Improved body force propulsion model for ship propeller simulation

Abstract

Body force propulsion model has been used for ship self-propulsion CFD simulation for a long time due to its higher computational efficiency and less computer source required. This paper presents a new body force method coupled the blade element momentum theory (BEMT) considering the three-dimensional viscous effects with the RANS solvers. In-house code HUST-Ship was used to solve RANS equations with finite difference method and PISO arithmetic for propulsion model and ship hydrodynamic simulation. KP505 propeller and KCS ship model were used as the numerical model for the studies. Open water characteristics of discretized propeller model were obtained after uncertainty analysis of CFD results. The lift coefficients CL and the drag coefficients CD of different radius sections on the propeller blade were obtained from CFD results of open water characteristics. The multivariate regression method was used to get the correlations between CL, CD and propeller parameters for a propeller model. Then the BEMT method would adopt the correlations with the local velocity at the virtual disk from CFD simulation results simultaneously to calculate the thrust and torque distributions on the blade and thrust and torque of the propulsion model were obtained with integration along the blade. The comparisons of open water characteristics of CFD results between three different body force models and discretized propeller model were performed. The CFD simulation for open water characteristics and velocity distribution around propulsion models are almost same for new body force model and discretized propeller model. The self-propulsion simulations of KCS with new body force model were performed. The comparisons of the KCS self-propulsion simulations results with new body force model, discretized propeller model and EFD results showed good matches with each other.