Study On The Lift Force Induced By Interceptor

In this paper,model test and numerical simulation are adopted in the investigation on the viscous flow field of high-speed displacement ship with interceptor.The hydrodynamic mechanism of the effect caused by the interceptor is revealed,the influence of the feature parameters of the interceptor on the hydrodynamic force of the ship is studied,and the relationship between the ship form parameters and the lift force induced by interceptor is obtained.At last,a formala used to calculate the lift force induced by interceptor is presented based on the systematic analysis.It is found in the investigation that the lift force acting on the bottom of the ship with interceptor is caused by the vortex,which enhance the pressure of the flow field.The dimension of the vortex is determined by the height of the interceptor.The wave amplitude is increased by the interceptor,but an interceptor of optimized height is helpful in resistance reduction by increasing the "virtual length",optimizing the pressure distribution,improving ship attitude and hydrodynamic performance.It is shown in the investigation of the effect of various parameters on the lift force induced by interceptor that,speed and the height of interceptor are the dominating factors,meanwhile,draft,deadrise angle and trim angle are less important.The coefficient of the induced lift force is increased with speed and the height of interceptor,and the approximate relationship between them is quadratic function.The approximate relationships between the coefficient of the induced lift force and draft,deadrise angle,trim angle are linear functions.The lift force is increased with draft,especially at high speed.Deadrise angle and appropriate trim angle are helpful in enhancing the effect caused by interceptor,especially at low speed.The coupling effect of multiple factors on the lift force induced by interceptor is investigated based on the analysis of the relationship between each factor and the induced lift force.A formula in which the influence of each factor and the coupling effect are included is then presented to calculate the lift force induced by interceptor.Comparison of the results calculated by the present method and the mode test data indicates that much more accurate results can be obtained by the formula presented in this paper than the other literatures,especially for high-speed displacement vessels.