Numerical Analysis of Stern Flap on Hydrodynamic Performance of Prototype Ship

Abstract

The effect of stern flap is numerically evaluated for a high speed slender vessel. The main parameters of the flap are chosen according to recommendations in relevant technical literature. The CFD analysis is performed using the SHIPFLOW modelling and analysis program. SHIPFLOW models the flow around the hull as nonlinear potential flow, calculating an equilibrium sinkage and trim from the integrated dynamic pressure. It computes wave resistance using either an integration of the pressures or a wave cut analysis, since the wave train produced by the ship is also a result of the calculations. The stern flap suppresses the wake behind the transom and alters the flow behind the stern. Comparison of SHIPFLOW CFD results for flap angles and their associated running trim and sinkage were made. Result of model tests conducted worldwide on optimum hydrodynamic design of stern flap suggests improved stern waves, increased propulsive efficiency and improved propeller cavitation performance.