Abstract： To solve the problem of existing screw cores needing to be atomized at a high pressure, a screw core nozzle which could achieve the same atomizing performance at a low pressure was designed. Median diameters, velocity and spray cone angles of droplets at 1 m away from the nozzle were tested by a phase doppler particle anemometer with different screw core sizes and diversion diameters. The results show that the median diameters of the droplets caused by the nozzle are less than 100 μm with water pressures from 0.9 to 1.2 MPa, which proves the feasibility of the improved screw core nozzle. The greater the screw core size is, the less the median diameter and velocity are， and the greater the spray cone angle is.

Keywords: screw core nozzle; atomizing; droplet