Study on Synchronous Effects of Free Surface and Propeller Rotation on Vessel Rudder Force

The paper presents a theoretical foundation of the effects of free surface and propeller rotation on the flow surrounding the rudder of a vessel. This is the scientific ground to evaluate the instability of the rudder force, thence building a research model and applying CFD in simulated to calculate the phenomenon. On the other hand, this paper also issues the idea of designing and creating a test system for carrying out practical experiments on related problems by using ship models similar to M/V TAN CANG FOUNDATION. The input data merely including ship's lines, ship's speed, rudder angle... are observed in the period of manoeuvering the vessel in the Haiphong fairway, Vietnam. The results are shown in this article distinctly figure out pulsating air bubbles caused by the synchronous effects of the free surface, the propeller rotation and indicate that the oscillating period of the rudder force at the time cavitation at the leading edge of the rudder which has not been formed is compatible with the revolutions of the propeller.