Respective effect of waterjet suction and jet action on hull resistance

Abstract

Waterjet suction and jet action have their own effect on hull resistance. It is generally hard to quantify their respective roles on changing hull resistance through the model tests and conventional numerical simulations. Apart from the bare hull and self-propelled hull, this paper introduces another three intermediate self-propelled hulls with overall waterjet action, single suction and single jet action respectively through numerical simulations. Combined with model test, this paper conducts numerical investigations on the respective effect of waterjet suction and jet action on resistance in a wide speed range of 0.68 <Fr▽ < 6.16. At low speed, it is the jet action of waterjet that plays the dominant role on influencing the earlier critical Froude number of transom clearance of self-propelled hull, while the waterjet suction has little effect on it. At semi-planing and planing states, the variation of pressure and shear stress acted on aft-hull is majorly influenced by waterjet suction, which dominants the local effect (flow field change) and global effect (hull attitude variation) on resistance at the same time. This work is helpful to explore further understand on hull-waterjet interaction and provide more detailed instruction on design of waterjet-propelled planing crafts.