earticle

영어

There are two types of fuel supply method in CNG vehicles. One is premixed ignition and the other is gas-jet ignition. In premixed ignition, the fuel is introduced with intake air so that homogeneous air-fuel mixture may form. The ignitability of this method depends on the global equivalence ratio. In gas-jet ignition, CNG is introduced directly into the engine combustion chamber. The overall mixture is stratified by retarded fuel injection. In this study, a visualization technique was employed to obtain fundamental properties regarding overall mixture formation and combustion characteristics of direct injected CNG fuel inside a constant volume chamber and engine. For gas-jet visualization, Schlieren high speed imaging is used with the effects of ambient pressure and impingement wall on mixture formation being investigated.