Cavitation erosion power

Abstract

With a view to a proper setting of hydraulic machines a hydrodynamic definition of the cavitation "intensity" is introduced independently of the blade material property.This definition is based on the observation that as far as severe erosion is concerned we may consider a corresponding development of a leading edge cavity on the blades of the runner.Blade erosion is due to the collapse of transient swirling cavities in the closure region of the main cavity.According to the generation process of these transient cavities a mean erosive power of the cavities is evaluated from the upstream velocity U-, the main cavity length 1 and the Strouhal number S of the fluctuation of the cavity.This definition leads to a term proportional to S U-312.The experimental data obtained from erosion, vibration and shock overpressure measurements tends to collapse to a single curve.However, these results make it possible to establish a procedure for predicting the erosion risk of the prototype units by using cavitation tests on the model. Cpwau Wall pressure coefficient (CVG)~