The Added Mass Research In The Process Of Ship Collision

Ship collision is a typical fluid-structure interaction problems.Ships collide with each other produce the rigid motion response at various degrees of freedom as a result of the instantaneous collision force caused by ship collision which causes the change of fluid environment.This change in return put an effect on the movement and deformation of ships,which causes the fluid-structure interaction effect between ships and the surrounding water.In this situation,the fluid involved in energy absorption by doing work to the moving ships.Therefore,to find an effective way to describe the influence of fluid around the ships is the most difficult problem.The research object of this article is the surrounding fluid of collision ships,which regardless of the fluid viscosity,only considers ideal fluid in the process of calculation.First of all,the cause of added mass and damping coefficient were discussed in this paper by combination with the basic equation of collision motion of the ship;next,common used calculation methods of the added mass during ship collision were discussed;then,the added mass of single moving ship was calculated in which the initial velocity,acceleration,fluid types and relative position were taken into consideration;finally,a model considering fluid constant resistance and fluid inertia force for calculating the added mass was given based on simulation.In this paper,the main research work is as follows,(1)The concept of added mass and development are put forward.The mechanism of formation of the added mass and fluid damping were analyzed in combination with additional quality theory and the basic equation of collision motion.(2)The calculation method of additional mass in the collision problem.The traditional theory calculation method of additional mass,empirical formula and slicing theory for example,were introduced.The simulation method of CFD was also introduced whose reliability was verified by the author;(3)Under the initial velocity of single ship natural motion response is analyzed.The added mass calculation method and law of motion of single moving ship under the situation of surge and sway motions in different initial velocity,acceleration,fluid types and relative position were discussed.(4)The applicable scope of the empirical formula were discussed,and a new model of the added mass was put forward.Additional mass model and the fluid-structure interaction model based on empirical formula was compared to each other under different collision model.The limitations of empirical formula were discussed,a new model considering fluid constant resistance and fluid inertia force for calculating the added mass was given which can reduce the fluid impact in parallel collision.