Numerical Simulation of Unsteady Cavitating Flow in a Turbopump Inducer

Abstract

The unsteady cavitating flow in a turbopump inducer has been calculated using an accurate three-dimensional detached eddy simulation (DES) code, which took into account the cavitating phenomena. The three-dimensional code is based on the numerical method for compressible flow using low Mach number flow approximation. The cavitation is modeled by the source/sink of vapor phase in the liquid flow. The computational results were compared with experimental measurements: circumferentially averaged flow distributions at the inducer exit and visualizations. Qualitative good agreements with experiments were obtained. The unsteady motions of cavities have been simulated in the inducer. The magnitude of the fluctuation in cavity volume increased as the cavities extend and close to the throat of the blade passage. The effect of the tip-gap on the cavity volume was shown; the time-averaged volume of cavities for the inducer with the tip-gap is about five times larger than that for the inducer without the tip-gap at an operating condition. Vorticity generation in cavities due to baroclinic torque was found. This is a feature of cavitating flow. Multiple blade passages calculations are under way to find unsteady phenomena such as rotating cavitation and cavitation surge in the inducer.