Counter-rotating streamwise vortex formation in the turbine cascade with endwall fence

The three-dimensional turbulent flows in the turbine cascade with and witho ut endwall fences are numerically investigated by solving the incompressibl e Navier-Stokes equations with a high-Reynolds number k-epsilon turbulence closure model. The limiting streamline patterns and the static pressure con tours at the suction surface of the blade as well as on the cascade endwall are employed to visualize the effectiveness of the endwall fence for the s econdary flow control. The analysis on the streamwise vorticity contour map s along the cascade with the three-dimensional representation of their iso- surfaces reveals the complicated structures of the vortical flows in the tu rbine cascade with endwall fence, and also leads to an understanding on the formation of a counter-rotating streamwise vortex over the fence. The mech anisms of controlling the secondary flow and the proper selection of an opt imal fence height are also explained. (C) 2001 Elsevier Science Ltd. All ri ghts reserved.