prbe crsses the slip lines frm the shck intersectin. 7

21 AEDC-TDR Frm the static and indicated ttal pressure data, the centerline Mach number and ttal pressure may be calculated. These parameters are pltted in Figs. 8 and 9. The Mach number increases frm the nrmal shck value just behind the shck wave t a supersnic v alue at less than three inches dwnstream f the shck wave (Fig. 8). The Mach number at three inches aft als increases with an increase in ttal temperature (Fig. 9). In SeT when a cmbustible mixture is heated by passing thrugh the nrmal shck wave, it immediately enters a flw field where the velcity is increasing and the static temperature is decreasing. Therefre, any pressure lsses frm cmbustin will depend greatly n the axial psitin at which the cmbustin ccurs. Als, the static temperature drp frm the flw acceleratin will affect the temperature rise frm cmbustin and may greatly change the curse f the reactin Ttal Temperature Prfiles Ttal temperature prfiles were made at varius lcatins in the test sectin. The temperatures were determined frm the analysis f the cmbustin gases frm the hydrgen-fired preheater using 1- percent cmbustin efficiency (see Prcedure). N free hydrgen was ever detected in the test sectin unless test fuel was being intrduced. Typical temperature prfiles may be seen in Fig. 11. The prfiles are relatively flat ver the area f interest at any given axial statin. There is, hwever, a gradual axial drp in temperature tward the rear which results frm mixing f the heated cre with surrunding cler air. As the ttal temperature is increased, the xygen cntent f the air decreases and the water vapr increases. Figure 12 shws the ideal relatinship between the ttal temperature and the gas cmpsitin. This prduces an added cmplicatin since the physical and chemical prperties f the preheater gases are a very cmplicated functin f temperature. Figure 13 shws hw sme f the mre useful f these prperties vary. Fr the preheater gases withut test fuel, Tt is the ttal temperature at the sampling pint. When test fuel is added, Tt is the ttal temperature f the mixture with ( = O. 'l't is the final temperature f the cmbustin prducts at the same lcatin. The additin f cld test fuel changes the temperature and cmpsitin still further. This effect will be discussed in the sectin n cmbustin efficiency. 8

22 AEDC TDR FUEL DISTRIBUTION Fuel injected frm a small hle in the dwnstream side f the fuel injectr wedge (Fig. 3) prceeds dwnstream. While traveling, it mixes with the surrunding air. The rate f mixing is influenced by difference in velcity between fuel and air and by temperature levels. After traveling abut six inches in a Mach 3 flw, the mixture passes thrugh a shck where reactin mayr may nt ccur depending n the gas temperature. Fuel cncentratin was calculated frm analysis f xygen and hydrgen cntent by the methd described in Appendix A. Data with test fuel cmbustin will give the hydrgen equivalence rati (Yl + Y 2 + a 2 ) Since the same preheater level withut test fuel will give Y l' the test fuel will be the difference f the tw calculated equivalence ratis. The resulting fuel cncentratin prfiles were pltted in Fig. 14 and clsely resemble a nrmal distributin curve f the frm K (e) -bz 2, where K and bare cefficients and Z is a tunnel crdinate distance perpendicular t the flw in the~-hrizntal plane. Figure 14 shws a marked increase in rate f mixing f the fuel as preheater temperature is increased. A cmparisn f fuel prfile peaks at the fre and aft psitin in Fig. 14 als shws a decrease in fuel cncentratin with distance frm the nrmal shck. 3.3 COMBUSTION EFFECTS One f the primary purpses f these experiments was t shw that heat release actually ccurred in the area aft f the shck, and, if pssible, t what extent. This was investigated by three methds; temperature measurements, pressure measurements, and radiatin emissin. They will be discussed separately Effect f Temperature n Cmbustin One f the verall bjectives f this study was t determine the rate f reactin f hydrgen-air mixtures. As an initial part f this investigatin, the cmbustin efficiency was measured at varius lcatins in the cmbustin zne. These data are crrelated with psitin relative t the shck wave and with the inlet temperature. An attempt was als made t determine a reactin rate as a functin f the cmbustin mixture temperature Cmbustin Efficiency. The cmbustin efficiency, E, is defined in this reprt as the rati f the test fuel burned t the ttal test 9

23 AEDC- TDR fuel present that culd burn. As was previusly mentined the preheater perates at 1-percent cmbustin efficiency. and the preheater hydrgen is nt cunted in calculating the test fuel cmbustin efficiency. Accuracy with which the efficiency and temperature can be measured depends n tw factrs: (1) the accuracy with which the cmpsitin f the sampled gas can be determined (see Appendix A) and (2) the rate at which the reactin is quenched as it enters the prbe. The rate f quench is discussed in greater length in Appendix B. Hwever. it shuld be nted that free radical recmbinatins cannt be quenched; that is. any OH. H. r will recmbine t frm H2. H2. and 2. Any energy released during these recmbinatins will increase the temperature f the gas after it has entered the prbe. The recmbinatins can be ignred if the efficiency is cnsidered as the hydrgen cnsumed. Calculated temperatures and energy release will be higher than the free-stream values by the dissciatin energy f the free radicals present. even if it is assumed that the dissciatin and branching reactins are cmpletely quenched. The relatinship between! three inches dwnstream f the nrmal shck and ttal temperature ('l\j is shwn in Fig. 15. Figures 15a. b. and c shw hw (: varies alng the hrizntal centerline fr several inlet temperatures. The gas temperature frm the preheater is nearly unifrm alng the hrizntal centerline when n test fuel is added; but in calculating a crrectin fr the cld test fuel it was fund that there is a reductin in ttal temperature which is prprtinal t the ttal test fuel added. Figure 16 shws as a functin f ttal temperature (Tt ) crrected fr the cling effect f the hydrgen at an axial psitin three inches aft f the nrmal shck wave. At this statin fr a plenum ttal pressure f 5 psia the efficiency is. within the experimental errr. a functin f inlet ttal temperature nly, with n nticeable effect f fuel cncentratin. The static temperature f the gas just behind the shck wave may be calculated by multiplying Tt' crrected fr the ttal temperature rise alng the axis (Fig. llc), by the static t ttal temperature rati at the shck wave (Frm M in Fig. 8). A resulting inlet static temperature f abut 23 R is required t prduce 5-percent cmbustin efficiency in three inches and abut 195 R t prduce five-percent cmbustin in the same distance. In a system such as this where the flw accelerates rapidly behind the shck wave, the cmbustin efficiency rises rapidly at first, and then as the static temperature reaches a maximum, its rate f rise decreases (Fig. 17). The static temperature rises rapidly at first because the ttal temperature is increasing. HweVer, at the same time the static t ttal, temperature rati is decreasing because f the flw acceleratin. As the 1

24 AEDC. TDR reactin nears cmpletin this effect becmes predminant, and the static temperature begins t decrease. Since the static temperature was calculated frm Mach number and ttal temperature, the accuracy f this parameter depends n the accuracy f bth the ttal temperature and the indicated static and ttal pressure measurements Reactin Kinetics. The relatin between cmbustin efficiency and distance can be transfrmed t a relatinship between cmbustin efficiency and time by calculating the velcity-distance relatinship frm experimental values f P s ' Pt', and T t and graphically integrating x l/v vs X where f l/v dx "" r (X) Figure 18 shws the ( pltted as a functin f r. The slpe f this curve is d 1'/ d r which equals _ 1 d (H 2 ) (H 2 ) t d r A glbal equatin fr the rate f cnsumptin f hydrgen can be written as: where A is a cnstant, E is the glbal activatin energy, and m and n are cnstants which determine the verall rder f the reactin. If the prper values fr m and n are knwn and ne relatinship will describe the whle reactin, a plt f lg A e E/RT vs lit will be a straight line, where the slpe is E/R and the intercept at E/RT = 1 is A (Fig. 19). The data shwn in this figure came frm tw runs at different inlet temperatures. The activatin energies, as represented by the slpe f the curves, were calculated frm the tw sets f data and are nearly the same abve a static temperature f 28 R. The change in slpe belw 28 R culd result because the glbal equatin, as written, des nt describe the reactin ver a brad temperature range r because f errrs in the data at the lwer temperature. The difference in the intercepts f the tw curves als shws that the equatin des nt describe the reactin cmpletely. The calculated activatin energy is clse t that fr the reactin H2 + - OH + H which has been prpsed as the rate cntrlling step in the hydrgen-xygen cmbustin (Ref. 4). Hwever, there are an insufficient number f data pints t establish a definite value fr the cnstants in a glbal equatin. Between O. 5 in. and 3 in. aft f the shck wave, the change in cmbustin efficiency is very small (Fig. 17). Reactin rates in this range are much lwer and d nt fit the same glbal equatin as they d in the early part f the reactin. It is pssible that the rate f change f hydrgen cncentratin is affected by mixing r that an apparent change results frm a failure f the prbe t fllw a streamline. 11

25 AEDC-TDR Effect f Temperature Rise n Ttal Pressure As a further attempt t verify heat release, ttal pressure was measured at varius inlet ttal temperature levels and lcatins in the zne f interest dwnstream f the nrmal shck, bth with and withut test fuel. Als, a simplified theretical crrelatin f this data was attempted. Fr the case f n frictin, mass additin, r mlecular weight change (Ref. 6), the fllwing relatin may be written between ttal pressure and ttal temperature which, when integrated fr the cnditin f cnstant Mach number and y, becmes (1) (2) Althugh ttal pressure rati is a functin nt nly f ttal temperature rati, but als f Mach number and y, Eq. (2) may be used fr a practical case where ttal temperature increases are small, and y, Mach number, mass, and mlecular weight changes may be cnsidered t be insignificant. With this equatin in mind, the data n pressure measurement will be examined. First, Fig. 15 shws there are tw pressure prfile curves fr each inlet gas temperature level (Tt )' ne fr the cnditin f preheater nly and the ther fr preheater plus test fuel. Nte als that the difference between the tw curves increases with increased inlet temperature level. Here a ttal pressure lss is apparent when cmbustin ccurs; hwever, ttal pressure lss may result frm reduced mlecular weight als. Then in Fig. 2, the ttal pressure drp caused by unburned fuel is shwn, and in Fig. 21 the effect f cmbustin is demnstrated by adding in a large grup f data at varius degrees f reactin cmpletin. Nw a family f lines can be drawn, shwing the relatin between heat release, fuel cncentratin, and ttal pressure lss. If the effect f pressure drp caused by unburned fuel is remved by using the data f Fig. 2, the curve f Fig. 22 may be drawn. Thus far, nly experimental data have been discussed, and it can be seen that the scattering f these results are well within the estimated experimental accuracy, as defined in Appendix A. In calculating the pints fr these curves, it was necessary t use ttal and static pressure measurements and ttal temperature, y, and mlecular weight frm the gas analysis. 12

26 AEDC-TDR Nw, the questin arises, can the measurement f ttal pressure nly be used t predict the quantity f heat release. The answer is n because enugh additinal infrmatin must be knwn t describe the prperties f the flwing gas, such as Mach number, y, and mlecular weight. Hwever, enugh experimental infrmatin was btained s that the pressure drp caused by heat additin culd be separated frm that caused by fuel, and with what is cnsidered gd agreement. Equatin (2) was used with a stepwise calculatin. Temperature increments f 1 R were used. The initial Mach number cnditins were calculated just aft f the nrmal shck, based n the plenum and test sectin pressures, analysis f the wedge effect n the flw (Sectin ), and the fuel cncentratin. The axial static pressure prfile was experimentally fund t be independent f heat release at distances greater than ne inch aft f the nrmal shck wave. Just behind the shck wave the static pressure was calculated frm the free-stream static pressure at Mach 3. 1 and the measured ttal pressure. Using this value and the experimental data, the pressure distributin curve f Fig. 23 is shwn. The specific heat rati (y) was calculated frm the gas analysis and temperature determined frm the gas analysis. Thus, an incremental ttal pressure drp was calculated, resulting in a new ttal pressure fr the next increment. In this manner, the calculatin was cntinued until the temperature rise tapered ff t zer at a distance abut O. 6 in. dwnstream f the shck. A cmparisn between the calculated ttal pressure lss and the experimental data, fr the cnditin f test fuel injected and preheater n, is given in Fig. 24 at tw different inlet temperatures. This crrelatin is cnsidered gd because a Mach numb~r errr f.5 used in the stepwise calculatin wuld result in an errr f abut.2 percent per step and an verall errr f abut 3 percent. The uncertainties in the static pressure measurement culd easily cause this difference. These experimental pressure data were crrected fr unburned fuel. It was assumed that the difference between the fuel-n and fuel-ff ttal pressure just aft f the nrmal shck (X '" ) was caused by the presence f unburned fuel, and that as the fuel burned, this effect was reduced prprtinally t the cncentratin f fuel. Althugh water vapr was present, its verall effect was small cmpared t that f hydrgen, and therefre it was neglected. The resulting equatins are: (~)p - (~)Pf (;~~) P X = Pressure lss rati caused by fuel just aft f the nrmal shck (3) 13

27 AEDC TDR and [ ( y 2 + a 2 ) - y 2 fj X (y 2 + a 2 ) (4) s that [,,-,, ] ~ meas 1 -[~P:tLJ t p X (5) The terms in the preceding equatins are lcated n the fllwing schematic diagram: G:p) Preheater Only ( ~p::f) Prebeater + Burning Fuel - x Distance Frm Shck... The crrelatin was calculated nly t abut.6 in. aft f the nrmal shck since (1) mst f the temperature rise ccurs within this distance and 14

28 AEDC-TDR (2) it was surmised that mixing lsses were becming prnunced at this pint, which wuld have made further calculatins irrelevant since the equatins used did nt accunt fr mixing. Frm the freging data and analysis, these cnclusins may be stated: 1. There is a well defined pressure lss effect that can be attributed t (1) fuel injectin lsses when hydrgen is added and t (2) heat additin frm cmbustin. 2. This effect may be crrelated with simple thery, even thugh the flw field is changing, if sufficient infrmatin n the flw field is at hand Test Sectin Emissin During the investigatin f hydrgen cmbustin initiated by a shck wave, prnunced emissin was visible in the regin behind the shck wave Nrmal Shck Wave. An emissin phtgraph dwnstream f a nrmal shck wave was superimpsed n a schlieren phtgraph and is shwn in Fig. 25. This type f emissin has been used t calculate an ignitin delay time (Refs. 1, 2, and 4). Hwever, in the SeT, althugh emissin frm the test sectin begins at an inlet ttal temperature f abut 17 R, the cmbustin efficiency des nt exceed five percent unless the ttal temperature is abve 2"R. In an attempt t determine the surce f this radiatin, a spectrgram (cvering a wavelength frm abut 3 t 6 A) was taken f the brightest part f the emissin zne. A quartz prism spectrphtmeter with a phtmultiplier detectr was used. The nly radiatin which culd be detected was emitted arund 35 A which crrespnds t the band head f the, OH band at 364 A, and cntinu~us radiatin which, when analyzed, had the spectral distributin f a black bdy at 34R. The mst lgical explanatin fr the cntinuus radiatin is that it cmes frm particulate matter in the stream. This is nt t say that the particles are at 34 R, since the emissivity f small particles will vary with wavelength and the relatinship between true temperature and apparent black bdy temperature is quite cmplicated. The particles apparently were heated by the hydrgen cmbustin, since at inlet ttal temperatures up t 28 R there is n glw withut hydrgen. Abve 28 R there is an verall glw in the test sectin which becmes brighter as the temperature is increased and which is brighter behind the shck waves 15

29 AEDC TDR where the static temperature is higher (Fig. 26). The fact that the lcatin where the emissin brightens is cincidental with the lcatin f the shck waves wuld imply that at least sme f the particles are very small «< 1 micrn) since they must be heated appreciably in less than ne micrsecnd. Any lnger delay than this culd be detected as a gap between the shck waves as shwn by the schlieren system and the shck waves as utlined by the emissin increase. Other particles must be substantially larger since there is emissin ahead f the shck wave where the static temperature is abut 1 R, and the particles radiating here must have retained their heat frm the preheater. Within the limits f knwledge f the temperatures f the particles, a particle size distributin frm 1 t O. 1 micrn wuld prbably satisfy these cnditins. Gas stream analysis has shwn small quantities f irn and aluminum xides t be present in the supply air. This cntaminatin prbably riginates frm scale in the pipe and frm the aluminum xide air drier and culd accunt fr the bserved effect. It is pssible that the emissin which is seen culd result frm surface reactins which heat the particles withut appreciably changing the gas temperature r the cmpsitin f the bulk f the stream. It is nt knwn whether particles heated by surface reactins wuld affect the verall rate f the reactin, but it is pssible that these reactins culd cause an increase in the cncentratin f free radicals which culd change the rate f the branching reactins. Als later in the reactin, the particles culd prvide a surface fr recmbinatin reactins. Bth f these effects wuld cause an increase in the verall rate f cnversin f hydrgen and xygen t water vapr Oblique Shck Wave. The emissin seen behind the shck wave when a nrmal shck cnfiguratin was used was als seen with the blique shck wave cnfiguratin, Figure 27 shws emissin phtgraphs f the test sectin at an inlet ttal temperature f ver 3 R with nitrgen and then with hydrgen flwing thrugh the fuel injectr. Bth phtgraphs were prcessed in the same manner and shw the relative intensity and lcatin f the emissin frm the ht preheater gases and frm the hydrgen reactin. The calculated static temperature immediately behind the blique wave is the same as that behind a nrmal shck wave with a ttal inlet temperature f abut 23 R. Under these cnditins a reactin shuld prceed in the main bdy f the gas n the rder f 4 percent f the hydrgen burned in the first inch behind the blique shck Wave. This cnclusin is based n the effect f inlet temperature n cmbustin efficiency (Fig. 16) and n the spacial distributin f the cmbustin zne (Fig. 17). Several attempts were made t determine if there were a Mach number change resulting frm heat additin behind an blique wave by lking 16

30 AEDC- TDR fr wave angle increases n small wedges munted in the emissin zne. Results f the data were incnclusive because f (1) aerdynamic effects which prevented the shck waves frm being straight and clear-cut and (2) reduced density at high temperature which reduced the visible shck wave intensity as seen in the schlieren system. N data n cmpsitin changes were btained because the gas sampling system was nt in use at the time. 4. CONCLUDING REMARKS A series f tests were cnducted in the Supersnic Cmbustin Tunnel t determine the efficiency f the cmbustin in a shck-induced cmbustin wave, the effect f the cmbustible mixture temperature n the cmbustin efficiency, and the relatinship between the ttal pressure lss and the amunt f heat release. An aerdynamic analysis f the Mach reflected nrmal shck system shwed a static pressure gradient behind the nrmal shck wave which caused the flw t be re-accelerated t abut Mach 1. 6 three inches dwnstream f the nrmal wave. This pressure gradient was independent f ttal temperature level and was unaffected by the presence f cmbustin behind the shck wave. Hydrgen fr shck-induced cmbustin was intrduced frm the center f a wedge-shaped strut lcated in the supersnic flw abut six inches upstream f the nrmal shck wave. The fuel spread s that the entire height f the nrmal shck wave cntained a cmbustible mixture. This spreading increased further dwnstream and als increased as the ttal temperature was raised. When test fuel was intrduced, the cmbustin efficiency rse rapidly at first and then at a lwer rate. The decrease in rate resulted frm a reductin in the quantity f hydrgen available t, burn and frm the reductin in static temperature caused by the expansin f the gas. Three inches dwnstream f the shck wave the cmbustin efficiency was a functin f inlet ttal temperature and independent f the initial hydrgen cncentratin within the experimental accuracy f the data. Initial cmbustin ccurred at a ttal temperature f abut 18 R, increased t 5 percent at abut 23 R and t 9 percent at abut 3 R. The effect f temperature rise n ttal pressure lss was measured fr several cnditins f inlet temperature (Tt ) and psitin dwnstream f the nrmal shck and was crrelated with fuel cncentratin and cmbustin efficiency. In additin, a crrelatin f pressure lss and 17

31 A E DC TD R temperature rise was btained by calculating the pressure lss fr an incremental temperature rise with a simplified equatin and, using the knwn factrs abut the flw field, then cmparing the resulting values with the experimental data. Crrelatin between the calculated and experimental values was shwn in the regin just aft f the nrmal shck where the temperature rise ccurred. Emissin frm the cmbustin zne was detected at inlet ttal temperatures as lw as 17R and increased in brightness as the temperature was raised. Spectral analysis shwed this emissin t cnsist f sme radiatin abut the wavelength f the OH band emissin and cntinuus radiatin which increased frm shrt t lng wavelengths. It is pssible that the cntinuus emissin came frm particles f irn and aluminum xides heated t incandescence by surface chemical reactins. Tests were made with a single wedge in an attempt t get blique shck-induced cmbustin. Emissin was seen behind the shck wave, but since n chemical analysis f the gas was taken behind the shck wave n quantitative evidence f cmbustin was btained. REFERENCES 1. Jamisn, R. R. "Hypersnic Air Breathing Engines." Brist1- Sidde1ey Engines, Ltd., Paper prepared fr Clstn Sympsium, Bristl, Weber, R. J. and MacKay, J. S. "An Analysis f Ram Jet Engines Using Supersnic Cmbustin." NACA TN 4386, September Dugger, G. L. "A Future fr Hypersnic Ramjets." Astrnautics, April Nichlls, J. A. "Stabilizatin f Gaseus Detnatin Waves with Emphasis n the Ignitin Time Delay Zne. II AFOSR TN 6-442, June Nichlls, J. A., et. al. "On Experimental and Theretical Study f Statinary Gaseus Detnatin Waves." AFOSR-1764, Octber Grss, R. A. "Explratry Studies f Cmbustin in Supersnic Flw." AFOSR TN , June Rhdes, R. P. and Chriss, D. E. "A Preliminary Study f Statinary Shck-Induced Cmbustin with Hydrgen-Air Mixtures. " AEDC-TN-61-36, July

32 AEDC-TDR "Turbulent Flws and Heat Transfer." Princetn University Press, 1959, pp Shapir, A. H. "Dynamics and Thermdynamics f Cmpressible Flw, Vl. 1." Rnald Press, Ames Research Staff. "Equatins, Tables, and Charts fr Cmpressible Fluid Flw." NACA Reprt 1135, Lewis Labratry Cmputing Staff. "Tables f Varius Mach Number Functins frm t " NACA TN 3981, April Thrasher, L. W. and Binder, R. C. "A Practical Applicatin f Uncertain Calculatins t Measured Data." AS ME Paper N. 55-A- 25, Keenan, J. H. and Kaye, J. Gas Tables. Jhn Wiley and Sns, Handbk f Chemistry and Physics, 34th Editin. 1952, pp. 1613, Chemical Rubber Publishing C. 15. German, R. C. and Bauer, R. C. "Effects f Diffuser Length n the Perfrmance f Ejectrs withut Induced Flw. " AEDC-TN , August

33

34 AEDC-TDR APPENDIX A CALCULATION PROCEDURES CHEMICAL REACTIONS The chemical reactins f interest are lcated physically in tw places: in the preheater where 146 R air is heated t a higher temperature by cmbustin f hydrgen and in the test sectin where fuel is injected and reactin phenmena are bserved. Since all data t date indicate n residual hydrgen frm the preheater reactin, cmbustin efficiency there was cnsidered t be 1 percent. Cmbustin efficiency in the test zne is based n the rati f fuel quantity that has disappeared in a reactin prcess as cmpared t the ttal fuel that culd theretically react. Hence, if the fuel cncentratin is greater than stichimetric (equivalence rati> 1), the quantity f fuel in excess f stichimetric is autmatically excluded frm the efficiency calculatin. In rder t accmplish this calculatin, it was fund necessary t calculate verall cmbustin efficiency f preheater and test fuel, insert the knwn value f preheater fuel cncentratin at 1 percent cmbustin efficiency, then calculate the resulting cmbustin efficiency f the test fuel. The equilibrium reactin equatin f H2 - air after quenching and cling, fr varius efficiencies, is as fllws; (A-1) where 'rf (verall cmbustin efficiency) is defined as: TJ = amunt f fuel burned amunt f fuel that culd be burned with available 2 = cmbustin efficiency fr test zne fuel Y 1 = equivalence rati f fuel frm preheater Y 2 = equivalence rati f test fuel a 2 = equivalence rati f test fuel greater than E.R

35 AE DC TDR The cmpletely burned gas frm the preheater may be analyzed and equivalence rati (E./{.) calculated frm Eq. (2) where H2 % = and Tf = 1 %: (A-2) where (2) = percent f xygen in the gas by vlume, n a dry basis Once Yl is established at a fixed preheater level, test fuel can be injected. Since test fuel can exist frm t 1 percent burned, bth xygen and hydrgen analyses are required t determine degree f the reactin cmpletin. Here, it is assumed that the reactin is quenched a shrt interval f time after entering the sampling prbe (see Appendix B), and that free radicals have recmbined with their prper assciates during the cling prcess. With these assumptins, the fllwing equatin may be btained frm Eq. (A-1): (Y 1 + Y 2 + a 2 ) = ( 2 ) +.88 (H 2 ) 1 - [ (H.) + ( 2 ) 1 (A-3) where (H2 ) = percent f hydrgen by vlume, dry. Since Y 1 is nt knwn, (Y 2 + a 2 ) may be calculated. Since a2 can be greater than zer nly if (Y 1 + Y 2 + a 2 ) > 1, then a 2 and Y 2 may be evaluated. Frm Eq. (A -1) may als be derived the equatin fr Tf: ( 2 ) - (H 2 ) (A-4) Cmbustin efficiency fr the test fuel nly may then be defined as: (A-5) GAS TEMPERATURE CALCULATIOH In calculating gas temperature, dissciatin was assumed t be negligible. Since dissciatin is nt appreciable until temperatures abve 4R and near r abve stichimetric ratis are reached, it was neglected fr the data f this reprt. 22

36 AEDC TDR The final gas temperature was btained frm the fllwing equatins: Enthalpy Balance ( mfr2 hh2 + mf h2 + mfn hn 2 + mfr hh 2) ~ pr",ucts (A-6) On the basis f ne mle f O 2 prducts are: Reactants the mle functin f the reactants and Prducts mfra 2 (Y 1 + Y2 + a 2) mf R2 2(Yl+y 2 )(l -Tf)+2a2 mfair 4.77 mf (Y 1 + Y2) Tf m fn2 == 3.77 mfra O 2Tf (Y 1 + Y 2 ) Enthalpy equatins fr the prducts in the frm h == a + btt + ett 2 were develped fr 1i 2, O2, N2, and H 2 frm 12 t 4R using enthalpy data frm Ref. 13: hh2 == T t x 1-3 T/ Btu/lb mle (± 1)* (A-7) h T t x 1-3 Tt~ Btu/lb mle (± 3) (A-B) hn T t x 1-3 T t 2 Btu/lb mle (± 4) (A-9) hh 2 == T t x 1-3 T t 2 Btu/lb mle (± 6) (A-1) In these equatins, h == at 524 R. Similar equatins fr the reactants were develped: TtR (± 1) * 2 (A-ll) hair T tair (± 2) (A-12) where h == at 524 R and Q R == 141 Btu/lb mle at 524 R. (Ref. 14) *The equatin fits the tables (Ref. 13) t this tlerance expressed as Btu/lb mle. 23

37 A E D C. TD R These equatins may be cmbined t frm the quadratic equatin: [ CY l + Y 2 + a 2 ) " CY l + Y 2 )] 1-3 T t 2 + [ CY l + Y 2 + a 2 ) ",CY l + Y 2 )] T t (A-13) - [ CY l + Y 2 + a 2 ) " CY l + Y 2 ) These equatins fr a H2 - air reactin mixture are accurate t ±5 R. Three gas temperatures may be calculated: 1. Preheater nly CTt ) where Y 2 and a 2 are and." "" Preheater plus test fuel withut test fuel cmbustin {T t ) where ",CYl + Y 2 ) = Yl' 3. Preheater plus test fuel with test fuel cmbustin C T t ) as written in Eq. (A-13). Thus, the prperties f the reacting gas that can be determined frm a H2 - O 2 analysis n a dry basis, assuming a quenched reactin, are as fllws: 1. Fuel-air rati (partially burned r unburned). 2. Cmbustin efficiency. 3. Gas temperature frm fuel-air rati and cmbustin efficiency. ERROR ANALYSIS Errr analysis was based n an estimated 95-percent prbability that the measurements lay inside a certain interval. Fr measured data, the interval was taken as that within which repeatable bservatins culd be made. Fr calculatins the plus r minus increment C ~) was calculated frm the data L\'s. A cmparisn f Table A-1 with Figs. 16, 19, 2, and 21 will verify the validity f the estimated 95-percent prbability. Table A - 1 was based n f values near 3 percent, abut mid range. 24

38 AEDC-TDR TABLE A-l PARAMETER REFERRED 95 - PERCENT SOURCE CONFIDENCE LIMIT Pt' (P.R. & Fuel) Data ±.6 % Pt' (P.R. Only) Data ±.6 (Pt' P.R. & Fuel) / (Pt' P.R. Only) pt'data ± 1.2 Ra Data ± 1.6 O 2 Data ±.8 Yl R 2, O Y 1 + Ya RaJ O 2, Yl +7." R 2, O 2 +6 f.", Y 1 ' Y 2 +9 Tt Y1 +2 T t Y 1 (Yl + y 2 h +5 Tt/Tt Tt ' T t Reliability f the R2 and O 2 analysis may be gaged by pltting fuelair equivalence rati fr unburned fuel as calculated by Eqs. (A-3) and (A-4). A plt f this nature is shwn in Fig. A-l. An errr r deviatin f bth measurements can cancel ut r cause dispersin f data frm the "perfect agreement" line. 25

39

40 AEDC TDR in. test sectin 3 in. test sectin 1.2 T t = 14 R Vl Vl >. r c P t = 4 psia l. «4.77 (H ) 2 c OJ Y2 = "> H2 I- "' >. 2 [1 - (H 2 )] (2) ::c E Y2 = I , r :::: OJ u c OJ r > :::J - w N > (2) ~------~------~----~------~------~----~ Y2 Equivalence Rati frm Oxygen Analysis Fig. A.l Crrelatin f Fuel Cncentratin frm Hydrgen and Oxygen Analysis 27

41

42 AEDC-TDR APPENDIX B ANALYSIS OF CHEMICAL REACTION QUENCH RATES IN THE GAS SAMPLING PROBE Since much f the data and cnclusins in this reprt are based n sampling f the gas in a burning stream, the questin arises as t just hw rapidly quenching f the chemical reactin ccurs. That quenching ccurs is well established by the fact that cmbustin efficiencies, calculated based n the gas analysis, ranged frm zer percent t apprximately 9 percent. The reactin is started if any cmbustin can be detected. The calculated cmbustin efficiency indicates that the gas entered the prbe (Fig. B-1) at sme state f reactin cmpletin, and was quenched inside the prbe between the inlet rifice and a pint dwnstream, based n the fllwing analysis: a. When the prbe was psitined in the supersnic flw ahead f the nrmal shck r just aft f the nrmal shck where n emissin was bserved, the calculated cmbustin efficiency was zer. This was fund t be true even thugh the calculated cmbustin efficiency ne inch dwnstream was as high as 6 t 7 percent. This bservatin indicates that quenching ccurred faster than the reactin culd achieve a measurable start, r less than 3 micrsecnds (Fig. 1b). b. When a straight tube prbe inlet was used instead f the chked rifice f Fig. B-1, n quench ccurred at all, and the reactin prceeded t cmpletin inside the prbe. c. Analysis f the prbe interir flw after the gas had entered indicates that the flw is chked and expands supersnically. The tw pssible cases are: 1. Separated flw (as shwn in Fig. B-1) where the gas expands t abut M = 1. 7 r higher and dissipates int the surrunding cler gas. (Expansin. and quenching ccurs in less than 1 micrsecnd. The flw is abut 85 percent diffused int the surrunding cl gases in 3 micrsecnds.) 2. Fully develped expansin, which is pssible with the 6 t 7: 1 pres sure rati available. (In this case, the flw expands t Mach 3.5, and the reactin is quenched in less than 1 micrsecnd. This flw shcks dwn in abut 5 diameters (Ref. 15). The changes in static temperature when passing the quenched gas thrugh the shcks are nt 29

43 AEDC-TDR clear. Here again, if re-ignitin did ccur, it is expected that its presence wuld becme knwn in the gas analysis. ) The cnclusin reached frm this analysis is that quenching f the reactin must ccur within a perid f 2 t 3 micrsecnds. 3

44 HEAT TRANSFER STAINLESS STEEL GAS INLET.2 in. DIIAM-p t "15 psia / r-shock PRESE NT ;/B/; :::!li;::.--- / IN SUPERSONIC ((III:'/'/(:--;,~===--=====-_- ZONE ONLY "--:~~; ~ Ps =2-3 psia-\/ WATER FLOW W I-' FLOW "'~~~- MIXING AND T, = 3. R \ ~2't':(: t-cooling ZONE.6 in. DIAM... / t SUPERSONIC FLOW COPPER WALL J ~~~ ~~ 1/ f /' I --;: ~ ~ ( \ \ I '",,, \... (... ~ (~_ ~========- \~ ~ '- --==----~ -- ~r:-_ - IFig. B-1 Schematic f Gas Sampling Prbe Quench Analysis > m () I -I :: I - J«.). '.J

45

46 AEDC-TDR I DIFFUSER itest SECTIO~ NOZZLE I PLENUM ~ I r I ~ r48i DISCHARGE TO PLANT EXHAUST-4...> I ~~4:"~ -~== SYSTEM 1.1. INLET 5 TO TEST FUEL INJECTION WEDGE 15 R AT 4 TO 5 PSIA PREHEATER FUEL INLET EXIT FROM PREHEATER, MAX 35 R ALL DIMENSIONS IN INCHES Fig. 1 Supersnic Cmbustin Tunnel with Nrmal Shck Cnfiguratin 33

47 » m n. -I ;:. - ~ '-l ex> ~ 1. SCALE: INCHES (SCHLIEREN WINDOW w fi::. r FUEL.d.. INJECTOR r---total PRESSURE AND SAMPLING PROBE WEDGE SUPPORT Fig.2 Schematic f Nzzle and Test Sectin Shwing Nrmal Shck Cnfiguratin with Schlieren Pht f Shck System

48 AEDC-TDR c '';: U G/ 'r: G/ ~ u. M g\ u. 35

49 AEDC.TDR Fig.4 Single Wedge Used t Prduce Oblique Shck Waves 36

50 AEDC.TDR <>fli-1/2 in. TWO.4 in. DIAM STATIC PRESSURE TAPS.125 in. DIAM STAINLESS STEEL TUBE 2.in.... L_.38 in. DIAM STAINLESS STEEL TUBE COOLING WATER--.l EXIT.1 in. DIAM--.// STAINLESS STEEL TUBE DETAIL -{).25 in. DIAM STA!NLESS STEEL TUBE.125 in. DIAM COPPER TUBE l-2in DIAM HOLE.5in. Fig.5 Pressure and Sampling Prbe )' DETAIL '" 37

51 TRANSDUCERS REFERENCE PRESSURE r - -I X-Y PLOTTER I» m n. -I ;;:. - "" ~ c RECORDING POTENTIOMETE R!J.:I STATIC- PRESSURE "-TOTAL PRESSURE AND GAS SAMPLE I B I 2 t PAJS DETECTOR t jj H2 DETECTOR H2 REFERENCE TANK FLOW GAS DRYING TUBE Fig. 6 Schematic f Pressure and Gas Sampling Equipment -----

52 w CD HEIGHT OF DISTUR BED FLOW FROM THE FUEL INJECTOR - - AIR FLOW - - / - TOTAL PROFIL:RESSURE FUEL/ CONCENTRATION PROFILE :N~R-;AL';-~ SLIP LINE CONVERGES [FROM SHOCK SHOCK INTERSECTION AND WAVE DEGENERATES TO A MIXING BOUNDARY hili OBLIQUE SHOCK ~ WAVE -- - Fig.7 Mach Reflected Nrmal Shck Wave > m r --I ;;.. - IV '" ex>

53 fl::: ~ pip calculated frm p and Pt'.24 J- / t t'.22 J-.2 ~" ".18 ""-... Cl.. " Cl.. Calculated pint "" ;..,~ ~ 4t"Pt ' experimen; v,... -l 1. 8 " "- -c "- c "" CQ.14 ~ -l 1. 4 Cl.. LMach number, calculated! Q) -... Cl....c frm p and Pt' E ~ Cl z: p /Pt ' experimental.c u.8 Test Sectin Width - 3 in. CQ :;E Prbe Psitin ~./ -- Y=O -l.6 Z=O ta (at shck).4 ~ -- Test Cnditins 146 cpr Test Fuel Off cpr ~ -l.2 Pta = 52 psia " ::::l > m (). -I ;:. - ~ ~ X, Distance frm Shck, In. Fig. 8 Variatin f Flw Parameters n Tunnel Centerline

54 .." ' -- a::: c Q.) "- ::J V) V) Q.) "- a... c -- I- "'C Q.) -- c U "'C C _~---- ~O~ Test Sectin Width - 3 in. Prbe Psitin X = 3. Y= Z= Test Cnditins Test Fuel Off Pt = 5 psia p 1Pt =.55 "- Q.)..Cl E :::J Z..c u c 2: t-,...- -~ Ttal Temperature, Tt ' R Fig. 9 Effect f Preheater Temperature n Flw Parameters ~n Tunnel Centerline 44» m -I AI. a- t:-' "

55 ..., , ~.32 N I, Vertical height f nrmal shck --IY" 'I' -lr 6. 6.~ Vertical Traverse Test Sectin Width - 3 in. Prbe Psitin X =.22 Z=O Test Cnditins Test Fuel Off P t = 5 psia T t = 23 R t::,. Hrizntal Traverse Test Sectin Width - 3 in. Prbe Psitin X =.74 Y=O Test Cnditins Test Fuel Off Pt = 5 psia T = 23 R t.6.8 l. > m. (). -i ; - t;->... (X) Y r Z. In. Fig. 1 Ttal Pressure Prfile Aft f Nrmal Shck Wave

56 AEDC-TDR p----<) Test Sectin Width - 3 in. Prbe Psitin X = 3. Y=O Test Cnditins Test Fuel Off P = 5 psia t 28 f- I ::: 26 f--... I- ~ '- '-" Q.) l... :::J r... l... Q.) Cl.. E Q.) I- 24 ~-- /\ A -v A r... Q I- 22 f-- I 2 h(} f- A ~ 18 f- Tunnel Centerline I I I I Z Distance frm Centerline, In. a. Hrizntal Fig. 11 Ttal Temperature Traverse - N Test Fuel 43

57 A E D C TD R :: ~.=- Q)~ ~ ::::l +-' ftj ~ Cl) " E G.l I r- - Test Sectin Width - 3 in. Prbe Psitin X =.2 Z=O Test Cnditins Test Fuel Off P t = 5 psia - rt~ +-.' ~ 2 I- 18 r I -.2 I I I Y Distance frm Center line, In. b. Vertical Fig. 11 Cntinued 44

58 fl::>. tjl :::... ~ w!-. :::J... C'O!- W... E w ~ C'O... ~ 3. Test Sectin Widtll - 3 in. Prbe Psitin Y= 28 Z= Test Cnditins Test Fuel Off P t = 5 psia '- ---I... --'- ---L L.- "--- ""'"--_-' X Distance Aft f Shck, In. c. Axial Fig. 11 Cncluded» m ().. -I ;; - '" ~ >

59 A E DC. TD R c... u r I... w... Q) :2: c O. 16 O. 14 O. 12 Vl O.lD. E u Preheater inlet temperature, 146 R T frm Preheater, R t Fig. 12 Preheater Gas Cmpsitin vs Ttal Temperature 46

60 AEDC TDR l.1 L <C.....c: VI Q) 1. 8 'w 5: ~ L VI 1.6 cu cu (!) VI Q) ~ ~ 1. 2 Mles gas/mles air 1. O'l :::J U Q) Speed f sund, at Specific heat rati, y ~ >--... '+~ :.;::; cu :::... cu Q) cu+-- u Q) -~ 24 ::J: Vl U :.;::: ' u - Q) Q).. Q) Vl 22 8; Preheater inlet temperature, 146 R T t frm Preheater, R Fig. 13 Preheater Gas Prperties vs Ttal Temperature 47

61 A ED C- TD R ~ ~~ ~ Frward Psitin 1. 2 Test Sectin Width - 3 in. 1.1 Prbe Psitin X = Y = O. 9.8 O \ \ \ Test Cnditins Pta = 5 psia \ \ \ \, T ta, R.~.3 :::J, C'" LLJ.2, c r! C Cl,) U C U Ql O. 9.8 O O. 2 O R R ""- '" ~~~= ~~ '~-~ Aft Psitin Test Sectin Width - 3 in. Prbe Psitin X=3. Y=O Test Cnditins Pta = 5 psia T ta, R <> 171R 186R <) 24R O~~--~~~--~~--~~---~~--b-~~~ O. 7 O. 6 O. 5 O. 4 O. 3 O. 2 O. 1 O. 1 O. 2 O. 3 O. 4 O. 5 O. 6 O. 7 Distance frm Hrizntal ~, Z Directin, In Fig. 14 Fuel Distributin as a Functin f rt 48

62 AEDC TDR J.. - c -+J I I Test Sectin Width - 3 in. f- I Prbe Psitin.23 f- X = 2.8 Y=O.22 r O. 17 Test Cnditins I- p lip n test fuell Pt = 5 psia t t f- ~~... ~ - 'O,~-~-~~~ [ - Test fuel n - 1. N lj) >. c;. c c -.8:;::; u r <J.)!- "- -+J '+- UJ C C <J.) U C... Vl U :::l..cl <J.) E :::l w... U... Vl "C <J.) C I- c :::: c -+J I- 18 r I I I Z Distance frm Centerline, In..6 a. Lw Inlet Temperature Level Fig. 15 Variatin f Cmbustin Parameters acrss the Tunnel Width 49

63 AEDC. TDR Test Sectin Width - 3 in. Test Cnditins Cl Prbe Psitin Pta = 5 psia Cl X = 2.8 Y=... r C'C C]) l... ~ V') V') C]) l... CL r:,. ~r:,. L,Pt"Pt n tes\fuel r. 18 _[... I- ~r:,.~ O. 17 Test fuel n ~Y2 < w N~ >->{S.8 c: - c: C]).-.- u 6"Ri~ l l.j..i c: c: Q ~-~~.4 B.2 c:... V') t:; u ~ ~ a:;e u. U... " V') c: 28 ~r _ C'C B-'-J~ C])~ T ~ t 26 :::J r... l... C]) Cl... E C]) I-... r I :::J 2 L..-_--J.....J,."",,_...I. """"-..._...I Z Distance frm Centerli ne, In. b. Medium Inlet Temperature Level Fig. 15 Cntinued 5

64 AEDC TDR c:t:"' -.22 r c:t:"' c " I-.f ' ::J ~ ~ 28 E CI.) I- c ~ 26 / W N >.~ 1. ~ u c c O 8 :.;::;.~ u ~ t "E L..l.J CI.) C U 6 O 4 c :.;::; VI (.) ::J.c.2 ~ ~ (.) O +-'"C ~ C 1-. c Test Sectin Width - 3 in. Prbe Psitin X=3. Y=O Test Cnditins P t = 5 psia _...I.....I..._...-.J...L.....I..-_--I Z Distance frm Centerline, In. c. High Inlet Temperature Fig. 15 Cncluded 51

65 AEDC TDR Syml b. b. Cl Y2 Range > O. 7 Test Sectin Width - 3 in. Prbe Psitin X = 3. Y=O Z = ±O. 5 Test Cnditins Pt = 5 psia.8 UJ.7 >, u C Q).6 u ;;=: -lj..j c.5 :.= VI ~.4 E u.3.2 O. 1 u.~~~-w~ ~ ~~ ~ ~ ~~ ~ ~ ~~ Temperature, T t ' OR Fig. 16 Cmbustin Efficiency as a Functin f Inlet Temperature 52

66 MOO~i Test Sectin Width - 3 in. Prbe Psitin Y=O 41- z=o Test Cnditins Pta = 5 psia 36 Ttal Temperature, T t :::. CJ1 c..:i CD~ I.- ::::J +J C'O I.- CD Cl. E CD ~ Cmbustin Efficiency, E = l. j.8.6 ~ ~ Equivalence Rati K.5 l. l Axial (X) Distance frm Nrmal Shck, In. Fig. 17 Variatin f Flw Parameters n Centerline with lest Fuel Cmbustin..-:!::"' "'-l C'O \J)+ - +-' C'O w:::. c CD u._ C... CD V'l - ::::J C'O.> ~ "'-l (j'>. c- CD ~.- u - E' ::::J u 3 " c C'O > m. (). -I ;; ~ '" '-I >

67 AEDC TDR tv ( c: (]).8 u '+-LJ.J - c: V').6 :J..c E u.4 Nrmal Shck Psitin Test Sectin Width - 6 in. Prbe Psitin X=-.5 Y=O z=o Test Cnditins Pta = 45 psia ~ y 2 + a2 = 1. 5 at shck ttt = 272R at shck 1 Y2 + a2 = 1. 2 at shck T t = 236 R at shck " I Micrsecnd 2 Fig. 18 Variatin f Cmbustin Efficiency with Residue Time Aft f the Nrmal Shck 54

68 AEDC TDR 62 7& ~ I r--1 VI ~ 4 u Q) VI " u E x - " Q) ::: 2 VI Q) 2: =., ~ r--1 N ~ 1 : ~ 8 "C "C I 6 1r ~ Test Sectin Width - 6 in. Prbe Psitin X=-.5 Y = Z = Test Cnditins Pf = 45 psia \ Y2 + a2 = 1. 5 at shck ITt = 272R at shck, Y 2 + a2 = 1. 2 at shck ITt = 236 R at shck - -- d-r E = 1. 6 x 1 4 cal/gm mle ~ ~ E = 1.46 x 1 4 cal/gm mle " " ~ E = x 1 4 cal/gm mle 4 "' 3~----~----~------~----~~----~----~.26.3 O. 34 O. 38 O lit, R- 1 x 13 Fig. 19 Crrelatin f a Glbal Rate Equatin fr the Hydrgen-Oxygen Reactin 55

69 1. > m (). -l ;. - ~ '-I pi.99 BTest Sectin Width - 3 in..98 r Prbe Psitin.97 l- X = 3. Y=O.96 Z = ±O. 3 t pf Test Cnditins u~ -p-i.95 Pt = 45 psia CJ1 ) t P. 94 T t ' R O. 93 ~ 146R.92 ~ 17-18R.91 I cPR 19-2cPR.9 O O. 7 Equivalence Rati, Y Fig. 2 Ttal Pressure Lss vs Fuel Cncentratin with Near-Zer Heat Release

70 J O. 96 O. 94 pi O. 92 t pf O. 9 -p-i t P Test Sectin Width - 3 in. Prbe Psitin X = 3. Y=O Z = ±.3 Test Cnditins Pt = 45 psia 8% 4% % Cmbustin Efficiency (E) Symbl Cmbustin Efficiency -5 t, O O. 7 Equivalence Rati, 12 Fig.21 Ttal Pressure Lss vs Fuel Cncentratin at Varius Cnnbustin Efficiency Values.8 O. 9» m () I -I ;; I - ':'.l...

71 1. O. 98 Test Sectin Width - 3 in. Prbe Psitin X = 3. Symbl Y = Z = ±. 3 Test Cnditins Pta = 5 psia \l Equivalence Rati (Y2) >.5 > m ().. -I ; a- t;-' '-I (Xl _ 'D- 1_ D- +-' +-' D- D ' r :::: Cl.l c.n... ::J CX) Vl Vl Cl.l... - '"'CJ Cl.l +-' u Cl.l u O. 9 O Temperature Rati, TtlT t Fig.22 Crrected Ttal Pressure Lss vs Temperature Rati Three Inches Aft f the Nrmal Shck

72 CJl CO... c c ctj c:::: CI.) "- :::J VI VI CI.) "- a.. u ~ ctj... U').24 r' Test Sectin Width - 6 in. Prbe Psitin. 2 ~ Calculated at centerline n_"..16 I- " ".12 ~.8 I-.4 I-,," Calculated at centerline " " ",~ "~ '-8_... ~... g... 8 X = -.5 Y=O Z=O Test Cnditins P = 45 psia t ) Y2 =.22 at shck l T = 29 R at shck t 1 Test Fuel Off T = 296 R at shck t Q ~!----~------~----~------~----~----~------~----~----~.4 O Axial Psitin, I n. Aft f Shck Wave Fig.23 Variatin f Flw Parameters with Axial Distance Aft f Nrmal Shck Wave with Test Fuel» m -l. ; - r:" -..j

73 AEDC.TDR ::: 4 I-~ Q.)- 38 "- :::l +-' re "- 36 Q.) Cl.. E Q.) l- re +-' I Cl.. I _ Cl.. 1. ~ ~ - :;:; re.98 Test Sectin Width - 6 in. Ttal Temperature, T t Prbe Psitin ~ 1.1 Y=O z= / 1..9 ~ Cnditins Pta = 45 psla.8 TestFuel - Y2 + a2 = 1. 5 at shck T ta = 272R at shck O. 7.6 ~ed Fuel, (y )(l-e) + a ~.4 :::.96 Q Experi mental Pressure Lss Q.) "- :::l Vl.94 Vl Q.) '-... ".92 Q.) +-' U Q.) "- "-.9 u.88 O Q Q.3 N re + W I.--i ~N >- - Q.) :::l L.J... " c.,..- "- :::l. c ;::) X Distance Aft Nrmal Shck, In, a. Tt at shck 27SR Fig. 24 Cmparisn f Calculated Pressure Lss with Experimental Pressure Lss fr Heat Additin Aft f the Nrmal Shck 6

74 AE DC-TD R ::: I a.i 32 '- ::::l... 3 r '- Cl.l CL E Cl.l I- r... I Test Sectin Width - 6 in. Prbe Psitin Y=O Z = T est Cnditin s Pt = 45 psia Ttal Temperature, T t Test Fuel - Y2 + a2 =1. 2 at shck T t = 236cPR at shck (Y 2 )(! -E) + a O. 9.8 O. 7.6 N r + lij I... ~N. - Cl.l ::::l l.l ' Cl.l C '- ::::l..cl c :::::l I-ct"' CL... CL :.;:; r ::: CL Cl.l '- ::::l Vl.94 Vl Cl.l '- Cl... - Cl.l... U Cl.l '- '-.::> U Theretical Pressure Lss Experimental Pressure Lss X Distance Aft Nrmal ShOCK, In. b. T t at shck 235 R Fig. 24 Cncluded 61

75 ,r EMI.SSlON ZONE» m n -I ;: '"... ex> t-.) O":l t\:), PROBE OBLIQUE S WEDGE..., AND SUPPORT. Fig. 25 Test Sectin Schlieren and Emissin Phtgraph with Test Fuel On

76 AEDC TDR III G.I.....c ::: :r:.. c -a. Cl -:;..c fl.. c III III E W c '';: U G.I ti)... III G.I.... ~ LL 63

77 AEDC.TDR TT >3 R Fig. 27 Test Sectin Emissin Phtgraph with Oblique Shck Wave 64