An experimental study on spray characteristics of a typical periodic air-assist direct injection atomizer was presented.Attention was focused on the effect of a series of parameters (such as duration of fuel injection

space time

duration of air injection and pressure of air) on spray characteristics.The fuel employed was RP-3

and the medium employed was compressed air.Laser particle analyzer was employed for spray measurement.Duration of fuel injection

space time and duration of air injection was changed from 2ms to 8ms

-2ms to 5ms

and 2ms to 8ms

respectively.The range of air pressure provided was 0.1～0.65MPa .The results show that the performance of atomization is improved as the ratio of air and fuel is increased.The increase of air density and space time is also benificial for atomization.Additionally

the distribution uniformity index value may be greater while the range of drop-size spreads more widely and the mean diameter is higher.For condition of high pressure

mean drop size is correlated using empirical equations.