Numerical Study On Motion Response Characteristics Of Launch Ship Under Rocket Jet

In recent years,launching rockets at sea has increasingly attracted people’s attention.Due to its advantages in launching launch vehicles,it has attracted scholars’ attention.There are many scholars studying the rocket gas jet and ship motion response characteristics in these two fields,but there is less research on the relationship between the two.This article explores the motion response characteristics of launching ships under the action of rocket jets,and the following work has been done:In this dissertation,the pulse response function method and the Taylor expansion boundary element method are combined to analyze the seakeeping performance of the classic ship type Kvlcc2,including wave excitation force,time step,number of ship grids,Fr number and other parameters,and the results are compared with the experimental values.The results show that the calculated results obtained by the Taylor expansion boundary element method are consistent with the actual observation values,and can be used to predict the seakeeping performance of ships.Taking a certain type of launch vessel as the research object,analyze its motion response under different draft loading conditions;The numerical results indicate that the motion response amplitude of the launching vessel under a 5.0m draft condition is slightly greater than that under a 5.8m draft condition.In order to obtain the functional relationship curve of the pressure on the planar baffle during rocket thermal launch with time,Fluent was first used to analyze the two-dimensional axisymmetric Laval nozzle.The pressure on the planar baffle 72 mm and 110 mm away from the nozzle mouth was numerically calculated,and the results were compared with experimental values.The two results were in good agreement;Then the dynamic grid technology is used for numerical simulation,and the difference of the pressure on the plane baffle between the static grid computing and the dynamic grid computing under different distances is compared.The comparison results of the two are basically consistent,indicating the feasibility of using the dynamic grid technology for the numerical simulation of the rocket launch process.Using a certain type of rocket engine as a prototype,simplify its Laval nozzle and use dynamic grid technology to numerically simulate the motion of a two-dimensional single nozzle axisymmetric model during rocket launch.At the same time,monitor the function curve of pressure change on the planar baffle with time,and estimate the pressure on the planar baffle during launch.This article is based on the Fortran language modification and compilation of some source code developed by the R&D team related to technology.A certain type of launch ship is taken as the research object,and its motion response in waves is simulated in time domain.The impact of launch position,wave direction angle,and action phase on the motion response of the launch ship is evaluated and analyzed.The numerical results indicate that the lateral eccentricity of the rocket launch point relative to the projection point of the launch vessel’s center of gravity on the deck has a greater impact on the motion response characteristics of the launch vessel compared to the longitudinal eccentricity;Different wave angles have little effect on the motion response of the launching ship after rocket launch;Under the action of transverse waves,the rolling direction of the launching ship is more sensitive to the launch time.Choosing an appropriate launch time can reduce the amplitude of the motion of the launching ship after being subjected to impact loads.The above research can lay the foundation for short-term prediction of the impact of rocket launch on ships under complex sea conditions.