Experimental study on the spray characteristics of low mass flow pressure swirl nozzles

Abstract Pressure swirl nozzles with small mass flow are severed as starting nozzles and their spray characteristics directly affect the ignition performance in the combustion chamber. In order to adapt to different combustion chambers and to clarify the spray laws of nozzles with different spray cone angles, experimental studies have been carried out on the spray cone angle, the breakup length, the droplet velocity field, and the droplet size distribution characteristics for two nozzles. The results show that with the increase in injection pressure, the spray cone angle increases and then tends to slow down, the liquid film breakup length and droplet size decreases, the droplet velocity decreases as the increase in axial distance, the droplet velocity decay rate of the outside of the cone is higher than that of the droplets at the center axis position. Under the same working conditions, as the spray cone angle increases, the sprayed droplet size decreases but its uniformity improves, and the droplet velocity near the center axis of the spray field of the smaller spray angle cone nozzle increases significantly. From a theoretical point of view, it is shown that the conical liquid film breakup length becomes smaller for nozzles with large spray cone angles at the same flow rates.