Design And Mechanism Analysis Of Underwater Drag Reducing Members In The Shape Of The River Raft

With the developing of social and science,people are paying more and more attention to the non-renewable energy,how to reduce or avoid to consume the non-renewable energy has became a public problem of human.This article mainly discusses the common ship surface drag reduction technology of bionic non-smooth surface drag reduction technology were studied.Inspired by The migratory features of puffers and combined with the study of surface properties of puffers surface non-smooth characteristic,building imitation puffers spines surface structure and applied in the field of fluid drag reduction.Study the effect of features spines morphology characteristic and size parameters of underwater drag reduction.The specific research content is as follows:(1)Combining with the relevant theory to determine the dimensions of the imitation puffers spines unit size parameters,at the same time determine may affect the drag reduction effect of related factors.Through the appropriate orthogonal table of numerical simulation of orthogonal experimental design.To establish the calculation area and its discretization,for nearly wall grid using special treatment.(2)The method of selecting numerical simulation is The Reynolds Average Numerical Simulation,turbulence model is RNG model,the wall surface method is the wall function method,the discrete method of control equation is the Finite Volume Method,the discrete format is Second Order Upwind Scheme,the flow field numerical solution is SIMPLE format,determine the boundary conditions and initial conditions,at the same time do some measures in order to ensure the calculation precision.(3)Through the calculation of numerical simulation,the simulation results corresponding to each group test of drag reduction rate.The test group with the best reduction resistance in the orthogonal table was group 3,with a reduction of 3.80%.The main order of the effect of the reduction in the effect of the reduction was obtained by the analysis of the extreme difference: A > B > C > D > E,and the combination with the best reduction resistance was A1B1C3D2E3.Factors variance analysis index A,B and C for the effect of drag reduction effect conjecture is significant,and the factors influencing index D and E for the effect of drag reduction effect conjecture is not significant.(4)By analyzing the wall shear stress,flow speed and drag reduction unit factors,such as peripheral velocity vector for underwater bionic drag reduction on the surface of the drag reduction mechanism of drag reduction unit is hindered by the body fluid,the fluid flow around on both sides from drag reduction,in drag reduction unit surface boundary layer,due to the viscous effect between the fluid to keep fit.The internal flow of fluid in the boundary layer is affected,and the flow velocity of the internal fluid of the boundary layer is decreased,and the boundary layer is separated.After the separation of boundary layer fluid velocity within the small and unstable,gradually formed "whirlpool","whirlpool" rolled along the surface towards the top from the bottom of the drag reduction unit,due to the speed and flow rate on the contrary,finally realizes the drag reduction effect.