Study On The Characteristics Of Boundary Layer Flow Under The Influence Of Surface Microstructure

The energy consumption of a sailing body is closely related to the magnitude of it’s resistance.Research on the problem of drag reduction of the sailing body is of great significance to promote energy saving and emission reduction.Boundary layer control drag reduction is mainly achieved by controlling the coherent structure in turbulence and reducing its burst intensity and frequency.It can be divided into active control drag reduction and passive control drag reduction.In passive drag reduction,The advantages of the surface groove drag reduction are obvious.In this paper,the large eddy simulation method is used to study the boundary layer flow with triangular grooves and rectangular groove plates along the flow direction under subsonic and supersonic flow,and explore the influence of surface micro-groove structure on boundary layer flow.Simulation analysis shows that the triangular groove can block the fluid inside the groove,keep low-velocity fluid at the bottom of the groove,increase the thickness of the viscous bottom layer of the boundary layer,and reduce the velocity gradient at the wall.The spanwise stress component of the Reynolds stress in the triangular groove boundary layer is inhibited,the groove structure hinders the spanwise flow in the boundary layer,and the burst of turbulence on the wall is inhibited.In the subsonic range,the triangular groove can reduce the shear force by about 10%.At supersonic speeds,the flow vortex moves downwards into the interior of the groove,which will intensify the burst of turbulence.The rectangular groove has a weak blocking effect on the fluid in the groove,and can inhibit spanwise pulsation in the case of subsonic speed.The rectangular groove does not reduce the wall shear stress when the flow velocity is low,and even increases.When the flow velocity reaches supersonic speed,the flow vortex originally located above the groove moves downwards and enters the inside of the groove to induce a large number of secondary vortex.These secondary vortex in turn weaken the flow vortex,suppress the burst of turbulence,and reduce The wall shear stress is better than the triangular groove under supersonic speed,which can reduce the shear force by 13%.