Abstract: In order to understand the impact of air supply pressure on the atomization characteristics and dust removal performance of fluid ultrasonic atomizing nozzle,the flow rate,atomization characteristics and dust removal performance of fluid ultrasonic atomizing nozzle are measured by means of the self developed atomization and dust removal experimental platform for underground coal mine.The atomization characteristic parameters of the nozzle involved in the experiment include atomization angle,range,droplet size,etc.The dust removal performance is evaluated according to full dust removal efficiency and respirable dust removal efficiency.The experimental results show that with the increase of air supply pressure,the nozzle air flow increases in the form of power function,while the water flow rate decreases in the form of exponential function,and the gas-liquid volume flow ratio increases continuously.The nozzle atomization angle and fogdrop droplet size decrease with the increase of air supply pressure,while the fogdrop velocity and range increase with the increase of air supply pressure.Under the water supply pressure selected in this experiment,the air supply pressure increases from 0.2 MPa to 0.7 MPa,the nozzle air flow increases by about 100 L/min,the water flow decreases by about 1.3 L/min,the atomization angle and the fogdrop particle size decrease by about 75° and 60 μm,and the fogdrop velocity and range increase by about 7.5 m/s and 210 cm,respectively.The full dust removal efficiency and respirable dust removal efficiency of the nozzle both increase first and then decrease with the increase of air supply pressure,and reach the maximum value under a certain air supply pressure.Different water supply pressures come with different air supply pressures for obtaining the highest dust removal efficiency.The air-water pressure combination with better atomizing and dust removal effect includes No.1(pL=0.2 MPa,pair=0.3 MPa),No.2(pL=0.3 MPa,pair=0.4 MPa) and No.3(pL=0.4 MPa,pair=0.5 MPa).The above air-water pressure combinations should be adopted in coal mine fields,which can obtain a relatively ideal fogdrop particle size and a higher dust removal efficiency with a lower water consumption.