Numerical Study of the Impinging Jets Formed by an Injector with Different Nozzle Diameters

The collision of two or more liquid jets may provide considerable atomisation and efficient mixing of injected substances at the same time. This phenomenon is used, among others, in rocket engines, where the fuel and oxidiser are introduced separately and almost immediately mixed through self-impingement. Depending on the injection and operating conditions, diverse configurations of impinging jets are used, such as doublets, triplets, etc. The appropriately designed injectors and operating conditions ensure the short length of the liquid structures that are developed as a result of the jets’ collision, as well as lead to intensive atomisation. The following work presents a numerical analysis of some impinging jets with relatively high Reynolds numbers. Two different nozzle diameters were considered, which were designed for fuels with different calorific values and stoichiometric ratios. The work aims to investigate the influence of the nozzle diameters on the liquid jets’ interaction in the same nozzle arrangement (the same impingement angle and distance). The simulations were performed for the same liquid to exclude the influence of the liquid’s properties and conclude on the diameter’s effect alone. The injection pressure was the same in all of the cases. The calculations were made using large eddy simulation (LES) and volume of fluid (VOF) approaches. The simulation results indicated that the larger diameters enhanced the formation of waves in the liquid sheet that brought about the sheet’s disintegration and ligament formations.