Measurements of Cavitation Inception

Abstract

Some factors concerning the method of cavitation inception measurement are experimentally investigated. They are definition of cavitation inception, effect of air content, effect of methods of pressure change in cavitation testing and its rate of change. The test body is a circular cylinder in the flow range of subcritical Reynolds numbers, where cavitation bubbles occur in the separated shear layer behind the cylinder with a large scatter of incipient cavitation numbers. In the present work, one of the most effective definitions is proposed for cavitation inception and the following results are obtained using the proposed definition : (1) the inception values are greatly reduced in water with low air content of less than a critical value, (2) the inception point is affected by the pressure change rate under the condition of variable flow velocity. The uncertainty in cavitation inception measurement is also shown from a large number of measurements.