Abstract
Experimental and theoretical investigations on porpoising of a planing hull at high forward speed up to Froude numbers Fr = 6.0 (Fr = U √gL OA , where L OA denotes the overall length of ship) in calm water are conducted. Captive model tests and forced motion tests are carried out to measure the hydrodynamic forces acting on the hull. The results reveal that without any exciting force, such a craft can porpoise as a self-excited oscillation originating from the existence of coupling restoring coefficients of different sign in a coupled system. The results also show that significant nonlinear effects for motion amplitudes appear in the restoring, the added mass and the damping coefficients. The measured hydrodynamic forces are compared with the results of an existing prediction method including nonlinear effects, and show a good agreement with them. Simulation of porpoising in calm water is carried out using the predicted hydrodynamic forces in a nonlinear equation of motion. The calculated results are in fairly good agreement with experimental ones.
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Schedule a callMore From: Philosophical Transactions of the Royal Society of London. Series A: Mathematical, Physical and Engineering Sciences
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