A Cavity Wake Model Based on the Viscous/Inviscid Interaction Approach and Its Application to Nonsymmetric Cavity Flows in Inducers

Abstract

A cavity wake model based on the flow interaction between the viscous wake behind the cavity and external inviscid cavity flow is proposed. The conditions of interaction between viscous and inviscid flows make it possible to obtain a unique solution of the problem. The viscous wake model is formulated within the theory of boundary layers. The problem for the external inviscid flow is considered in both nonlinear and linear formulation. The developed cavity wake model provides reasonable agreement with experimental data for cavitation performance and cavitation compliance over a wide range of cavitation numbers from cavitation inception to the super cavity flow. The cavity model is applied to predict nonsymmetric flows in inducers with two and more blades. The regions of nonsymmetric cavity flow are compared with those in experiments. It is found that the local head decrease of an inducer might be caused by the nonsymmetric cavity patterns. The predicted regions of a steady nonsymmetric cavity flow correlate with the region of cavitation instability observed in experiments.