Cavitation inception test on a systematic series of two-bladed propellers
Author G. Kuiper, T.J.C. Van Terwisga, G-J. Zondervan(MARIN), S.D. Jessup(DTRDC, USA), E.M. Krikke(Royal Netherlands Navy)
Title Cavitation inception test on a systematic series of two-bladed propellers
Conference/Journal 26th Symposium on Naval Hydrodynamics, Rome, Italy
Month September
Year 2006

Abstract
The paper aims at propeller design techniques which suppress inception of tip vortex cavitation. Model tests provide insight in the phenomena associated with tip vortex cavitation inception on propeller blades and the important parameters are systematically varied and investigated. The application of this work is primarily directed to improvements on naval propellers. However, lessons learned are also useful in the design of propellers for merchant ships, where there is a risk of cavitation hindrance due to vibrations or noise.

A systematic series of propeller blade designs has been made, based on an existing state of the art controllable pitch Naval propeller design. Geometric parameters were varied in the tip region including thickness, planform, skew, chord distribution and rake. All these parameters were varied while maintaining a constant radial loading distribution.

The results of the cavitation inception tests are presented in the form of inception diagrams for the distinct types of tip vortex cavitation that can be distinguished (trailing, local tip and leading edge vortex cavitation). Cavitation inception performance is quantified by the width of the non cavitating range of operating conditions at constant σ, referred to as the cavitation bucket. The systematic tests indicate that the blade contour is an important parameter in tip vortex inception.

Using the results of the systematic tests a series of propeller models were designed in an effort to improve the results further by combinations of the parameters in the systematic tests. As yet the results have shown no significant further improvements, but indicated the pitfalls and problems which have to be avoided. A low skew planform was finally designed aiming at the delay of cavitation inception. The model test results confirmed the design guidance derived from the systematic tests. Recent full scale observations confirmed the model test results and provide an illustration of the potential of the new design technique.

Panel Method analysis was used to assist in the design of the various tip variants. The possibilities and shortcomings in application of inviscid computations for the analysis of tip flow are shown.

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