A method for minimizing the occurrence of cavitation on propellers in a wake

Article type: Research Article

Authors: van Oossanen, P.

Affiliations: Netherlands Ship Model Basin, Wageningen, The Netherlands

Abstract: In this paper some indications are given as to how current propeller design practices may be modified to obtain improved cavitation properties for the moderately loaded screw propeller operating in a wake. Some general rules concerning the choice of propeller diameter, rotative speed, direction of rotation, blade area ratio, radial load distribution, etc. are discussed. The largest part of the paper, however, deals with a method to determine propeller pitch, blade thickness and camber in accordance with obtaining maximum latitude to variations in the angle of attack. It is postulated that for minimizing cavitation occurrence it is ineffective to determine pitch, thickness and camber solely by means of providing for the required strength, the required lift and a non-cavitating condition at shock free entry of the flow. The variation in the angle of attack, an inherent property of the non-uniform velocity field in which the screw propeller works, must also be accounted for. By incorporating the outlined quasi-stationary blade section shaping method in modern propeller design, the proper compromise between the conflicting characters of thick sections (with large possible cavitation-free angle of attack variations) and thin sections (free of cavitation at low cavitation numbers at shock-free entry of the flow) is made. This paper is a further development and another result of continuous and persistant research carried out at the Netherlands Ship Model Basin into the adaptation of the propeller to the wake to obtain optimum results.

DOI: 10.3233/ISP-1971-1820501

Journal: International Shipbuilding Progress, vol. 18, no. 205, pp. 321-333, 1971