Generalized Numerical Framework for Cavitation in Inducers

In this paper we present a capability to predict pump performance in cavitating flow regimes. Simulations of cavitating flowfields in a single-stage inducer type pump have been carried out. The pump used in this paper is the Simplex inducer geometry that has been extensively tested at NASA Marshall. We follow our turbomachinery simulations up with an extension of our cavitation model to cryogenic flow regimes, where temperature effects begin to play a significant role. Our framework encompasses an acoustically accurate, compressible multiphase model that has been previously validated. The model is implemented within a multi-element unstructured framework that permits efficient grids with locally high resolution near the cavitating zones and in the tip gap region. The pump simulations were performed at a fixed flow rate with different Net Suction Specific Speeds (NSS). The computational analysis indicates a strong correlation between performance loss and the extent of cavitation blockage, and accurately identifies the critical NSS number where breakdown occurs. Predictions of head loss compare well with experimental data. The cryogenic simulations were performed with liquid nitrogen flowing over a cylindrical headform. These simulations capture the essential features of cryogenic cavities such as saturation pressure depression close to the leading edge, and frothy nature of cavitating zones.