Investigation of airfoil trailing edge heat transfer and aerodynamic losses

Modern gas turbine development is being driven by the often-incompatible goals of increased efficiency, better durability, and reduced emissions. High turbine inlet temperatures and ineffective cooling at the trailing edge of a first-stage stator vane lead to corrosion, oxidation, and thermal fatigue. Observations of this region in engines frequently reveal burn marks, cracks, and buckling. To better aid the designer of the turbine blade cooling scheme, the ability to model and predict the aerodynamic and thermal performance is required. A study of an actively cooled trailing edge configuration, in which coolant is injected through a slot, is performed. Computational results compare reasonably well with the experiments for blowing ratios of practical interest ranging from 1 to 4%. An optimum balance between maximizing blade row aerodynamic efficiency and improving thermal protection at the trailing edge is found at a blowing ratio of 2.8%. The thermal phenomena at the trailing edge are dominated by injection slot heat transfer and flow physics. Low-cost two-dimensional Reynolds-Averaged Navier Stokes (RANS) computations are found to be adequate for predicting the aerodynamic and thermal performance of gas turbine stator vane rows. These predicted trends are generally applicable over a wide range of gas turbine applications.