Experimental Study On Single Point Moored Vessels Subjected To Typhoon

Anti-typhoon Single Point Mooring system is mainly used in our country. It is mostly designed by empirical formula at present. Numerical model and experimental test is used to study the mooring force of Single Point Mooring System (SPMS).A numerical model in time domain is used to predict the dynamic responses of SPMS subjected to wind,wave and current. The model is established under the study on the achievements of Single Point Mooring Systems and rises of oil drilling platform. The nonlinear five-order Stokes wave is employed to predict the wave load of SPMS in the model, and second-order wave drift forces are also considered by taking into account of the square item in Bernoulli equation. Based on the Hamilton-type quasi-variation principle, a method is used in this paper which applying the quintic B-spline function as interpolation to the time sub domain. A formula named Quin which is applied to compute the mooring force of strait and long vessel is picked out, after computing the force of four kinds of vessels by numerical model and six empirical formulas in the presume environment.In the experimental test, the scales of vessels,cable and the speed of wind are confirmed based on Froude number similitude. Parameter such as wind coefficient and current coefficient in it is confirmed by experimental test. The law of movement and load of Anti-typhoon SPMS subjected to wind,wave and current is study by experimental test, the effect and degree of which is analyzed. In the end a empirical formula which is suitable to compute the mooring force of strait and long vessel is presented.Based on the results of experimental test, We found that the force of mooring subjected to wind compound current is larger than the force subjected to wind and current. Coupling effect occurred when SPMS subjected to wind compound current. Coupling effect coefficientμis introduced based on Quin formula, and found the well relationship ofμand the ratio of up water of vessel area and down water of vessel area (Au/Ad).