Research On Numerical Prediction Of The Whole Process Of Water Entry Of Sliding Lifeboat

According to SOLAS Convention,all ships must be equipped with life-saving devices and required to carry out operation safety training.Free fall lifeboat is widely used because of its advantages of simple operation,fast release speed and good safety performance.It is of great significance to carry out research on the movement and load characteristics of lifeboat to ensure the life-saving safety of ship personnel in distress.This thesis uses the FINE/Marine platform,through the research on the numerical prediction method of the whole process of the dropping motion of the falling lifeboat,the influence of the initial motion parameters of the lifeboat on the attitude of the hull into the water is discussed,and the real-time numerical prediction model of the whole process of the motion response of the lifeboat sliding,entering the water and floating is constructed,finally the distribution characteristics and evolution law of the slamming load on the surface of the lifeboat are verified.The research results will provide reliable theoretical and technical support for the safety design of the sliding lifeboat and its release system and the development of the training simulator of the sliding lifeboat.The main research contents and achievements are as follows:Firstly,based on the model of the viscosity flow field of RANS equation and the coupled solution of the six DOF motion equation of the hull by overlapping grid technology,the realtime numerical prediction model of the whole process motion response of lifeboat with six degrees of freedom is constructed.A numerical prediction method is established to accurately describe the whole process of planing,dropping,entering water and floating,The slamming load,attitude change,motion response and free surface deformation of the lifeboat in the whole process of water entry are studied.At the same time,the movement of wedge into water is studied experimentally.The accuracy and effectiveness of the numerical simulation method are verified by comparing the numerical results with the experimental results.It lays a foundation for further research on the distribution and evolution model of slamming load of lifeboat.Secondly,on the basis of the numerical prediction calculation method,the motion equations of the lifeboat in the process of sliding and dropping along the track are solved by the self programming,and the calculation results are shown in the form of charts;At the same time,the numerical prediction of the whole process of the lifeboat into the water is carried out by stages.The influence of the length,inclination angle,end height of the slipway,the center of gravity of the hull,the different speed and angle of the water into the lifeboat on the throwing and entering into the water is found out,and the quantitative analysis model of the initial conditions and parameters of the lifeboat into the water is established,the motion response characteristics of the hull in the water entry process are verified.The escape performance of the glide down lifeboat with different parameters was comprehensively evaluated.Finally,based on the numerical calculation method of the water entry movement of the lifeboat established in this thesis,the evolution law of the slamming load is explored by arranging pressure monitoring points on the surface of the hull;the influence characteristics of the water entry speed and angle on the slamming load peak value of the sliding lifeboat are analyzed qualitatively and quantitatively;the distribution law of the maximum slamming pressure load on the hull surface is explored;Based on the water entry theory,the maximum slamming force coefficient under different water entry velocity and water entry angle is calculated,and the distribution curve of the maximum slamming force coefficient along the ship length is fitted.