Numerical Simulation Research On High-speed Water Entry Impact

The problem of water entry of the moving body is very complex,involving the coupling of solid,liquid and gas phases.The research content is also diverse.The calculation of the impact load into the water was first proposed,and the research on the load characteristics has always been a problem of water inflow into the structure.In this paper,LS-DYNA explicit dynamics software is used to systematically study the load characteristics of high-speed moving bodies in water.The main research contents are as follows:A LS-DYNA-based numerical simulation method for high-speed water inflow is established.By adjusting parameters such as PFAC and NQUAD,the appropriate parameters were finally determined.The simulation and calculation of the vertical high-speed water entry of a typical moving body is performed.In the velocity range where the peak value of impact pressure do not reach the yield limit of the moving body,the elastic constitutive equation is used to study the parameters affecting the high-speed loading characteristics of the moving body.For different speeds,different angles,different angle of attack,four parameters of different head types are used to compare and calculate multiple operating conditions.The impact pressure peaks under different working conditions,the overall structural stress,the average pressure peak,acceleration and speed are analyzed.At the same time,the process of high-speed entry of the moving body under different free surface conditions is studied,and the impact pressure peaks,the overall structural stress,the average pressure peak,acceleration and velocity are analyzed.In the velocity range where the peak impact pressure exceeds the yield limit of the moving body,the plastic constitutive structure is adopted,and the stress and strain variation law of the high-speed moving body of the moving body is mainly studied.Firstly,three different models,rigid constitutive model,elastic constitutive model,and plastic constitutive model,are used to compare the speed of the moving body at high speed,and the advantages and disadvantages of the three different models are compared.Afterwards,the comparative calculations of the different constitutive speeds of the plastic constitutive structure are carried out to analyze the variation law of peak impact pressure,velocity acceleration,overall stress and average force,structural stress and strain,and flow field pressure.