Direct Numerical Flow Simulation in a Two-Dimensional Turbine Cascade

Using high order finite difference scheme,a Direct Numerical Simulation (DNS) of vortex shedding in a two-dimensional VKI turbine cascade has been carried out.The Reynolds number is 10 000,and the angles of attack are 0 deg,8 deg and -8 deg.The mechanism of unsteady flow in turbine cascade was investigated.Numerical results indicate that,near cascade trailing edge region,clockwise and anticlockwise primary vortices generate alternately from the surface.Secondary vortices form at the interactions of primary vortices and main flow.When secondary vortices mix with the main flow,primary vortices are divided and shedded from trailing edge.The changes of incidence in a certain range have no prominent influences on the development of blade boundary layer.The statistical characteristics and velocity defect characteristics in the wake region are also analyzed.