Research on Highly Skewed Propeller

Abstract

Authors planned theoretical and experimental research on Highly Skewed Propeller (HSP) in order to establish advanced HSP design method which enables remarkable decrease of vibratory propeller forces, high propulsive efficiency and no problem related to blade strength.First, simplified method to calculate wake adapted skew distribution and non-linear lifting surface method to estimate propeller open characteristics were developed. These outlines are presented in this paper.Then, propeller open test (1 st, 3 rd and 4 th quadrants), self-propulsion test and cavitation test (cavity extent and thickness) were performed by using following three propellers designed for a container ship.Convensional Propeller (CP) of MAU type (MPNO. 80-3) Convensional HSP (MPNO. 80-4) Theoretically designed HSP (MPNO. 80-5) (Wake adapted skew distribution is adopted, and blade section and rake etc. are determined from the result of non-linear lifting surface calculation in order to get high propeller open efficiency.) The test results obtained are as follows;(1) Thrusts of MPNO. 80-4 and MPNO. 80-5. at astern condition are lower than that of MPNO. 80-3.Propeller open efficiency and propulsive efficiency of MPNO. 80-5 at propeller design point are about same as those of MPNO. 80-3, even though propeller open efficiency of MPNO. 80-4 at propeller design point is about 2% lower than that of MPNO. 80-3.(2) The effect of skew on cavitation characteristics related to surface force (time variation of cavity volume) was quantitatively confirmed.This research continues.The sequent reports will inform the other model test results like measurement of pressure fluctuation on a hull and measurement of stress on propeller blade etc.