An air-blast atomizer consisting of a plain orifice nozzle and dual counter-rotating radial swirlers was experimentally investigated to obtain sauter mean diameter(SMD) and Rosin-Rammler distribution parameter at different pressure drops and air-fuel ratios.The mean diameter and distribution parameter of fuel spray were measured by Marlven particle size analyzer.The experimental results show that the SMD and distribution parameter of fuel spray decrease with increasing air pressure drop and air-fuel ratio

and a critical air-fuel ratio occurs in the transitional process

when the actual air-fuel ratio exceeds the critical

the SMD and the distribution parameter change little with changing air pressure drop and air-fuel ratio