自動車用インジェクタの燃料噴霧・混合気一貫解析

抄録

The fuel spray contains multi-scale free surfaces; liquid films formed at the fuel-injector outlet, ligaments generated by the liquid-film breakup, and droplets generated from the ligaments within air/fuel mixture region. In order to simulate the multi-scale free surfaces, we previously developed a fuel spray simulation combining the liquid-film breakup near the injector outlet with the air/fuel mixture. In the air/fuel mixture simulation, droplet-motions were calculated by using Discrete Droplet Model (DDM). Distributions of droplet diameters and velocities, calculated in liquid-film breakup simulation, were used as an injection condition of DDM. We apply our method to simulate fuel sprays from two kinds of fuel injectors: a multi-hole fuel injector and a collision fuel injector. The simulation results are compared with the measurements. The spray distributions qualitatively agree well with measurements. We also study the effects of injection condition of DDM on the fuel spray from collision fuel injector; some sets of velocity and diameter distributions of droplets are simulated. It is found that the diameter distribution of droplets near the injector outlet mainly affects the leading edge of spray.