Prevention of Cavitation in Propellers

Abstract

It is well known that cavitation phenomena affect the efficiency of propellers. It is a major world wide economic problem for the transport industry. The speed of fast, ocean going vessels is liimted by cavitation effects on hydrofoils and propulsion systems. The main approaches of industry to mitigate the detrimental effects of cavitation on propellers is restricted to varying operating conditions, geometric design and choice of wear resistant materials. We here develop a simple solution to the problem. It has been known for over a century that dissolved gases reduce the tensile strength of liquids by orders of magnitude. De-gassing of a iquid dramatically reduces the ability of a fluid to cavitate.  Propeller cavitation in ships and submarines is typically controlled by reducing rotation rate and/or blade pitch. We here demonstrate the astonishing fact that cavitation can be completely prevented by releasing de-gassed water adjacent to the low pressure side of a rotating propeller, without varying blade speed or pitch. Practical implementation is simple and cheap.