Experiments on the Mechanism of Unstable Phenomena during Self-Propulsion Test of Full Ship Model

Abstract

It was supposed that the origin of unstable phenomena during self propulsion test was the reverse flow and down flow induced by propeller near the upper and fore part of propeller aparture. The side force measurement and flow observation on a Lpp 2 m ship model were carried out in the circulating water channel, using the rotor or suction at propeller position induced the similar reverse flow and down flow, in order to confirm this supposition. As the result, the rotor or suction at propeller position made the similar flow and characteristics to unstable phenomena of self propulsion test. Therefore, it is thought that the origin of this unstable phenomena is the reverse flow and down flow induced by propeller, and the unsymmetrical effect of propeller is not necessary for the inception of this unstable phenomena.