Influence of periodic disturbances on inception of cavitation in sharp-edged orifices

Abstract

The influence of periodic flow disturbances on the onset of cavitation in sharp-edged orifices was determined through a series of experiments. Different amplitudes and frequencies of disturbance were introduced in the flow. The threshold value of cavitation parameter for which transition from attached to cavitating flow took place was shown to depend on the amplitude of the disturbance. Cavitating flow was initiated more spontaneously as the amplitude of disturbance increased. Hysteresis in the flow was, however, observed to decrease. Variations in the frequency of the disturbance did not bring about any significant change in the cavitation parameter at transition. The results are interpreted in terms of the available dwell time for cavitation and the characteristic residence time of the fluid in the sharp-edged orifice and in the pipeline upstream of the orifice.