A Two-Dimensional Computer Simulation of a Low Pressure Direct Injection Stratified Charge Rotary Engine : Cycle-to-Cycle Variation of Air-Fuel Mixture Distribution

Abstract

This numerical study focuses on optimization of the rotor geometry and influences of flow variation on the fuel distribution inside an LDISC (Low Pressure Direct Injection Stratified Charge)rotary engine system consisting of all three combustion chambers and both intake and exhaust port. A Chakraverthy third-order scheme devised in the numerical code has successfully solved the Compressible Navier-Stokes equations with binary diffusion between air and propane. Keeping the engine speed at 3000 rpm and without throttling, five cycles for one rotor geometry and one for another are calculated. The results show that one rotor geometry is quite favorable for stratification while the other is not, hence the choice of rotor shape is found to play a significant role in forming stratification. Although it is also observed that cycle-to-cycle variation of the flow fields often works against stratification, the paper concludes that an application of the LDISC to a rotary engine may extends it lean-limit dramatically.