Abstract
As a step for clarification of the mechanism of cavitation erosion as well as noises at a jet-flow gate-valve, the cavitation-aspects and the associated sound-pressures were simultaneously observed systematically by means of high-speed-photography and sensitive pressure-detection through a hydrophone, in a 1/10-scale model-valve for various openings. We found the following three different types of cavitation, i.e. stringlike vortex cavitation (Type I), bubbly cavitation (Type II) in the jet shear layer, and induced cavitation (Type III). Each of them has its own desinent cavitation number as well as zone where cavities occur, and emits an impulsive pressure of special wave form. Especially for a narrower opening, the bubbly cavitation develops dominantly there emitting very high impulsive pressures, and the free jet is remarkably deflected downwards in the settling chamber, often touching the bottom, so that the valve will be heavily eroded.
