Study On Self-righting Performance Analysis And Optimization Method Of Water Jet Patrol Boat

In the 21 st century,human beings have entered a period of large-scale development and utilization of the ocean.With the country’s emphasis on marine development and the rapid economic and social development,the people’s interest and demand for offshore tourism have increased rapidly,and the density and frequency of offshore and inland river patrols by the maritime police and maritime affairs have also increased rapidly,and the demand for a large number of small ships has increased.,Small tourist boats,sightseeing boats,fishing boats,small private yachts,patrol boats,rescue boats and unmanned boats have sprung up.For these small ships,stability is the most important performance,especially the stability at large inclination angles.Once a small ship overturns in water at a large inclination angle,it will lead to serious maritime accidents and threaten the safety of people’s lives and property.If the ship will not overturn during the 0-180° heeling process and always have the ability to return to the upright state,the safety of small ships can be greatly improved,which is the selfrighting performance of the ship.In this paper,the self-righting performance of the ship is calculated and analyzed,and the optimization method of the self-righting performance is studied.This paper takes a 12.48 m small water-jet patrol boat as the research object.Based on the stability theory of large inclination angle and the ship’s rolling motion theory,the self-righting performance of the small water-jet patrol boat is calculated and analyzed.Self-righting performance in still water and waves,numerical simulation of its self-righting process,research on the main influencing factors of self-righting performance,secondary development of Maxsurf software based on Python,combined with genetic algorithm for small water-jet patrol boats Self-righting performance is optimized.details as follows:(1)Establish the 3D modeling of the small water jet patrol boat in Maxsurf software,calculate the stability of the small water jet patrol boat at large inclination angles,and obtain the small water jet patrol boat under different trim states of 0-180 in still water and waves °Static stability curve under the heel angle to analyze the self-righting performance of the small water-jet patrol boat.(2)The STAR-CCM+ software was used to carry out numerical simulation analysis on the self-righting process of the patrol boat in still water.Based on the overlapping grid technology,the numerical simulation experiment was carried out on the damping,rolling and free attenuation of the patrol boat during the self-righting process.The damping roll duration curve of the roll angle and roll moment was used to analyze the self-righting process of the patrol boat,and the safety duration envelope of the patrol boat self-righting was drawn according to the relevant specifications.(3)Analyze the main influencing factors of the self-righting performance of the small water-jet patrol boat,and use the control variable method to determine the longitudinal position of the center of gravity,the height of the center of gravity,the trim angle,the watertightness of the superstructure,the shape of the watertight upper structure and the displacement of the small water-jet patrol boat.The specific influence of the self-righting performance of the boat is studied,and the main direction of the self-righting performance optimization of the water-jet patrol boat is determined.(4)Based on COM specification,use Python language to carry out secondary development of Maxsurf software,expand the application scope of Maxsurf software,and run through the whole process from modeling to self-righting performance calculation through code;use genetic algorithm combined with secondary development to develop small water sprayers The self-righting performance of the patrol boat is optimized.The preliminary optimization enables the patrol boat to have self-righting performance in waves,and further optimizes the patrol boat to have better self-righting performance in still water and waves.