The effect of combustion chamber geometry on injection and mixture preparation in a CNG direct injection SI engine

摘要: Abstract In pursuing a project to convert four cylinder gasoline multi-point port fuel injection engine CNG direct engine, numerical model has been developed in AVL FIRE software undertake detailed investigation on the effects of combustion chamber geometry such engines. Two main phases have considered present study. first phase, aiming fully investigate flow field and mixing process, multi-dimensional modeling transient gas performed. order verify accuracy model, two different validation cases employed. The results showed that models are quite capable grasping all significant physical phenomena process. Adoption was found be challenging task because required computational effort instabilities. cases, experimental were observed excellent agreement with each other. second using moving mesh capability validated include methane into for various geometries. Five piston head shapes along injector types single hole multi taken consideration. A centrally mounted location adapted cases. geometry, parameters, type shape studied air–fuel inside cylinder. Based results, suitable geometrical configuration new NG DI discussed.