Experimental and numerical investigation of the propeller thrust reduction in bollard pull condition

Abstract

The polar ships are often in bollard pull condition, which is prone to induce propeller cavitation and cause thrust reduction, weakening the ship’s ice-breaking ability. Based on the model tests and numerical simulations, this paper aims to investigate the propeller thrust reduction in the bollard pull condition. Firstly, the test of a self-designed ice class propeller under different cavitation numbers is carried out. The thrust reduction phenomenon is successfully captured and the hydrodynamic characteristics are obtained. Subsequently, the simulation based on Star-CCM+ is performed. It is found that the propeller thrust decreases almost linearly after the cavitation number reaches a certain threshold. When the cavitation number is equal to 0.25, the thrust decreases to 38.1% of that in the open water condition. By analyzing the mechanism of thrust reduction, the main reason is recognized that the average pressure of the blade face decreases greatly due to the influence of the cavitation on the blade back.