A potential flow theory and boundary layer theory based hybrid method for waterjet propulsion

Abstract

A hybrid method-coupled with the boundary element method (BEM) for wave-making resistance, the empirical method (EM) for viscous resistance, and the boundary layer theory (BLT) for capture of an area's physical parameters-was proposed to predict waterjet propulsion performance. The waterjet propulsion iteration process was established from the force-balanced waterjet-hull system by applying the hybrid approach. Numerical validation of the present method was carried out using the 1/8.556 scale waterjet-propelled ITTC (International Towing Tank Conference) Athena ship model. Resistance, attitudes, wave cut profiles, waterjet thrust, and thrust deduction showed similar tendencies to the experimental curves and were in good agreement with the data. The application of the present hybrid method to the side-hull configuration research of a trimaran indicates that the side-hull arranged at the rear of the main hull contributed to energy-saving and high-efficiency propulsion. In addition, at high Froude numbers, the "fore-body trimaran" showed a local advantage in resistance and thrust deduction.