Optimization of Injector Location on the Cylinder Head in a Direct Injection Spark Ignition Engine

Abstract

The injector location and orientation on the cylinder head of a direct injection spark ignition engine greatly influence the performance, combustion, and emission characteristics. As the cylinder head is the most crowded area, an in-cylinder investigation needs to be performed for the optimization of the spark plug and injector location. In this study, a gasoline direct injection (GDI) injector location was optimized for the upgradation of a port fuel injection (PFI) engine to direct injection engine. A computational fluid dynamics (CFD) tool of ANSYS Forte was used for the numerical simulation. The injector location was optimized based on the air-fuel homogeneity inside the combustion chamber at the time of ignition. A computational model was developed for the existing single-cylinder PFI research engine, and full-cycle simulation was performed for both motoring and combustion mode. An experimental analysis was performed and compared with the simulation results. It was found that the experimental in-cylinder pressure trace showed a good agreement with the simulation results. Prior to the numerical modeling, the GDI injector spray characterization was performed numerically and validated with the existing literature. The possible GDI injector locations were identified by diagnosing the cylinder head. The spray data was used at different possible locations and injected directly into the combustion chamber. The in-cylinder equivalence ratio at the time of ignition was presented for different injector locations and optimized based on the air-fuel homogeneity.