撞击式喷雾特性的拉格朗日数值模拟

Spray characteristics of free spray and impinging spray were investigated numerically. An open source code KIVA-3V was adopted to simulate the previous experiments. To account for the droplet collision within the spray, a recent proposed pressure dependent droplet collision model was employed to simulate the droplet collision frequency and Sauter mean diameter(SMD)for different spray layouts under different ambient pressures(1MPa and 6MPa). The results show that collision dynamic for either the free spray or the impinging spray is dominated by droplet coalescence under relatively lower ambient pressure(1MPa), and the higher collision frequency for impinging spray results in the larger droplet size. However, for higher ambient pressure condition(6MPa), droplet bouncing dominates collision dynamic therefore the impinging spray possesses smaller droplet size than the free spray does, which is more conductive to the subsequent atomization and combustion. With the increasing of ambient pressure, the increasing aerodynamic residence and droplet bouncing dominate the impinging spray characteristics. It is believed that the research results can be used to improve fuel supply system in the future direct injection internal combustion engines.