Analysis Of Ship Motion Response During Marine Rocket Recovery Under Impact Load

China has formed a complete maritime satellite launch system.The first stage rocket after launch will be reused in the later stage to improve the economy of commercial satellite launch.Currently,China’s offshore rocket recovery technology is still in the verification stage and there are also many key technologies that have not been resolved,such as motion response analysis of recovery ship,numerical prediction of impact loads and analysis of factors affecting recovery accuracy.Based on these issues,this article conducts research on motion response analysis of rocket recovery ship under impact loads.The overall goal is to establish a coupled motion analysis method for ship during the offshore rocket recovery process,Find out the key factors that affect the accuracy of offshore rocket recovery,Avoid adverse factors in advance to meet the technical index that the extreme value of hull motion is less than ±3° under recovery conditions.Therefore,the research object is a certain type of rocket engine and marine rocket recovery ship,Based on the CFD software STAR-CCM+,the impact load characteristics of steady and unsteady state gas jet are analyzed.Starting from the steady-state results of high-temperature and high-speed compressible gas jet under different turbulence models,the static pressure ratio of baffles and the structure distribution of jet wave under four different conditions are discussed.The numerical simulation method is verified by comparing with physical test;Then,based on the parameters of actual rocket nozzle and combustion chamber,the unsteady process of rocket falling back is further considered,the impact load on deck of rocket during vertical landing stage and the time history of total pressure at some monitoring points are studied,and the influence of different combustion chamber pressures on the structure and magnitude of impact jet wave during dynamic landing process is discussed,and the expression method of impact load for the whole process of marine rocket recovery is obtained.The CNT-TEBEM potential flow solver based on the three-dimensional Taylor expansion boundary element method is used to complete the frequency domain hydrodynamic performance analysis of recovery ship,including wave making damping coefficient,additional mass coefficient,and six degrees of freedom RAO.Taking a single point mooring FPSO hull as an example,the accuracy of the CNT-TEBEM potential flow solver is verified by comparing the results with ship model tests and commercial software Aqwa;A computational model for analyzing the motion response of recovery ship under the coupling action of impact load,hydrodynamic force and mooring force is established in time domain.The effects of key factors such as wave parameters,rocket landing point,mooring parameters and impact load action time on the ship’s motion state are discussed.A comparison of time history curves with commercial software Aqwa and physical test verifies the reliability of the time domain solver,The conclusion can lay a solid foundation for the establishment of operational conditions standards for marine rocket recovery in China and provide data reference for the subsequent implementation of marine rocket recovery tests in China.