关键词: 燃料喷嘴;喷雾;气体雾化;液滴;压力效应;反压力

Abstract: An experimental study on atomization of an air-blast nozzle at high ambient pressures was carried out at High Pressure Lab. of Thermal Science and Propulsion Center, Purdue University, U. S. A. The mean drop diameters and the drop size distributions of the sprays for three liquids with viscosities of 0. 001,0. 050 and 0. 10 Pa·s at ambient pressure of 0. 1￣1. 8MPa were measured with Malvern Particle Size Analysiser.The experimental results show that for all liquids and all ambient pressures,the mean drop size always diminishes with increase in air/liquid ratio, This effect is enhanced for liquids of higher viscosity. It is also found in this study that the drop size distribution parameter increases with increase in ambient pressure,thus indicating a more uniform drop size in the spray.This study proves whether the mean drop size goes up or down with increase in air pressure depends on the liquid viscosity. For liquids of low viscosity, such as water, an increase in pressure causes the mean drop size to decrease. For liquids of high viscosity, the mean drop size is increased by an increase in air pressure.The experimental data obtained in the present investigation demonstrate that the semi-empirical equation for mean drop size is improved by using liquid density inthe expression for Reynolds number instead of air density.

Key words: Fuel injector;Spraying;Gas atomization;Drop;Pressure effect;Back pressure