The effects of shape and liquid properties on pressure swirl atomiser in-nozzle flow

The internal flow in pressure swirl atomisers (PSAs) is numerically predicted by performing large eddy simulations and using a volume of fluid approach. The output of the numerical model is validated by comparing it with three databases of experimental measurements obtained on large-scale PSAs available in the open literature. A simplified analytical model previously developed by the authors, which relate the swirl intensity to the thickness of the fluid exiting the nozzle, is used to analyse the flow behaviour in three PSAs, with large differences in the injector geometry, the operating conditions and the fluid thermophysical properties. This simple relationship is found to hold for the three PSAs, with small changes of the parameter that accounts for energy losses, while data obtained with relatively small variations of the injector geometry are found to collapse on the same curve. The effects of operating conditions and fluid thermophysical properties on this relation are found to be irrelevant.