关键词: 流场测量;转捩与分离;边界层;低雷诺数;涡轮

Abstract: The flow field characteristics and its control under Low-Reynolds numbers work condition are essential for the Aero-Engine Low Pressure Turbine design. An experimental investigation was conducted on the turbine cascade flow field with the low-Reynolds numbers. The separation and transition of the boundary layer on the suction side of turbine blade were investigated with the special oil flow display, surface static pressure holes, and boundary layer pressure probe. The detailed measurement results for the turbine cascade outflow field and blade surface boundary layer were presented. The results show that the flow losses increase with the decrease of Reynolds number, and a critical Reynolds number is in existence. When the Reynolds number is less than this critical value, the flow separation occurs on the suction surface with an open laminar separation bubble, and flow can not reattach. When the Reynolds number is larger than the critical value, the separated flow reattaches before the blade trailing and a closed separation bubble is formed. As the Reynolds number decreases, the exit wake is broadened, while exit flow loss and exit velocity deficit,as well as exit flow angle departure increase. Meanwhile the center of the wake shifts away from the suction surface. 

Key words: Flow measurement;Transition and separation; Boundary layer; Low-Reynolds number; Turbine