Effects of Injection Pressure and Nozzle Diameter on Flame Structure of Diesel Spray of Agriculture Machine

摘要

Due to the mixing process of fuel and air in diesel engine, various diesel spray devices have been developed. More than one hundred years of development have made these diesel engines controllable and efficient, resulting in cleaner performance and enhanced fuel consumption. Still series of features: engine geometries, fuels, chemical-kinetics, in-cylinder flow, combustion process, sprays and fuel-air mixture formation must be investigating to reduce engine emissions, and increase performance of the engine. Alteration in fuel droplet and fuel-air mixture is one of the advanced elucidations in diesel engine. The injection pressure, ambient temperature and nozzle diameter can alter the fuel droplet and flame during combustion. The effects of injection pressure and nozzle hole diameter on flame structure and of impinging diesel spray were investigated. CFD software ANSYS IC Engine (Fluent) V-18 was employed to investigate such effects. For the injector nozzle having 0.18 mm diameter, injection pressure (140 MPa) with ambiet temperature 500 °K generates appreciably larger flame structure. Impinging spray flame of nozzle hole 0.1 mm shows much smaller size. The movement of the high velocity region was demonstrated to be at the injector tip in the beginning of injection period (340° CA) which accompanied with the high pressure region. That satisfy the fact which is as spray cone be larger, the spray generates more and more swirl dominant flow that lead to higher evaporation rate. Furthermore, the maximum velocity of injection under 70 MPa was decreased by 15.1093% than its value under 140 MPa. That satisfies the physical concept of pressure to velocity relation for compressible flow. Also, the maximum velocity of flow field with 0.1mm, injector diameter, was decreased by 26.5425% than its value in the case of 0.18 mm diameter.