Abstract
Demand for performance improvement and reduction in emissions to meet stringent regulation standards lead to technological developments in automotive engines. The current port fuel injection in gasoline engine is considered for further developments with the help of direct injection. Spray guided GDI is one such technology, which holds the potential for better performance improvement paving the way for more adaption in production vehicle. Hence, a study to understand the effect of multiple injections in spray guided GDI engine is chosen. The primary objective of this study is to improve the performance of the spray guided GDI engine using multiple injection strategies. A wall guided GDI engine from the open literature with limited information on piston bowl geometry is chosen. 1-D simulation was carried out on the chosen engine in Ricardo WAVE to verify overall performance characteristics. This wall guided GDI engine is modified for spray guided GDI engine with changes in spark plug and injector location. 3-D simulation was carried out in Ricardo VECTIS with various injection strategies and the results are analyzed. In-cylinder pressure and heat release rate produced in the combustion simulation are chosen for performance evaluation. Simulations are carried out with single injection on spray guided GDI engine by varying the start of injection (SOI). After analyzing the results and observing trend in incylinder pressure rise, double and triple injection simulations are carried out. A triple injection strategy has shown 35 % and 12 % higher peak in-cylinder pressure as compared to the single and double injection respectively. Also, the peak heat release rate increased by 32 % and 15 % as compared to the single and double injection respectively.