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i? <br /> 2214 Y.Ando at aL I Energy 30(2005)22016•-2218 <br /> 0.8 LEEGUI- eaii <br /> (he e0� n+d11 am <br /> 0.4 40 <br /> 0.2 i <br /> 0 <br /> -0.2 1 <br /> _W -30 0 30 60 90 <br /> CW*AfgIefde9AT7 <br /> Fig.11.ConVarism of ClUnuk ive heel Me=lacdlin for ditfercmt Mads at 10096 WOT,ignition timing a 27.B=1.0 air <br /> Mcm 114tio,eagitte speed-2000 min-t. <br /> components of Gas 1 are 32%,those of Gas 2 arc 20%.FlIrthermore,compared with methane,rate of <br /> active species development of hydrogen's reaction is much faster. <br /> Generally,as the engine speed becomes higher,turbulent combustion speed also becomes higher.But <br /> in case of using the engine fueled with a low-BTU gas,ignition delay does not become longer in the time <br /> domain,so it becomes longer in the crank angle domain.Therefore Ignition timing needs to be set earlier <br /> as engine speed becomes higher.But in case of Gas 2,ignition advance is set as early as 5 V.Before Top <br /> Dead Center(BTDG) at 2000 min 1, and further increase in ignition advance cannot be set, because <br /> condition of low-temperature and low-pressure prevent stable ignition. Additionally, as turbulence <br /> increases at the higher engine speed, the shrink of flammable range makes combustion unstable as <br /> described above.Coslmequently these facts make operations difficult in higher engine speed.Moreover,it <br /> is thought that long ignition delay, slow combustion speed and narrow flammable range provoke the <br /> torque fluctuations. <br /> Qs1(h 4maenrichiorwllrt7gas) Chs2(methane rich low4=gas) natuealgas <br /> tA8 -1 0.790 —X-0.937 —)L-0706 <br /> —, � —X-1� -- lA" <br /> fl.6 2.113 <br /> B � <br /> I a <br /> 02 A <br /> A A <br /> 10 <br /> -a2 <br /> -100 50 0 $o 100 <br /> (bank Angle 1d%ATt>L') <br /> Fig. 12.CDmParim of cunntlative:heat mieum schedules for diPFem t Wass at 100 percent WOT,MBT timing.several air <br /> txcesa red%engine speed-2000 min-'.'2—air exoess ratio. <br /> i <br />