Simulation Study on the Impact of Uneven Fuel Injection of Each Hole of the Diesel Engine Injector on the Combustion Process

Abstract

The spray impulse and injection pressure of each hole of the 4-hole injector of F186 engine were tested by using the transient test system for flow coefficient and injection rate of each hole of the injector, and the injection rate, fuel injection quantity and flow coefficient of each hole were obtained. According to the measured injection rate of each hole and cycle fuel injection quantity, a 3D model of the diesel engine was established with the FIRE software, and the uniform injection rate and uneven injection rate of each hole were made as the injection setting for the combustion simulation to comparatively analyze the influence of the uneven injection rate of each hole on the combustion process of diesel engine. As the injection of each hole is uneven, some holes with high injection rate have long fuel spray penetration distance and the fuel spray is fully mixed with the air, and the ignition starting point is moved ahead. When compared with the case of uniform injection rate, the phase corresponding to the heat release rate in the case of uneven injection rate is moved forwards, the maximum cylinder pressure and temperature rise fast, the maximum cylinder pressure and maximum average temperature in cylinder are higher, the NO generation is larger, and the Soot generation is slightly larger. In the case of uneven injection rate from four holes, as the utilization of air in the hole-located cylinder space by the fuel spray is uneven, the hole with a large quantity of injection makes the oxygen in the hole-located cylinder space relatively low, the wall collision of the hole with high injection rate is more, and the diffusion combustion is incomplete and insufficient.