Simulation of the interaction between ship and ducted propeller with a modified body force method

Abstract

For ships with conventional propellers, the body force method is one of the main methods for self-propulsion research due to its high computational efficiency. However, when it comes to ducted propellers with complex internal flow fields, applicability of the body force method is still unknown. In this work, a modified body force method which can be applied to the ducted propeller is investigated. Specifically, the Reynolds-averaged Navier–Stokes (RANS) solver is adopted to simulate the interaction between a trawler and a ducted propeller. Before self-propulsion simulations, uncertainty analysis of ship resistance, ducted propeller thrust, and ducted propeller torque was carried out. As a comparison, the discretized propeller method and the body force methods are adopted in the simulations of self-propulsion. Because of the neglect of the duct, the errors of the conventional body force method exceed the allowable range. Therefore, the concept of the ducted virtual disk is proposed, in which only the propeller is replaced by the virtual disk. Especially, the advance speed coefficient and the open water curve of the virtual disk are modified, so that the open water result of the ducted virtual disk is consistent with that of the ducted propeller. The modified body force method has good accuracy and can roughly describe the wake fields when applied to self-propulsion simulation. Furthermore, the interaction between the ship and the ducted propeller can be well reflected, which is of great significance in rapidly predicting self-propulsion of ships with ducted propellers.