Turbomachinery

Three-dimensional numerical investigations were conducted for the internal flow of the rear stator cascade of the diagonal flow fan. Corner separation near the hub surface and the suction surface of the stator blade are focused on. At low flow rate of 80％ of the design flow rate, the corner separation between the suction surface and the hub surface can be found in both experimental and numerical results. Separation vortices are found in the limiting streamlines on both the suction and the hub surfaces at 80％ of the design flow rate in the three-dimensional numerical simulation.

View full abstract

Show abstractHide abstract

This paper presents experimental results on bypass transition of the boundary layer on the low-pressure turbine airfoil, and examines the sensitivity of this transition process to freestream turbulence and Reynolds number. Hot-wire probe measurements are performed on the suction side of low-pressure linear turbine blades at three Reynolds numbers and three levels of freestream turbulence conditions. The results of this experimental study show that the location of boundary layer separation does not strongly depend on the freestream turbulence level. However, as the freestream turbulence level increases, the size of separation bubble becomes small and the location of turbulent transition moves upstream. The size of separation bubble becomes small as Reynolds number increases. At freestream turbulence intensity of 1％, the velocity fluctuation due to Kelvin-Helmholtz instability is observed clearly in the shear layer of the separation bubble.

View full abstract

Download PDF (174K)

Register with J-STAGE for free!