Study of Natural Gas Engine using Non-Premixed Combustion Model

Abstract

Direct injection natural gas engines are used in many heavy duty vehicles. Similar to diesel engines, high thermal efficiency and power density is maintained in such direct injection natural gas engines. In such engines, natural gas is injected directly into the combustion chamber. Then the gas mixes with the high pressure air in the combustion chamber and combustion occurs. The main objective is to simulate a cycle, from the end of the compression stroke to 50° after TDC. Simulation would be done keeping methane as fuel. A 30 degree sector of a 4-stroke engine which corresponds to one fuel injector hole is modeled. Since combustion simulation is to be studied, the simulation starts at 20 degree crank angle (CA) before the start of injection (SOI) and ends at 50 degree CA after top dead center (TDC). A simplified model of the engine with no valves is modeled since during the entire combustion process, both the valves remain closed.