Invstigations of cooling air position on turbine aerodynamic loss

The application of film cooling in aero-engine turbine for the purpose of thermal protection inevitably results in aerodynamic loss. This paper presents a study investigating the influence of the cooling air position on the aerodynamic performance of the turbine cascade, employing both experimental and numerical methods. A methodology for loss decomposition is proposed based on the development phases of film cooling loss. The following conclusions are reached: the aerodynamic loss induced by film cooling can be divided into three categories: the mixing loss between the cooling air and the mainstream(ξ1), the boundary layer loss induced by cooling air(ξ2), and the wake mixing loss (ξ3). When the film cooling hole is situated on the pressure side, the cooling air result in a low aerodynamic loss, which is primarily attributable to the mixing between the cooling air and the mainstream. When the film cooling hole is situated on the leading edge or suction side, the cooling air induces boundary layer transition, resulting in significant boundary layer loss. The boundary layer loss induced by the cooli ng air is the primary reason for the notable discrepancy in the film cooling loss at different positions in the turbine cascade.