Effect of Air Injection on the Cloud Cavitation of a Hydrofoil

Abstract

This paper describes experiments investigating the effects of air injection on the cloud cavitation of an oscillating hydrofoil. The effects of continuous air injection were investigated using two different hydrofoils. Measurements of the acoustic pressure were made on the downstream test section floor and on the surface of one of hydrofoils, and the extent of noise reduction provided by air injection at various volume flow rates was determined. The acoustic surface pressure measurements were also correlated with visual observations made using high speed motion pictures of the cloud cavitation. Thus the effects of continuous air injection on specific cavitation structures could be identified. In addition, the effectiveness of pulsed air injection in achieving greater reductions in cavitation noise at volume flow rates equal to those used in continuous air injection experiments was investigated.