Paper ID ICLASS Effects of Hole Geometry and Its Internal Flow on Spray and Mixture Properties of Hole-Type Injectors for a DISI Engine

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1 SNGLE SHOT A=T CLASS-26 Aug.27-Sep., 26, Kyoo, Japan Paper D CLASS6-66 Effecs of Hole Geomery and s nernal Flow on Spray and Mixure Properies of Hole-Type njecors for a DS Engine Kiyoaka SATO, Jun KANZAK 2, Masahisa YAMAKAWA, and Keiya NSHDA 3 Univerciy of Hiroshima, sao-kiyo@hiroshima-u.ac.jp 2 Suzuki Moor Corporaion, Kanzakij@hhq.suzuki.co.jp 3 Mazda Moor Corporaion, yamakawa.m@mazda.co.jp 4 Universiy of Hiroshima, nishida@mec.hiroshima-u.ac.jp ABSTRACT An experimenal and numerical sudy was conduced on he spray and mixure properies of he hole-ype injecors for D.. gasoline engines. The Laser Absorpion Scaering (LAS) echnique was adoped o simulaneously measure he spaial disribuions of he liquid and vapor phase concenraions in he fuel spray injeced ino a high-pressure and high-emperaure consan volume vessel. Effec of diameer and lengh-o-diameer raio of he nozzle hole L/D on he spray and mixure properies were examined. The smaller hole diameer and L/D produce he shorer ip peneraion, he wider vapor phase dispersion of he spray, and he larger mass of vapor phase fuel around he soichiomeric equivalence raio in he enire spray. The numerical analysis of a nozzle inernal flow was execued o his experimen resul. Keywords: Fuel Spray, nernal Combusion Engine, Gasoline Engine, Mixure Formaion, Laser Diagnosics. NTRODUCTON The combusion sysems used in he Direc njecion Spark gniion (DS) engines are based on he wall guided concep so far, which carries he combusible mixure o he spark plug locaion by he spray/wall ineracion []. n order o reduce he inheren smoke emission from he wall guided DS engines and o furher improve heir hermal efficiencies, aemps are being made o change he combusion sysem o he spray guided concep in order o avoid he wall weing of he fuel spray and he resulan rich mixure preparaion. n he spray guided combusion sysem, hole ype injecors are used due o heir consisen spray angle characerisics agains changing ambien pressure, which he swirl ype injecor used for he wall-guided combusion sysem does no have [2]. is a criical issue o clarify he mixure properies as well as he spray properies of he hole ype injecors in developing he spray guided combusion sysems for he DS engines. One of he auhors have developed he LAS (Laser Absorpion Scaering) echnique, which is he simulaneous and quaniaive measuring mehod of he liquid and vapor phase concenraion disribuions in he diesel-like fuel spray [3,4,5]. Recenly wo of he auhors have applied he LAS echnique o he analysis of he gasoline-like fuel spray [6,7]. n his sudy, he applicaion of he LAS echnique was made of he gasoline-like fuel spray injeced by he hole ype injecor for he DS engines. Effecs of he hole geomery, such as hole diameer and lengh-o-diameer raio of he nozzle hole (L/D raio), on he spray and mixure properies were clarified. The experimenal resuls were compared wih he calculaed resuls by Compuaional Fluid Dynamics (CFD). 2. High-Pressure and High-Temperaure Consan Volume Vessel and LAS Sysem Schemaics of he high-pressure and high-emperaure consan volume vessel, he fuel injecion sysem and he LAS sysem are shown in Fig. and experimenal condiions are shown in Table. The ambien gas is nirogen, is pressure and emperaure was se a.mpa and 5K, respecively. This condiion imiaed he compression sroke of he D gasoline engine. Four kinds of injecors where he diameer and L/D raio were differen were used. njecion pressure was se a 2MPa, and quaniy a 3.47mg. As shown in Fig. he spray was injeced ino he high-pressure and high-emperaure consan volume vessel. The spray was irradiaed by wo-wavelengh beams, one a ulraviole band 266 nm and he oher a visible band 532 nm. The ligh exincion images ha were aenuaed in he spray was separaed he ulraviole and he visible beam again and capured by wo CCD cameras. The images were ransferred o a compuer for he LAS image analysis. Delay Pulse Generaors Reflecion Nd:YAG Laser BP Filer & Aperure UV+Visible Beams P Fuel Accumulaor njecor Driver N 2 Cylinder njecor Dichroic Dichroic UV Beam Dichroic Diffuser Consan Volume Vessel Ulraviole mage Visible mage Reflecion Vis. Beam Beam Expanders Reflecion 2. EXPERMENTAL APPARATUS AND PROCEDURES CCD Cameras Compuers Fig. Experimenal Apparaus

2 Ambien Gas Temperaure:T a [K] Pressure:P a [MPa] Ambien Condiion Nirogen 5 njecion Condiion Fuel njecer Number of Holes P-xylene Hole Type Hole Diameer [mm] L/D njecion Duraion [ms] njecion Pressure [MPa] njecion Quaniy [mg] Principle of Laser Absorpion Scaering (LAS) Technique [6,7] As shown in Fig. 2, a wo-wavelengh (λ A : absorpion wavelengh, λ T : ransparen wavelengh) inciden ligh of inensiy Ι ransmis hrough a mixure of boh vapor phase and liquid phase droples, and is aenuaed ino a ransmied ligh of inensiy Ι. The exincion of absorpion wavelengh ligh log(ι /Ι ) λa is aribued o he liquid phase scaering and absorpion log(ι /Ι ) Lsca+Labs as well as he vapor phase absorpion log(ι /Ι ) Vabs, and is exincion rae is defined by Eq. (). The exincion of ransparen wavelengh ligh log(ι / Ι ) λτ is aribued o only he liquid phase scaering log(ι / Ι ) Lsca and is exincion rae is defined by Eq. (2). log log log + log = + () λa λt Table Experimenal Condiions nciden Ligh (λ A ) (λ T ) Lsca log = log (2) Lsca Because i is confirmed ha he liquid phase absorpion log( / ) Labs ha is he 2nd member a he righ side of Eq. () can be disregarded [5,6], and he liquid phase scaering log( / ) Lsca of boh wavelengh is almos idenical [5,6], he exincion raes by he vapor absorpion and he liquid scaering can be derived as Eqs. (3) and (4), respecively. Based on Eq. (3), exincion by he vapor phase log(ι /Ι ) Vabs is gained by subracing he exincion of ransparen wavelengh log(ι / Ι ) λτ from he exincion of absorpion wavelengh log(ι / Ι ) λa. log log log = (3) Vabs Labs λ A λ T Transmied Ligh (λ A ) (λ T ) Fig. 2 Exincion of nciden Ligh hrough Evaporaing Spray a Wavelenghs λ A and λ T Vabs log = log (4) Lsca λt n his sudy, he fourh harmonic oupu (wavelengh 266nm) of an Nd:YAG laser was adoped as he absorpion wavelengh λ A, and he second harmonic oupu (wavelengh 532 nm) as he ransparen wavelengh λ T, since he es fuel (p-xylene) srongly absorbs he ulraviole ligh (266 nm) and is ransparen a he visible ligh (532 nm) [6]. Based on Lamber-Beer s law and he onion-peeling model, he concenraion disribuions of he vapor phase fuel were obained. By summing up he vapor mass over he whole spray, he oal mass of vapor in he spray was obained. By subracing he oal mass of vapor from he mass of fuel injeced, he oal mass of droples in he spray was obained. By adoping he onion-peeling model and Bouguer-Lamber-Beer s law, he concenraion disribuions of he liquid phase fuel were obained. 3. RESULTS AND DSCUSSON 3. Equivalence Raio Disribuions of Liquid and Vapor Phases Figure 4 shows he equivalence raio disribuions of he liquid and vapor phases in he fuel spray. The lef hand side of each disribuion in Fig. 4 shows he liquid phase and he righ hand side shows he vapor phase. The images were aken a 2.ms afer he sar of injecion when he fuel injecion was finished for all cases. Since he injecion quaniy was adjused o 3.47mg for various hole diameer and L/D raio injecors, he injecion duraion is differen according o he injecor. The duraion from he end of injecion (EO) o he imaging iming for he small hole diameer D=.35mm is.42ms (Fig. 4(a), L/D=) and.89ms (Fig. 4(b), L/D=), and for he large hole diameer D=.55mm,.582ms (Fig. 4(c), L/D=) and.5ms (Fig. 4(d), L/D=). Thus, as is seen in Figs. 4(a) and (b), he region wih he relaively high liquid phase equivalence raio appears in he viciniy of he injecor for D=.35mm, while he liquid phase equivalence raio is no so high for D=.55mm in Figs. 4(c) and (d). The spray ip peneraion could be defined by he peneraion of he vapor phase whose equivalence raio is φ V =.. The spray ip peneraion of he injecors wih he small hole diameer D=.35mm is shorer han ha wih he large hole diameer D=.55mm regardless of he hole L/D raio. The spray ip peneraion of he nozzle wih small L/D raio is shorer han ha wih large L/D raio wihin he same hole diameer. The liquid phase peneraion could be defined as he farhes locaion of he liquid phase region, for example, wih an equivalence raio of φ L =.2. The change of he liquid phase peneraion for he hole diameer and L/D raio is similar o he spray ip peneraion, ha is, shorer liquid phase peneraion for small hole diameer D=.35mm and small L/D raio. As is found clearly in Figs. 4(c) and (d), ha are L/D= and for D=.55mm, he liquid phase wih φ L =.-.2 is disribued in he cenral region along he spray axis, disan from he spray ip and ail. On he conrary, he high vapor phase equivalence raio is disribued a he injecor-side region and he spray ip-side

3 region, which are a lile differen from he liquid phase disribuion. When he liquid fuel in he spray evaporaes, he vapor is dropped from he liquid phase flow ino he ambien gas and hen i is disribued behind he liquid phase. The vapor phase around he spray ip is caugh up by he succeeding vapor phase flow, hen he high vapor phase equivalence raio appears around he spray ip. (a) D=.35mm L/D= (b) D=.35mm vapor/liquid phase equivalence raios. As shown in Figs. 5(a) and 6(a), he region wih he relaively high vapor phase equivalence raio appears in he viciniy of he spray ip for D=.35mm regardless of he hole L/D raio. Moreover, he axial disribuion of he vapor phase equivalence raio for D=.35mm shows he fla shape along he spray axis. This endency ha is he effec of hole diameer is similar for he condiion a ms afer he sar of injecion, hough he resul is no shown in he paper. The evaporaion of he fuel a ms has ended almos because enough ime passes from he EO. Therefore, i seems ha he effec of he hole diameer on he mixure properies of 2.ms and ms doesn' depend on differing he injecion duraion according o he hole diameer. Figures 5(b) and 6(b) show he axial disribuion of he liquid phase equivalence raio. There is a region wih he high liquid phase equivalence raio in he viciniy of he injecor for D=.35mm regardless of he hole L/D raio, since he duraion from he EO is shorer for D=.35mm han D=.55mm. Effec of L/D. Figures 7 and 8 show he effec of he hole L/D raio on he axial disribuions of vapor/liquid phase equivalence raios. As shown in Figs. 7(a) and 8(a), he region wih he high vapor phase equivalence raio appears in he whole spray for L/D= regardless of he hole diameer. This endency is more remarkable for D=.55mm shown in Fig. 8(a). Figures 7(b) and 8(b) show he axial disribuion of he liquid phase equivalence raio. Vapor Phase Equivalence Raio φv D=.35mm.2 D=.55mm Disance from njecor Tip mm (a) Vapor Phase Equivalence Raio φ V (c) D=.55mm (d) D=.55mm L/D= Fig. 4 Effec of Hole Geomery on Liquid and Vapor Phase Equivalence Raio Disribuions (P a =.MPa,T a =5K,M f =3.47mg, ASO =2ms) 3.2 Axial Disribuions of Vapor Phase Equivalence Raio Effec of hole diameer. Figures 5 and 6 show he effec of he hole diameer on he axial disribuions of Liquid Phase Equivalence Raio φl Disance from njecor Tip mm D=.35mm D=.55mm (b) Liquid Phase Equivalence Raio φ L Fig. 5 Effec of Hole Diameer on Axial Disribuions of Vapor/Liquid Equivalence Raios for L/D=, =2.ms

4 Vapor Phase Equivalence Raio φv D=.35mm.2 D=.55mm Disance from njecor Tip mm Vapor Phase Equivalence Raio φv.6.4 L/D= Disance from njecor Tip mm Liquid Phase Equivalence Raio φl (a) Vapor Phase Equivalence Raio φ V.6.4 D=.35mm.2 D=.55mm Disance from njecor Tip mm Liquid Phase Equivalence Raio φl (a) Vapor Phase Equivalence Raio φ V L/D= Disance from njecor Tip mm (b) Liquid Phase Equivalence Raio φ L Fig. 6 Effec of Hole Diameer on Axial Disribuions of Vapor/Liquid Equivalence Raios for, =2.ms Vapor Phase Equivalence Raio φv Liquid Phase Equivalence Raio φl L/D= Disance from njecor Tip mm (a) Vapor Phase Equivalence Raio φ V Disance from njecor Tip mm L/D= (b) Liquid Phase Equivalence Raio φ L Fig. 7 Effec of L/D on Axial Disribuions of Vapor/Liquid Equivalence Raios for D=.35mm, =2.ms There is a region wih he high liquid phase equivalence raio in he whole spray for L/D= regardless of he hole diameer. n he case of L/D=, he liquid phase equivalence raio is low, hen he vapor phase equivalence raio is high in he whole spray. 3.3 Radial Disribuion of Vapor Phase Equivalence Raio Figure 9 shows he radial disribuions of he vapor phase equivalence raio a Z=35mm downsream from he injecor ip. The axial disance of Z=35mm is abou he spark plug locaion in he spray guided combusion sysem arrangemen. n he case of he hole diameer D=.35mm and L/D=, here is a high disribuion of he vapor phase equivalence raio in he range of 5 o mm from he spray axis. Vapor Phase Equivalence Raio φv (b) Liquid Phase Equivalence Raio φ L Fig. 8 Effec of L/D on Axial Disribuions of Vapor/Liquid Equivalence Raios for D=.55mm, =2.ms Radial Disance mm D=.35mm L/D= D=.35mm D=.55mm L/D= D=.55mm Fig. 9 Radial Disribuions of Vapor Equivalence Raio a Z=35mm, =2.ms 5

5 3.4 Temporal Variaions of Vapor Phase Equivalence Raio a Spark Plug Locaion Figure shows emporal variaions of he vapor phase equivalence raio a he spark plug locaion, ha is, he axial disance of Z=35mm and he radial disance of R=5.mm from he spray axis. The arrow a he lef boom in Fig. indicaes he injecion duraion given o each injecor. When he injecor condiion is D=.35mm and L/D=, he high vapor phase equivalence raio is kep from.5ms o ms afer he sar of injecion. Vapor Phase Equivalence Raio φv njecion Duraion D=.35mm L/D=. D=.35mm. D=.55mm L/D=. D=.55mm..5 2 Time afer Sar of njecion ms Fig. Temporal Variaions of Vapor Equivalence Raio Disribuions a Radius R=5.mm for Axial Disance Z=35mm, =2.ms 3.5 Temporal Variaions of Mass of Vapor and Liquid Figures and 2 show emporal variaions of mass of vapor and liquid phases in he whole spray for L/D= and 2, respecively. Each figure includes wo emporal variaions for hole diameers of D=.35mm and D=.55mm. The mass of oal fuel increases as ime passes by he EO. The mass of a oal fuel reaches he injecion quaniy (3.47mg) a EO. The mass of fuel is divided ino he liquid phase, he rich vapor phase (.3<φ V ), vapor phase around he soichiomeric equivalence raio (.7<φ V <.3), and he lean vapor phase (φ V <.7)). Effec of hole diameer. As shown in Figs. (a) and (b), he mass of fuel of he lean mixure (φ V <.7) for D=.35mm is less han ha for D=.55mm from 2.ms o ms afer he sar of injecion. The mass of vapor phase fuel around he soichiomeric equivalence raio (.7<φ V <.3) for D=.35mm is more han ha for D=.55mm from 2.ms o ms afer he sar of injecion. Figures 2(a) and (b) show ha hese endencies are similar for he condiion of. Effec of L/D. As shown in Figs. (a) and 2(a), he mass of fuel of he lean mixure (φ V <.7) for L/D= is less han ha for from 2.ms o ms afer he sar of injecion. The mass of vapor phase fuel around he soichiomeric equivalence raio (.7<φ V <.3) for L/D= is more han ha for from 2.ms o ms afer he sar of injecion. Figures (b) and 2(b) show ha hese endencies are similar for he condiion of D=.55mm. 3.6 Mass Frequency of Vapor Phase Equivalence Raio Effec of hole diameer. Figure 3 shows he effec of he hole diameer on he mass frequency of he vapor phase equivalence raio over he enire spray a 2.ms afer he sar of injecion. Mass of Fuel mg Mass of Fuel mg Mass of Fuel mg Mass of Fuel mg <φv EO Liquid.7<φv<.3 φv< Time afer Sar of njecion ms EO (a) D=.35mm.3<φv Liquid.7<φv<.3 φv< Time afer Sar of njecion ms (b) D=.55mm Fig. Temporal Variaions of Mass of Vapor and Liquid in Spray for L/D=.3<φv EO Liquid.7<φv<.3 φv< Time afer Sar of njecion ms EO (a) D=.35mm.3<φv Liquid.7<φv<.3 φv< Time afer Sar of njecion ms (b) D=.55mm Fig. 2 Temporal Variaions of Mass of Vapor and Liquid in Spray for

6 The mass of vapor phase fuel around he soichiomeric equivalence raio φ V =. for he hole diameer D=.35mm is more han ha for D=.55mm. This endency is similar for he condiion of, hough he resul is no shown in his paper. Therefore, he mass of vapor phase fuel around he soichiomeric equivalence raio φ V =. for D=.35mm is more han ha for D=.55mm regardless of L/D raio. This endency ha is he effec of hole diameer is similar for he condiion a ms afer he sar of injecion, hough he resul is no shown in he paper. Therefore, i seems ha he effec of he hole diameer on he mixure properies of 2.ms and ms doesn' depend on differing he injecion duraion. Effec of L/D. Figure 4 shows he effec of L/D raio on he mass frequency of he vapor phase equivalence raio over he enire spray a 2.ms afer he sar of injecion. The mass of fuel vapor phase around he soichiomeric equivalence raio φ V =. for L/D= is more han ha for. This endency is similar for he condiion of D=.55mm, hough he resul is no shown in he paper. Therefore, he mass of vapor phase around he soichiomeric equivalence raio φ V =. for L/D= is more han ha for regardless of he hole diameer. Mass Frequency of Fuel Vapor Mfv φ/mfv D=.35mm D=.55mm Equivalence Raio of Fuel Vapor φ v Fig. 3 Effec of Hole Diameer on Mass Frequency of Vapor Phase Equivance Raio for L/D=, =2.ms locaion, and increase he mass of vapor phase fuel around he soichiomeric equivalence raio. n his secion, discussion is made on he correlaion of he inernal flow of he nozzle hole in he CFD calculaions wih hese spray and mixure characerisics[8]. The behavior of he inernal flow is considered as follows [9]. D=.35mm Pressure Boundary (nle) Secion C Pressure Boundary (Oule) Fig. 5 Compuaional model for CFD Secion A Secion B D=.55mm Secion A Secion B Mass Frequency of Fuel Vapor Mfv φ/mfv L/D= Equivalence Raio of Fuel Vapor φv L (a) Effec of Hole Diameer D D Secion A Secion B L Fig. 4 Effec of L/D on Mass Frequency of Vapor Phase Equivance Raio for D=.35mm, =2.ms 3.7 nernal Flow of Nozzle Hole As were described in he previous secions, he smaller hole diameer and he smaller L/D raio decrease he spray ip peneraion and liquid phase peneraion, increase he vapor phase equivalence raio a he spark plug L/D= (b) Effec of L/D Fig. 6 Compued Velociy Vecor Disribuions a he Secion C

7 Calculaions were carried ou wih STAR-CD, a commercial CFD applicaion. The compuaional hree-dimensional model employed in he simulaion of nozzle inernal flow is shown in Fig. 5. The oal number of cells used for his model was abou 6, and he minimum cell size is.7e-3 mm. As he numerical approach, he fuel and air flow of nozzle inernal was firs analyzed by using a wo-phase flow analysis mehod employing a volume of fluid (VOF) model and he sandard high Reynolds number k-epsilon urbulence model[][]. The VOF mehod was used o calculae he wo-phase gas-liquid flow, consising of fuel and air[2]. Ocane was used as fuel. The inle and he oule of he model were applied a pressure boundary condiion as shown in Fig. 5. Corresponding o he experimens, he pressure of 2MPa was given as he inle boundary condiion and he pressure of MPa was given as he oule boundary condiion. As he iniial condiions,he pressure MPa of he fluid regions are specified. Figures 6(a) and (b) show he velociy vecors in he nozzle region of cross secion C. Figures 7 and 8 show he spray axial velociy disribuions, radial velociy disribuions and urbulence kineic energy disribuions from near nozzle wall o cener of nozzle of cross secion B. Effec of hole diameer. Figure 7(a) shows he spray axial velociy disribuions when L/D=, and he nozzle hole diameer is differen. For boh of he hole diameers D=.35mm and D=.55mm, he similar disribuions were observed. This endency is similar a secion A. Figure 7(b) shows he radial velociy disribuions when L/D=, and he nozzle hole diameer is differen. The radial velociy for D=.55mm is faser han ha for D=.35mm a cener of nozzle and i is more same a near nozzle wall. Axial Velociy m/s Radial Velociy m/s (a) D=.35 L/D= D=.55 L/D= Disance from Nozzle Wall mm (b) D=.35 L/D= D=.55 L/D= Axial Velociy m/s Radial Velociy m/s (a) D=.35 L/D= D= Disance from Nozzle Wall mm (b) D=.35 L/D= D=.35 Turbulence Kineic Energy m 2 /s Disance from Nozzle Wall mm (c) D=.35 L/D= D=.55 L/D= Disance from Nozzle Wall mm Fig. 7 Effec of Hole Diameer on Spaial Variaion of (a) Axial Velociy (b) Radial Velociy (c) Turbulence Kineic Energy, from Nozzle Wall o Cener of Nozzle of Cross Secion B Turbulence Kineic Energy m 2 /s Disance from Nozzle Wall mm (c) D=.35 L/D= D= Disance from Nozzle Wall mm Fig. 8 Effec of L/D on Spaial Variaion of (a) Axial Velociy (b) Radial Velociy (c) Turbulence Kineic Energy, from Nozzle Wall o Cener of Nozzle of Cross Secion B

8 The radial velociy is an order ha is considerably less han he axial velociy. Figure 7(c) shows he urbulen kineic energy disribuions when L/D=, and he nozzle hole diameer is differen. The urbulen kineic energy for D=.35mm more han ha for D=.55mm from near nozzle wall o cener of nozzle. n he case of D=.55mm, he urbulence is aenuaed near he exi of he nozzle hole. Therefore he nozzle hole diameer of D=.35mm resuls in wider dispersion, larger spray angle, shorer peneraion, and enhances he fuel aomizaion and evaporaion. Effec of L/D. Figure 8(a) shows he spray axial velociy disribuions when he nozzle hole diameer D=.35mm, and L/D is differen. Figure 8(b) shows he radial velociy disribuions when he nozzle hole diameer D=.35mm, and L/D is differen. The radial velociy for L/D= is faser han ha for a cener of nozzle. Figure 8(b) shows he radial velociy disribuions when he nozzle hole diameer D=.35mm, and L/D is differen The radial velociy disribuions for D=.35mm is more han ha for D=.55mm from near nozzle wall o cener of nozzle. Figure 8(c) shows he urbulen kineic energy disribuions when he nozzle hole diameer D=.35mm, and L/D is differen. The urbulen kineic energy disribuions for D=.35mm is more han ha for D=.55mm from near nozzle wall o cener of nozzle. Therefore he nozzle hole of resuls in narrower dispersion, smaller spray angle, larger peneraion, and poor fuel aomizaion and evaporaion. The above discussion is corresponding o he experimen resuls shown in Figs 4, 9 and. However, more analyses of he inernal flow of he nozzle hole and is effec on he spray behaviors are required. 4. CONCLUSONS By using he laser absorpion and scaering (LAS) echnique, he mixure formaion processes in he DS engine sprays were invesigaed under differen nozzle hole diameers and L/D raios. The following conclusions were obained: () The spray ip peneraion of he nozzles wih he small hole diameer is shorer han ha wih he large hole diameer regardless of he hole L/D raio. The spray ip peneraion of he nozzles wih he small L/D raio is shorer han ha wih he large L/D raio regardless of he hole diameer. The change of he liquid phase peneraion for he hole diameer and L/D raio is similar o he spray ip peneraion, ha is, shorer liquid phase peneraion for small hole diameer and small L/D raio. (2) The axial disribuion of he vapor phase equivalence raio for he small hole diameer is flaer han ha for he large hole diameer regardless of he hole L/D raio. The axial disribuion of he vapor phase equivalence raio for he small L/D raio is higher han ha for he large L/D raio regardless of he hole diameer. (3) n he case of he small hole diameer and he small L/D raio, here is a high disribuion of he vapor phase equivalence raio in he spray boundary around he axial disance of he spark plug locaion. (4) The mass of fuel of he lean mixure (φ V <.7) for he small hole diameer is less han ha for he large hole diameer regardless of he hole L/D raio. The mass of fuel of he lean mixure for he small L/D raio is less han ha for he large L/D raio regardless of he hole diameer. The mass of vapor phase fuel around he soichiomeric equivalence raio (.7<φ V <.3) for he small hole diameer is more han ha for he large hole diameer. The mass of vapor phase fuel around he soichiomeric equivalence raio for he small L/D raio is more han ha for he large L/D raio regardless of he hole diameer. 5. REFERENCES. Ormann, R., Arnd, S., Raimann, J., Grzeszik, R. and Würfel, G., Mehods and Analysis of Fuel njecion, Mixure Preparaion and Charge Sraificaion in Differen Direc njeced S Engines, SAE Paper 2--97, pp. -7, Koike, M., Curren Sae and The Fuure of Gasoline D Engine, Engine Technology, Vol. 4, No. 4, pp. 4-2, 22. (in Japanese) 3. Suzuki, M., Nishida, K. and Hiroyasu, H., Simulaneous Concenraion Measuremen of Vapor and Liquid in an Evaporaing Diesel Spray, SAE Paper, No93863, pp. -23, Zhang, Y., Yoshizaki, T. and Nishida, K., maging of Droples and Vapor Disribuions in a Diesel Fuel Spray by Means of a Laser Absorpion-Scaering Technique, Applied Opics, Vol.39, No.33, pp , Zhang, Y., Yoshizaki, T. and Nishida, K., Quaniaive Measuremen of Drople and Vapor Concenraion Disribuions in Diesel Spray by Processing UV and Visible mages, SAE Paper, ,pp. -4, Yamakawa, M., Takaki, D., Li, T., Zhang, Y. and Nishida, K., Quaniaive Measuremen of Liquid and Vapor Phase Concenraion Disribuions in a D.. 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