CFD based optimization of the mixture formation in spark ignition direct injection CNG engine

This paper describes optimization of the combustion chamber geometry andinjection timing of a new generation of ef7 engine, where cng is directly injected to thecombustion chamber, with the aim of providing the best mixture at low and high speeds.the multi-objective genetic algorithm (moga) is coupled with the kiva computationalfluid dynamics (cfd) code, with grid generation, in order to maximize the ammablemass of the mixture. this would result in better combustion and improved fuel economy.the optimization variables related to the combustion chamber are seven geometry variablesand injection timing. through the present optimization, a great improvement in mixturedistribution is achieved. the optimization results show that early injection with a shallowbowl shape can be advantageous at high speeds, while late injection would result in betterresults at low speeds