Analysis of underwater thruster model with ambient flow velocity using CFD

Abstract

Thrust force is a very important factor for underwater vehicles. The thrust force that is determined by the pressure gradient between a propeller and a thruster can be represented by the ambient flow velocity introduced as the control volume and the axial flow velocity of a propeller. Because a change in ambient flow velocity triggers a change in the pressure gradient between a propeller and a thruster, a model taking account of the ambient flow velocity is required for an unmanned underwater vehicle (UUV) system. However, the axial flow velocity introduced into a propeller is very difficult to measure without accurate test devices. Therefore, in this study, the axial flow velocity is calculated with the computational fluid dynamics (CFD) method to use it as a basis for estimating the approximate value of the thrust force. As a result, a relatively accurate analysis of the effect of the ambient flow velocity on the thrust force can be obtained with considerable time and cost effectiveness as compared to the existing experimental methods. To evaluate the validity of the data from the CFD analysis results depending on the change in ambient flow velocity and the pressure gradient of a thruster, the resulting CFD values were compared with the thrust forces obtained in the previously performed thrust force experiment of a thruster depending on the ambient flow velocity in a circulating water channel.