Research On The Characteristics Of Water Surface Traction Motion Of The Vehicle In High Sea Conditions

During the launch and recovery test in terrible ocean environment,the water surface traction link of the vehicle is highly important,difficult and dangerous.The stability of the water surface traction movement of the vehicle will affect the safety of the test process.During the operation of the traction system,the factors that affect the stability of the traction system include the hydrodynamic characteristics of the vehicle and the mother ship,the mechanical performance of the traction cable,the sea state level,the towing speed,the height difference of the traction mooring point,the length of the cable,the traction angle against wave,etc.Because of the complex interaction between the mother ship,the cable and the vehicle,it is difficult for the traction system to maintain a stable working state.This paper focuses on the research of the surface traction motion characteristics of the vehicle.The core contents are as follows:(1)CFD technology is used to simulate the vehicle in the viscous flow environment.The flow force coefficients,added mass and damping coefficients of the vehicle’s roll and pitch can be obtained through analysis and calculation.The flow force coefficients of the vehicle are basic parameter of the later time-domain analysis,and the damping coefficients of the vehicle’s roll and pitch which are calculated under the viscous flow environment can make up for the defect that the potential flow theory ignores the viscous damping.(2)Analyze the hydrodynamic frequency domain characteristics of the traction system using three-dimensional potential flow theory.Establish the hydrodynamic model of the traction system and conduct hydrodynamic calculations.With viscous correction based on CFD calculation results,this paper calculates the frequency domain hydrodynamic parameters of the vehicle and mother ship.Then compares them with the hydrodynamic parameters of the vehicle when the hydrodynamic coupling effect of the mother ship is suppressed.Thus,the hydrodynamic coupling effect of the traction system can be analysed.(3)The three-dimensional potential flow theory is used to conduct time domain simulation analysis on the traction system.Calculating the cable tension change of the traction system and the motion of the vehicle under different operating conditions,the specific impact to the traction system of various working conditions parameters are analyzed through the time-domain change curve.According to the change law of the cable tension and the motion of the vehicle,the appropriate value range of each parameter condition can be calculated.The research results of this paper are much valuable for the launch and recovery test of the vehicle in terrible ocean environment,which provide the possibility for the safe operation of the traction system under higher sea conditions.