Measurement of Unburned Gas Temperature in an SI Engine Using Fiber-Optic Laser Interferometry

Transcription

1 Measuremen of Unburned Gas Temperaure in an SI Engine Using Fiber-Opic Laser Inerferomery by N. Kawahara (1), E. Tomia, K. Takasu and K. Goo (2) (1) Okayama Universiy Deparmen of Mechanical Engineering, Tsushima-Naka 3, Okayama 7-853; Japan (2) Yamaha Moor Co, Ld. (1) ABSTRACT A heerodyne inerferomery sysem wih a fiber-opic sensor was developed o measure he emperaure hisory of unburned gas in a spark-igniion engine. A polarizaion-preserving fiber and meal mirror were used as he fiber-opic sensor o deliver he es beam o and from he measuremen region. This fiber-opic sensor can be assembled in an engine cylinder head wihou a lo of changes of an acual engine. Adjusmen sysem in he sensor was revised o face he disribued index lens wih meal mirror. When he flame firs reaches he es beam, he beam is refraced so much ha he inerference signal is emporarily weakened; he flame arrival ime can be deermined from his phenomenon. Before he flame arrived a he developed fiber-opic sensor, measured emperaure was almos same wih he emperaure hisory afer he spark, assuming ha he process ha changes he unburned gas is adiabaic. In siu unburned gas emperaure measuremens in a commercially produced SI engine can be carried ou using developed fiber-opic heerodyne inereferomery sysem. Alhough he heerodyne inerferomery wih he developed fiber-opic sensor provides he mean emperaure along he line of sigh, he feasibiliy of our sysem was sufficien o be applied o emperaure hisory measuremen of an unburned gas compressed by flame propagaion in an engine cylinder. Spark plug Fiber-opic sensor Fig. 2 Phoograph and schemaic diagram of developed fiber-opic sensor Fig. 6 Phoographs of he spark-igniion engine wih fiber-opic sensor 1

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3 1. INTRODUCTION Higher hermal efficiency and reducion of polluan are of paricular ineres in improving he environmenal accepance of inernal combusion engines (Heywood, J.B ). There have recenly been inensive effors a developing hermal efficiency of inernal combusion engines. Beer hermal efficiency can be achieved by making a compression raio of engine higher. However, knocking prevens hermal efficiency being aained for a spark-igniion engine (Heywood, J.B. 1988; Pilling, M.J ). When a homogeneous fuel-air mixure burns in a spark igniion engine, he pressure and emperaure of he unburned mixure rise wih flame propagaion. Much aenion has focused on he sponaneous igniion of a porion of he unburned end-gas mixure in connecion wih engine knocking. The sponaneous auoigniion phenomena of he end-gas ha causes engine knocking is governed by he emperaure and pressure hisory of he end-gas. Sponaneous auo-igniion is based on he low-emperaure chemical kineics under he cool flame condiions (Bäuerle, B., e al., 1994). Alhough i is very imporan o know he emperaure hisory of he unburned gas, i is no easy o deermine he ransien emperaure of gas in a commercially produced spark igniion engine. For he in-cylinder gas emperaure measuremen, newer echnique wih high accuracy and high emporal resoluion has been required. Since hermocouples ypically lack he emporal resoluion, in-cylinder gas emperaure measuremens have been dominaed by opical diagnosics (Zhao, H, and Ladommaos, N., 21; Eckbreh, A.C. 1996). Orh e al. presened wo-dimensional emperaure measuremen using a combinaion of 2D laser-induced fluorescence (LIF) of hydroxyl radicals and 2D Rayleigh scaering (Orh, A., e al ). They measured a significan dependence of he emperaure on he mixure composiion, and confirmed he validiy of he flamele assumpion from he analysis if IH radicals and emperaure profiles. Schulz e al. used a unable KrF excimer laser for LIF o obain he quaniaive imaging of he niric oxide concenraion disribuion and emperaure field in an SI engine by Rayleigh scaering (Schulz, C., e al ). Kaminski e al. applied wo-line aomic fluorescence (TLAF) o inernal combusion engine (Kaminski, C. F., e al ). Precision of 14% on emperaure disribuion was obained in high emperaure and pressure condiion. LIF mehod has he poenial o provide quaniaive wo-dimensional emperaure disribuion, bu ime-series analysis is limied by he laser repeiion rae. Sanders e al. applied he wavelengh-agile absorpion specroscopy o deermine he in-cylinder gas emperaure in an HCCI engine (Sanders, S.T., e al. 23.). Several researchers have used coheren ani- Sokes Raman specroscopy (CARS), which is paricularly well suied o engines, since i produces a srong signal, o deermine he unburned mixure emperaure in a single-poin (Luch, R.P., e al. 1987; Bradley, D., e al. 1994; Bood, J., e al. 1997; Nakada, T, e al. 199; Akihama, K., and Asai, T. 1993). Bradley e al. checked measuremen accuracy of CARS sysem using high-emperaure/ high-pressure cell and firing engine. The accuracy of CARS in an engine cylinder is up o ±25 K (Bradley, D., e al. 1994) and i is limied o single-sho measuremens. Addiionally hese echniques are no feasible for he applicaion in producion engines due o he need of opical window o access ino he cylinder. Moreover, here is inensive demand o know he ime-hisory of unburned gas emperaure in pracical engines especially. Laser inerferomery (Garforh, A.M. 1976) offers boh high poenial resoluion and non-inrusive emperaure measuremen. Several researchers have applied his echnique o emperaure measuremens (Achasov, O., e al. 1993; Hamamoo, Y., e al. 1994). In general, i is considered ha laser inerferomery has problems, which are sensiiviy o mechanical vibraions, and inapplicabiliy o an acual engine. However, Hamamoo e al. (1994) and Tomia e al. (1994, 2) insalled Mach-Zehnder inerferomery wih polarizaion preserving fibers and Köser prisms ino he spacer of cylinder. They measured he emperaure change of a compressed unburned gas during flame propagaion and invesigaed he knock phenomenon. However applicaion of his sysem was resriced due o he special-ype spacer. Therefore, a fiber-opic heerodyne inerferomery sysem has been developed o provide non-inrusive measuremens of he emperaure hisory for an unburned end-gas in an engine cylinder during flame propagaion wih a high emporal resoluion (Kawahara, N., e al. 21; Kawahara, N., e al. 22). Fiber opical heerodyne inerferomery is fairly insensiive o he flucuaions in signal inensiy caused by mechanical vibraion. Measuremen accuracy was discussed in consideraion of he accuracy of pressure measuremens, he sabiliy of he AOM sysem, he gas composiion, and he relaionship beween he bea and sampling frequencies. The uncerainy of his mehod is wihin ±1 K. Moreover, he feasibiliy of a emperaure sensor probe ha uses a polarized fiber and mirror was demonsraed. A fiber-opic sensor wih he polarized fiber and meal mirror, which is involved in heerodyne inerferomery sysem, were developed in order o insall ino a es engine (Kawahara, N., e al. 22). Measuremens of unburned gas in engine cylinder under he condiion of mooring and firing were performed. The feasibiliy and measuremen accuracy of his developed sensor for he use in a es engine was discussed. 3

4 In his sudy, he developed fiber-opic sensor wih he polarized fiber and meal mirror, which is involved in heerodyne inerferomery sysem, was revised in order o insall ino a spark-igniion engine. An opical sysem for an in-siu heerodyne inerferomery sysem for unburned gas emperaure measuremen in a spark-igniion engine was developed and esed under firing condiions wih propane as fuel. Measuremens of unburned gas in he cylinder of compressionexpansion engine under he firing condiions were performed. Moreover, he developed fiber-opic sensor was applied o a commercially produced spark igniion engine under he firing condiion. The feasibiliy of his developed sensor for he use in a producion spark igniion engine was discussed. 2. Mehod of unburned gas emperaure measuremen 2.1 Laser Heerodyne Inerferomery Sysem wih Fiber-Opic Sensor Figure 1 shows he configuraion of heerodyne inerferomery wih he fiber-opic sensor. A frequency sabilized He-Ne laser, wih a wavelengh λ s of nm and an oupu power of 1 mw, provides a linear polarized beam for he measuremens. The AOM sysem for heerodyne inerferomery produces wo beams. In his experimen, he frequency of he firs beam is shifed by 8.1MHz, and ha of he second by MHz. These beams mee a he polarized beam splier and creae a bea frequency of 25. khz. The difference beween he iniial frequencies can be alered o creae oher bea frequencies (12.5 ~ 1 khz), if desired. Afer he polarized beam splier, he beam is spli ino wo by he half mirror. One beam is deeced by a phoo-ransisor as a reference signal; he oher is used for modified Michelson inerferomery. The reference signal beam passes ouside he combusion chamber and is refleced by a mirror. The beam used for modified Michelson inerferomery passes hrough he es secion, is refleced by a mirror, and hen passes back hrough he es secion again. The delivery of he es beam poses a possible problem in heerodyne inerferomery since, any change in he posiion of he opical sysem in relaion o he combusion chamber affecs he resuls due o he sensiiviy of he signal. The polarizaion of he signal is imporan; herefore, a 1.5 m polarizaion-preserving fiber is used o deliver he es beam o and from he fiber-opic sensor, which is explained in he nex secion. The 1/2 wave rearder was used in he fiber-opic sysem, so ha he polarizaion angle of he fiber coincides wih he es beam. Manipulaor of LDV sysem was used o ener he beam ino he fiber. A disribued index lens is fixed a he oher end of he fiber o generae a collimaion beam and o inroduce he beam ino he fiber. This disribued index lens has an ani-reflecion coaing o decrease he cross-alk effec. The es beam passes hrough he fiber and mees he reference beam a he polarized beam splier, where he wo beams inerfere wih each oher. The frequency sabilized He-Ne laser used in hese ess has a long coherence lengh (over 1 km); hus, he difference beween he pah lenghs of he es and reference beams is insignifican. The inerfering ligh is guided o a phooransisor, and changes in he inensiy are deeced. Fiber-opic heerodyne inerferomery sysem wihou developed fiber-opic sensor were se on a vibraion isolaor. The reference signal, es signal and pressure daa are colleced using an A/D converer (maximum sampling rae: 5 khz). These daa are hen analyzed using in-house sofware. Opical fiber for preserving polarizaion He-Ne laser PBS HM M :Mirror HM :Half mirror AOM :Acousic opic AOM M PF modulaor PF :Polarizing filer PT PBS :Polarizing beam splier SML :Micro-lens Reference λ/4 : 1/4 wave rearder signal λ/2 : 1/2 wave rearder PT :Phoo-ransiser SML l /2 l /4 PBS PF PT Tes signal M Fiber-opic sensor Sampling gas 4

5 Fig. 1 Heerodyne inerferomery wih fiber-opic sensor 2.2 Principle of Temperaure Measuremen Inerferomeric mehods allow variaion in he refracive index along he line of sigh o be measured. When he unburned gas mixure is compressed by he pison or he flame developmen, he densiy of he gas in he combusion chamber changes affecing he refracive index. The refracive index is influenced simulaneously by boh emperaure and changes in species concenraions. The difference beween he opical pahs of he es and reference beams varies, and corresponds o changes in he refracive index in unburned mixure and he inerference ligh inensiy. The change of phase shif of he heerodyne signal over a given ime, ψ is expressed by ψ = πfb( ) d 2 2πf br ( ) d (1) where f br and f b denoe he bea frequency of he reference and es secions, respecively. The change of phase in he es secion, ψ, is also expressed by ψ = 2πΦ / λ = 2πn L / λ s s (2) where Φ is he change in he opical pah lengh, L is he lengh of he es secion, λ s is he wavelengh of he es beam, and n is he change in he refracive index in he es secion. The relaionship beween he refracive index and densiy can be approximaed using he Gladsone-Dale equaion, n ρ RG = 1 + = 1 + M P R R T G (3) where R G is he Gladsone-Dale consan (cm 3 /mol) (Gardiner, W.C.Jr,, e al. 198), which is deermined by he wavelengh of he laser and he gas species. The variables M, R, P, and T denoe he mean molecular weigh, mean gas consan, pressure, and emp eraure in he es secion, respecively. The value of he Gladsone-Dale consan for each gas is given in deail for each laser wavelengh in reference (Gardiner, W.C.Jr,, e al. 198). The emperaure of he mixure can be obained from Eqs. (1), (2), and (3), T = 2πP R T L G 2πP R L + ψ T R λ G (4) When he pressure P and emperaure T of he iniial sae are known, he emperaure of he gas can be calculaed from measuremens of he pressure and he change in bea frequency of he inerfering ligh. 2.3 Developed Fiber-Opic Sensor 5

6 Phoograph and schemaic diagram of developed fiber-opic sensor are shown in Fig. 2. Developed fiber-opic sensor is consised wih he polarized fiber and meal mirror. The fiber-opic sensor comes in conac wih high emperaure burned gas. Therefore sapphire glass as window and meal mirror as mirror secion were used in order o resis hea from burned gas. Adjusmen sysem in he sensor for maching he laser beam from and o he es region was revised. The developed sensor could be assemb led easily using he new adjusmen sysem. 7mm L/2 Meal mirror Measuremen region M5 Sapphire window SML Opical fiber Fig. 2 Phoograph and schemaic diagram of developed fiber-opic sensor Temperaure measuremen sysem using heerodyne inerferomery is he line of sigh measuremen mehod. Since longer lengh of measuremen region makes phase shif larger, signal o noise raio and measuremen accuracy will be beer using longer lengh of measuremen region. However, measured emperaure is averaged value inside he measuremen region so ha shor lengh should be beer. When he developed fiber-opic sensor is seled in a producion engine, lengh of sensor should be shorer due o he conac of inake and exhaus valve. The rade-off relaionship beween he lengh of measuremen region and measuremen resoluion should be opimized. The developed sensor has a doublepass measuremen lengh. In consideraion of he sensor lengh inside cylinder and he resoluion of emperaure measuremen, he lengh of measuremen region was deermined as 13. mm using double-pass measuremen lengh. I was very difficul o deermine he hermal boundary layer in he measuremen pah so ha he effec of hermal boundary layer on he measuremen lengh was no considered. 3. EXPERIMENTAL RESULTS 3.1 Temperaure Measuremen of Unburned End-Gas in a TEST engine A specially designed es engine ha could only be fired once was used for he experimens (Kawahara, N., e al. 21; Kawahara, N., e al. 22). The engine had a bore and sroke of 78 and 85 mm, respecively, and he compression raio was 8.9:1. The combusion chamber of his engine is pancake-ype. The engine was operaed a 6 rpm, and spark 6

7 iming was 2 degrees before TDC. The sensor was locaed a 64 mm lef from spark elecrode and lengh of he sensor inside cylinder was 8.8 mm. The cylinder and mixure ank were iniially charged wih a homogeneous mehane-air mixure (equivalence raio φ = 1., P = 1 kpa, T = 291 K). The emperaure of he fuel-air mixure a he sar of compression (base sae) had o be deermined in advance, because only he change in emperaure from he base sae was measured by he fiber-opic heerodyne inerferomery sysem. In his experimen, he valve was closed a BDC of a cerain cycle. Using a resisance wire as a hermomeer, he emperaure a BDC of he valve closure cycle was found o be 3.8 K lower han he iniial gas emperaure in he mixure ank (Tomia, e., e al. 1994). This value was used for he emperaure a he sar of compression. The compression-expansion engine provided opical access via an exended pison and a quarz window. Combusion inside he cylinder was visualized using a high-speed video camera (4,5 frames/sec) wih an image inensifier. By gaing he inensifier synchronously wih he engine, we were able o acquire an image a a specific crank angle. Unburned gas emperaure measuremen using heerodyne inerferomery sysem wih developed fiber-opic sensor and visualizaion of flame propagaion were obained simulaneously during one cycle. The unburned gas emperaure afer he valve closes can be obained from he daa concerning he pressure and he heerodyne signal. The emperaure hisory of he unburned end-gas from a crank angle of 21 ill he flame arrival ime a he sensor was calculaed using Eq. (4) and ploed wih solid line in Fig. 3. For comparison, anoher mehod for obaining he emperaure was presened wih broken lines. For he mixure, a polyropic change was assumed o be generaed by he spark iming whereas an adiabaic change was assumed afer he spark iming because he unburned gas was compressed due o here being almos no hea loss. As shown in Fig. 3, he emperaure under he assumpion of polyropic and adiabaic change was approximaely equal o he measured emperaure wih developed sysem. Figure 4 indicaes he flame propagaion phoographs a a specific crank angle. Circles in images indicaed he posiion of developed fiber-opic sensor. The obained crank angles were shown in Fig. 3. Spark elecrode was se in he righ hand side of he picures. The diameer of visualizaion area was 52 mm. The flame propagaed from righ o lef. The obained picures indicae ha he flame fron broadens wih he disance from he spark poin, because he flame fron is no planar. When he flame firs reaches he es beam, he beam is refraced so much ha he inerference signal is emporarily weakened; he flame arrival ime can be deermined from his phenomenon. Before he flame arrived a he developed sensor, measured emperaure was almos he same as he emperaure hisory afer he spark, assuming ha he process ha changes of he unburned gas is adiabaic as shown in Fig. 3. As described above, he sysem of his measuremen echnique was confirmed o be valuable for in-siu emperaure hisory measuremen in a simple es engine. Temperaure, K f=1., CH 4 -air mixure Heerodyne Polyropic and adiabaic Flame arrival Spark iming a b c d Crank angle, deg. (TDC) 7

8 Fig. 3 Temperaure change of unburned gas under firing condiion in he es engine Fiber-opic sensor Spark elecrode a (346 deg.) b (352 deg.) c (36 deg.) d (366 deg.) Fig. 4 Flame propagaion in he es engine 3.2 Temperaure Measuremen of Unburned Gas in a Prpducion Engine Nex, he developed fiber-opic sensor was applied o a commercially produced engine. A schemaic diagram of experimenal se-up is shown in Fig. 5. A four-sroke cycle spark-igniion engine wih single cylinder was used o es his measuremen echnique. The bore and sroke were 7 and 58 mm, respecively, and he compression raio was 9.5:1. Throle valve was almos closed a idling condiion. Propane was inroduced ino he inake pipe approximaely 1 m from he engine inake manifold. A saic mixer was placed in he inake pipe o produce a homogeneous mixure of propane-in air. The inle airflow rae was measured wih a laminar flow meer. The propane fuel flow rae was measured wih anoher laminar flow meer and adjused wih a needle valve. Figure 6 indicaes phoographs of a spark-igniion engine wih he developed fiber-opic sensor. The fiber-opic sensor was se in he cylinder head agains he spark plug. The measuremens of unburned gas emperaure compressed by he flame propagaion could be carried ou. The window of measuremen region was enough o ener unburned gas. Inake and exhaus valve did no conac wih housing of measuremen region. In-cylinder pressure was obained using a pressure ransducer se in he spark plug. Hisory of incylinder pressure was very imporan for he evaluaion of unburned gas emperaure. The engine was operaed a 1,5 rpm. Inake valve was closed a 251. The spark iming was 2 degree before TDC. In siu unburned gas emperaure measuremens were carried ou in he spark-igniion engine under firing condiions. Air cleaner Laminar flow meer Bore x sroke: 7 x 58 mm Compression raio : 9.5 Single cylinder Saic mixer Spark plug Laminar flow meer Surge ank Inake Exhaus Fiber opic sensor Propane Dynamomeer Spark plug Vibraion isolaor IN Ex He-Ne laser AOM PBS M l/2 HM PBS PF 8 SML l/4 PF PT PT M Thermocouple Fiber opic sensor

9 Fig. 5 Schemaic diagram of experimenal se-up using he spark-igniion engine Fiber-opic sensor (a) Spark-igniion engine wih fiber-opic sensor Spark plug Fiber-opic sensor (b) Engine cylinder head wih fiber-opic sensor Fig. 6 Phoographs of he spark-igniion engine wih fiber-opic sensor 9

10 Figure 7 indicaes he pressure hisory and he measured phase shif beween he reference and es signals under condiions peraining o an engine speed of 1,5 rpm. The phase shif is calculaed from he difference beween he reference and es signals using Eq. (1). TDC corresponds o a crank angle of 36. The phase shif increases slighly wih he pressure rise a he firs sage of compression; as he pressure increases afer he spark, he phase shif becomes larger. A he firs sage of compression (crank angle from 24 o 3 ), he phase shif flucuaed due o he mechanical vibraion of firing engine. During he firs sage of compression, pressure in he cylinder rises slighly. The effec of mechanical vibraion on he fiber canno be negleced. However, he phase shif became smooh line due o he large pressure rise from he crank angle of 3. Alhough he noise from mechanical vibraion conribued o he inerference signal during he flame propagaion, he effec was wihin he limis allowed for measuremen. The effec of he impac a he valve closure and he operaing vibraion of he engine were herefore sufficienly resrained o permi accurae heerodyne inerferomery measuremen. The emperaure hisory of he unburned gas from 3 o he flame arrival ime a he developed sensor was ploed wih solid line in Fig. 8. The unburned gas emperaure before he spark iming, calculaed using he polyropic index, and afer he spark iming, which is assumed by an adiabaic change, is shown wih a dashed line in Fig. 8. Iniial emperaure is very imporan for he measuremen mehod using laser inerferomery. The evaluaed emperaure using polyropic index a a crank angle of 3 was used for he iniial emperaure of laser inerferomery. Measured emperaure was lower han evaluaed mean emperaure using in-cylinder pressure. One of he reasons is ha he measuremen locaion was near he wall, where he emperaure is expeced o be lower han he mean emperaure. Unburned gas emperaure could be quanified using developed fiber-opic sensor in a spark-igniion engine. Alhough heerodyne inerferomery wih he developed fiber-opic sensor provides he mean emperaure along he line of sigh, his resul demonsraes ha his mehod can measure he emperaure hisory of unburned gas locally in an engine cylinder. I mus be emphasized ha he developed heerodyne inerferomery wih fiber-opic sensor has a good feasibiliy o measure he unburned gas emperaure hisory in he commercially produced spark-igniion engine. Phase shif, rad IVC Flame arrival Spark iming Pressure, MPa Crank angle, deg. (TDC) 39 Fig. 7 Measuremen phase shif and pressure under firing condiion in he spark-igniion engine Temperaure, K Heerodyne Polyropic and adiabaic 1 Spark iming Flame arrival

11 Fig. 8 Hisory of unburned gas emperaure obained in spark-igniion engine 4. CONCLUSIONS Temperaure measuremen sysem of unburned gas in a commercially produced engine was developed using laser heerodyne inerferomery wih a fiber-opic sensor. A polarizaion-preserving fiber and meal mirror were used as he fiber-opic sensor o deliver he es beam o and from he measuremen region. This fiber-opic sensor can be assembled in he engine cylinder or he cylinder head wihou a lo of changes of an acual engine. The feasibiliy of our sysem was sufficien o be applied o emperaure hisory measuremen of an unburned gas compressed by he flame propagaion in an engine cylinder. The measured value was almos he same as he averaged emperaure esimaed using he incylinder pressure. The developed heerodyne sysem may also be used for oher applicaions ha require a fas response ime o measure he densiy and pressure of a gas, and hereby obain a ransien emperaure record. REFERENCES Akihama, K., Asai, T. (1993). Improvemen in Temperaure Measuremen Accuracy of Q-Branch CARS Thermomery (Effecs of Specral Resoluion of Deecion Sysem), JSME Inernaional Journal, B 36-2, pp.364. Achasov, O., Fomin, N., Penyazkov, O., Oznobishin, A., and Fisson, F. (1993). Inerferomeric Sudy of Combusion in a Spark Iginiion Engine, Proc. of he In. Symp. on Inernal Comb. Engines, KONES'93, pp Bäuerle, B., Hoffmann, F., Behrend, F., and Warnaz, J. (1994). Deecion of Ho Spos in he End Gas of an Inernal Combusion Engine Using Two-dimensional LIF of Formaldehyde, Proc. Combus. Ins., 25, pp Bood, J., Bengsson, P-E., Mauss, F., Burgdorf, K., and Denbra, I. (1997). Knock in Spark-igniion Engines: End-gas Temperaure Measuremens using Roaional CARS and Deailed Kineic Calculaions of he Auoigniion Process, SAE paper Bradley, D., Kalghagi, G.T., Morley, C., Snowdon, P., and Yeo, J. (1994). CARS Temepraure Measuremens and he Cyclic Dispersion of Knock in Spark Igniion Engines, Proc. Combus. Ins. 25, pp Eckbreh, A.C. (1996). Laser Diagnosics for Combusion Temperaure and Species, 2nd Ed., Gordon and Breach Publishers. Gardiner, W.C.Jr, Hidaka, Y., and Tanzawa, T. (198). Refraciviy of Combusion Gases, Combus. and Flame, 4, pp Garforh, A.M. (1976). Unburn Gas Densiy Measuremens in a Spherical Combusion Bomb by Infinie-fringe Laser Inerferomery, Combus. and Flame, 26, pp

12 Hamamoo, Y., Tomia, E., and Jiang, D. (1994). Temperaure Measuremen of End Gas under Knocking Condiion in a Spark-Igniion Engine by Laser Inerferomery, JSAE Review, 15-2, pp Heywood, J.B. (1988). Inernal Combusion Engine Fundamenals, McGraw-Hill, Inc. Kaminski, C. F., Engsroem, J. and Alden, M. (1998). Spark igniion of Turbulen Mehane/Air Mixures Revealed by Time-Resolved Planar Laser-Induced Fluorescence and Direc Numerical Simulaions, Proc. Comb. Ins. 27, pp.85. Kawahara, N., Tomia, E., and Kamakura, H. (21). Transien Temperaure Measuremen of Gas Using Fiber Opic Heerodyne Inerferomery, SAE paper No Kawahara, N., Tomia, E., and Kamakura, H. (22), Unburned Gas Temperaure Measuremen in a Spark-igniion Engine Using Fiber-Opic Heerodyne Inerferomery, Meas. Sci. Technol., 13-1, pp Luch, R.P., Tees, R.E., Green, R.M., Palmer, R.E., and Ferguson, C.R. (1987). Unburned Gas Temperaure in an Inernal Combusion Engine. I: CARS Temperaure Measuremens, Comb us. Sci. and Technol., 55, pp.41. Nakada, T, Io, T., and Takagi, Y. (199). Unburn Gas Temperaure Measuremens Using Single Sho CARS in a Spark Igniion Engine, Proc. of In. Symp. on COMODIA 9, pp Orh, A., Sick, V., Wolfrum, J., Maly, R.R., Zahn, M. (1994). Simulaneous 2D Single-Sho Imaging of OH Concenraions and Temperaure Fields in an SI Engine Simulaor, Proc. Combus. Ins., 25, pp Pilling, M.J. (1997). Low-Temperaure Combusion and Auoigniion, Elsevier Science. Sanders, S.T., Kim, T., and Ghandhi, J.B. (23). Gas Temperaure Measuremens During Igniion in an HCCI Engine, SAE Paper No Schulz, C., Sick, V., Wolfrum, J., Drewes, V., Zahn, M., and Maly, R. (1996). Quaniaive 2D Single-Sho Imaging of NO Concenraions and Temperaures in a Transparen SI Engine, Proc. Comb. Ins. 26, pp Tomia, E., Hamamoo, Y., and Jiang, D. (1994). Temperaure and Pressure Hisories of End Gas under Knocking Condiion in a S.I. Engine, Proc. of In. Symp. on COMODIA 94, pp Tomia, E., Hamamoo, Y., and Jiang, D. (2). Measuremen of Temperaure Hisory of Unburned Gas Before Knocking in a Spark-Igniion Engine Using Laser Inerferomery, Meas. Sci. Technol., 11-6, pp Zhao, H, and Ladommaos, N. (21). Engine Combusion Insrumenaion and Diagnosics, Sociey of Auomoive Engineers, Inc. 12