The Effect Of Spray Rail On The Hydrodynamic Performance Of Planing Craft

As a kind of high-performance vehicle,planing craft has the advantage of high speed,which is an extremely distinct characteristic.Planing crafts can be used for patrolling,rescuing,fishing and other functions.Appendages properly attached to planing craft are ways to improve hydrodynamic performance.In order to analyze the effect of spray rail on the hydrodynamic performance of planing craft,computational fluid dynamics(CFD)method is used to calculate performance of planning craft sailing in calm water and in regular waves.And the effect of spray rails on the resistance and sailing attitude of planing craft is analyzed.Firstly,numerical method is used to calculate the process of two sections with different deadrise angles dropping into water,and numerical results are compared with theoretical results to verify the numerical results.Then,process of sections with different scales of 2D spray rails dropping into water are calculated,the results show that height of spray rails has significant influence on the lift force and changing of free surface during the process,but the width of spray rails' influence is not significant,and the influence of 2D sections dropping into water on the movement of planing craft.Secondly,CFD software STAR CCM+ is used to simulate process of planning craft sailing in calm water.Meshes with different quantities are calculated to obtain an efficient and accurate way of meshing;then resistance and sailing attitude of planing craft at multi velocities are calculated,the results are compared to experiment results and the empirical formula results,the results shows that numerical method can accurately calculate resistance and sailing attitude of planning craft sailing in calm water.Thirdly,performance of planing crafts with chine spray rails of different depths,lengths and installation locations and installation angles are calculated,the results are used to analyze the influence of these factors on resistance and sailing attitude,and then performance of chine spray rails is compared to bottom spray rails.The results show that by inhibiting splashing and adjusting trimming,resistance reduction of chine spray rails is good at the medium speed,while bottom spray rails has better resistance reduction at high speeds.Finally,numerical wave module of STAR CCM+ software is used to simulate the movement of planing craft in regular waves,the numerical results are in good agreement with experimental results.On this basis,the impact of chine spray rails and bottom spray rails onplaning craft are calculated,the results show that the chine spray rails can be used to reduce resistance and trim of planing craft in regular waves,while bottom spray rails are better at resistance reduction.