Scale adaptive simulations applied to fully cavitating turbulent flow in injector nozzles

Abstract

The unsteady and turbulent pressure-driven cavitating flow under fully cavitation conditions through a sharp-edged orifice is studied by numerical simulations. Unsteady cavitating flow is a typical flow configuration in fuels injectors and brings a challenge in the numerical modeling of two-phase fluid flows due to the high-pressure gradients involved and the high ratio of liquid and vapor density. Under this flow condition computationally intensive unsteady simulations are necessary to accurately simulate the irregular cyclic process of bubble formation, growth, filling by water jet re-entry and its breakoff. The capabilities of Reynolds Averaged Simulations are assessed to ensure a suitable cavity structure prediction to capture the main shedding frequencies and the vapor fraction variations along the nozzle. This study is focused on the performance of a modified version of the Shear Stress Transport turbulence model, involving a Scale Adaptive Simulations sub-model related to the unsteady turbulent flows modeling. The obtained results show that the proposed option would allow studies of developed cavitating flows by means of an unsteady Reynolds Averaged Simulation, computationally less expensive than the Large Eddy Simulations option, being this last option not completely affordable for simulating turbulent flows in industrial problems nowadays.