CFD based prediction on hydrodynamic effects of Interceptor and flap combination on planing hull

Abstract

It has been a continuous effort for long years by high-speed vessel designers to achieve its optimal hydrodynamic performance. Few studies were made on the impact of interceptor and flap combination on high speed hulls in recent years. Interceptors are blades which extend vertically downwards at the transom of the vessel and a flap is attached to its end. The installation of interceptor near the vessel transom a change in pressure distribution around the hull and more significantly observed at the transom. The present study investigates on the hydrodynamic quality of 20deg deadrise high-speed planing hull mounted with interceptor-flap combination using computational fluid dynamics (CFD). Planing hull model was analyzedusing CFD based Finite Volume method with dynamic mesh. The height of the interceptor and angle of flap plays an important role on the efficiency of the vessel. Experiments were carried out in the towing tank at Indian Institute of Technology Madras for the planing hull and CFD studies were extended with interceptor-flap. The validation studies serve to authenticate the use of the interceptor on the basis of comparison with simulations using model tests. The pressure variation that is caused due to integrated interceptor-flap has an effect on the resistance of the vessel which further showed better control of trim. The numerical study on planing hull with interceptor-flap showed an increased waterline length which leads to reduced Froude number. The hydrodynamically improved underwater form was observed leading to resistance reduction of upto 25% on the vessel and significant reduction of trim upto 57% at the design speed.