Effect of Gas injector direction on mixture formation in a spark ignition engine

Compressed natural gas as a hydrocarbon fuel that its combustion has the lowest exhaust emissions, is very applicable in internal combustion engines. In this way, gas injector role in fuel dispersion in intake manifold and entrance to in-cylinder space during intake-stroke and mixture formation, is very important. In this paper was tried to investigate effect of direction of injected fuel on in-cylinder mixture formation. First, and spark ignition engine was simulated with computational fluid dynamics in a full cycle and validation of results of in-cylinder pressure during cycle and mass of fuel and air at intake valve close time carried out. Finally, , gas-injectordirection, on fuel and air-trapped in combustion chamber, lambda ratio, turbulent kinetic energy and equivalence ratio distribution in cylinder space were investigated. The results show that gas-injector oriantation has not considerable effect on in-cylinder mixture formation in spark time but causes to reduction in-cylinder average swirl number.