Research On Hydrodynamic And Structural Response Characteristics Of Ultra-high Speed Trimaran Planing Boat

Fast performance of ultra-high speed trimaran planing boat is excellent,it can quickly reach the designated sea areas with fast response to events,so it has broad market demand.Trimaran planning boat has excellent fast performance and motion performance,always been a hot spot for new ship type research.Trimaran planning hull usually based on foreign parent ship for imitation in our country,understand of hull form essential mechanism and hydrodynamic performance is not deep enough.In addition,the high speed requires the hull structure to be lightweight,and with the speed increase,slamming load become the main load of high-speed ship,however,lack of the experience in design and construction of ultra-high speed hull structures with lightweight foam sandwich composites in our country,the research on the slamming response of the composite hull is not thorough enough,foreign research data also confidentiality.In this background,from the view of overall design,study for the key technologies of ultra-high-speed trimaran planning boat development,based on the hull form essential mechanism of the ultra-high speed trimaran planing boat on the hydrodynamic performance,using the sandwich composite material to carry out the maximum design speed of 75kn ultra-high speed trimaran planing boat structural design,Study on structural properties and slamming response properties of composites,the hull forming process was studied and the actual ship test was completed.This paper carried out the hydrodynamic performance of ultra-high speed trimaran planning boat by CFD method.Firstly,the influence of the longitudinal position of the gravity center the trimaran planing boat on its hydrodynamic performance is studied by ship model test.It is found that there are low-speed and high-speed resistance peaks in the longitudinal position of the trimaran planing boat,and the low-speed resistance peaks appear about at Fr▽=2.0.Study on the influence of hull form essential on hydrodynamic performance based on CFD incremental technology,reducing the height of tunnels could increase the working section length,which has more evenly distributed pressure under high speed than before.And it shows that the boat’s resistance increases with the width of tunnels under medium-high speed,which is not suitable for high-speed or ultra-high speed boat.For this reason,if the boat’s design speed is very high,the width can be appropriately increased.Therefore,the main body width has some effects on step and hydrodynamic performance.At last,it can be shown from the ship trial that the highest speed of the actual ship reached the highest design speed,and the hull exhibited good hydrodynamic performance and structural performance.Currently,it is the highest speed of ultra-high speed trimaran planning boat in China.Some studies on the sandwich composite structural design of ultra-high speed boat have been carried out.Design the sandwich composite structure with carbon fiber composite skin and foam core,analyzing the mechanical behavior of the structure,load calculation according to the specification,implementing the sandwich composite structure design and comparing its weights with those structures’ made of other materials at the same time.It shows that sandwich composite structures of carbon skins and foam core have excellent performance on structure strength and weight control.According to the maximum stress strength criterion and TSAI-WU criterion,failure analysis of structural response is made in two extreme conditions,structural design strength meet the requirements A numerical model of ultra-high speed boat under slamming load is obtained in the transient response analysis.Then calculate the slamming response of the ship structure.The vacuum assisted resin transfer molding(VARTM)process of the hull model was simulated,focusing on the flow of the resin filling process.Then,two molding schemes were proposed to simulate the upper surface of the sandwich.According to the filling flow results,a superior scheme was chosen.In the scheme,the main pipeline was laid in the middle axis,and the left and right diversion pipes were symmetrically laid.The scheme can effectively reduce the formation of dry spots and resin waste.In addition,a method for filling the lower surface of the sandwich was presented.