Boundary layer loss mechanisms of highly-loaded LP turbine blades

• 1、National Key Laboratory of Science and Technology on Aero-Engine Aero-Thermodynamics, Aero-Engines Simulation Research Center, Beihang University, Beijing 100191, China
• 2、Turbine Division, AVIC Shenyang Aero-Engine Research Institute, Shenyang 110015, China

Abstract：Numerical simulations of boundary layer flow of a highly-loaded low pressure turbine airfoil with different Reynolds numbers and freestream turbulence intensities (FSTIs) were carried out. The effects of Reynolds number and FSTI on the flow separation and transition were investigated. The results indicate that the total pressure loss at the cascade exit rises with a decrease of Reynolds number. The low Reynolds number causes the separation resisting ability of the boundary layer to diminish, and the flow separation loss to increase. Additionally, the friction loss of the laminar boundary layer increases as Reynolds number increases. The total pressure loss drops first and then rises with the increase in FSTI. This is because that the separation flow loss predominates at low FSTIs. The increased FSTI reduces the separation bubble size and, consequently, reduces the total pressure loss at the cascade exit. In contrast, at high FSTIs, the boundary layer friction loss predominates. The friction loss increases due to the increased FSTI, leading to the total pressure loss at the cascade exit.

Keywords： separation transition Reynolds number turbulence highly-loaded LP turbine