The Influence Of Pontoon Shape On The Motion Performance Of Offshore Satellite Launching Platform

With the development of comprehensive utilization of marine space in China,rocket launcher combined with land-based launch vehicle has many disadvantages,such as potential safety hazard,high service cost,poor launch mobility and so on.In order to meet the launch requirements of civil,commercial and other launch,it is urgent to expand a new launch mode of launch vehicle—marine satellite launch.Considering the complexity and sudden changes of marine environment,in order to improve the overall safety and reliability of marine rocket launch,we need to carry out relevant research on the marine launch technology of satellite launch vehicle,including the selection of marine satellite launch platform,the optimization design of main body,and the impact of the rocket on the launch platform during the launch process.Based on the viscous flow theory,this thesis analyzes the dynamic response of offshore satellite launch platforms with different pontoons by using the CFD commercial software STAR-CCM+ fluid analysis module,the contents are as follows:(1)Firstly,the related literature domestic and oversea is reviewed,and the research status of numerical wave tank is analyzed.On this basis,the development status of offshore platform,the research progress of offshore satellite launch platform and the motion response of semi-submersible platform are summarized.(2)Based on the theory of hydrodynamic analysis,the theory involved in this thesis is described.The basic governing equations of fluid motion,the advantages and disadvantages of various turbulence models,the boundary conditions and initial conditions,the treatment of free surface,the overlapping mesh technology and Six-DOF rigid body motion are introduced.(3)An efficient three-dimensional numerical tank is established to meet the functions of wave making and wave elimination at the same time,and the convergence analysis is carried out for the influence of the spatial division on the mesh,the time step and the length of the wave-eliminating zone.Finally,the appropriate grid size,time step and the length of wave elimination zone are obtained,and the numerical simulation results are compared with the theoretical values to verify its accuracy,which lays the foundation for the follow-up research.(4)Taking the parent semi-submersible platform as a hypothetical satellite launching platform,four kinds of launch platforms with different pontoon shapes are established,and the motion responses of them in different wave directions are analyzed.According to the numerical results,the motion response and column wave run-up of different pontoon shapes platforms are discussed,the wave run-up law of the front and rear columns of the launch platform is studied.The influence of pontoon shapes on the motion responses,wave run-up and wave surface distribution in column group is analyzed,the results can provide a reference for the selection of pontoon shapes of the subsequent marine satellite launch platform.(5)Based on the above research conclusions,the user-defined function editing function of STAR-CCM+ fluid analysis module is used to compile steady and unsteady impact loads,so as to simulate the thrust reaction during the launch process of the rocket on the launch platform,and the motion responses of the offshore satellite launch platform under two kinds of impact loads are analyzed respectively: the motion response of different shape of pontoons and the waveform distribution among the columns of the platform are analyzed in still water conditions;the motion response of the marine satellite launch platform under different sea conditions under two kinds of impact loads in different sea conditions is discussed,and the influence mechanism of different shape of pontoons on the motion performance of the marine satellite launch is summarized;the wave surface around the front and rear columns of the launch platform under the two kinds of loads is compared and analyzed,and the wave variation law around the column of the launch platform during the launch process of the offshore launch vehicle assumed in this thesis is obtained.