Optimization of critical angle, distance and flow rate of secondary fuel injection in DI diesel engine using computational fluid dynamics

Abstract

This study presents the optimization of the intake manifold and the optimized flow rate of the acetylene gas which acts as a low reactivity fuel to achieve the superior performance and emission characteristics used in the Reactivity controlled compression ignition (RCCI) engine. Intake manifold is one of the engine components which are an important factor in determining the quality of combustion. A very recent evolution of the RCCI engine using the low temperature combustion technique requires a low reactivity fuel which is injected through the secondary fuel injector. The secondary fuel injector must be designed and optimized to allow the acetylene gas to maximize the engine performance and the amount of acetylene gas in liters per minute required for better combustion. If the secondary fuel injector is mounted apart from the critical point, then the performance of the RCCI engine may be poor and also if the acetylene gas is not supplied properly, there is a risk of poor combustion and also if the acetylene gas is supplied excessively, there is a risk of knocking along with the backfire due to the excess fuel charge accumulation during the combustion process. Physical testing of the secondary fuel injector in the intake manifold with different angles, distance and flow rate of supply of acetylene gas is time and cost consuming process. To mitigate this issue optimization is done through computational fluid dynamics principles comes in handy to minimize time and money. In our study, ANSYS-FLUENT software is used for simulation purposes. Optimization of acetylene gas injector distance is carried out by analyzing the pressure contours at the entrance of the combustion chamber. The optimized flow rate of acetylene gas and the injector inclination is found by analyzing the flow contours of turbulent kinetic energy and turbulent dissipation rate.