Discharge Coefficients of Flat Fan Nozzles

Abstract

Abstract. The discharge coefficient, C d , is a measure of how much of the pressure energy of a nozzle is converted into kinetic energy. With the discharge coefficient known, the exit velocity of the liquid sheet from the nozzle can be calculated from the pressure. It is important to be able to accurately calculate this nozzle exit velocity for use in initializing computational simulations such as AGDISP or CFD. In this work we use a phase-Doppler interferometer to measure the exit velocity for standard, pre-orifice, and air-induction flat fan nozzles, or rated size from 01 to 06, at pressures from 1 to 6 bar. From these velocities discharge coefficients are calculated. The standard flat fans had the highest discharge coefficients, while the air-induction nozzles had the lowest discharge coefficients. For a fixed type of nozzle design, discharge coefficient increased slightly with rated flow rate. The discharge coefficient decreased slightly with increasing pressure for a given nozzle. Much of the differences in drop size from different types of nozzles can be explained by atomization theory as being a result in the differences in discharge coefficients from the different nozzle designs.