Parametric Study of Showerhead Film Cooling Performance on a Gas Turbine Blade

Gas turbine power and efficiency have direct relation with inlet gas temperature. However, high gas temperature could cause thermal damage to gas turbine blade material. Gas turbine blade could be cooled using the so-called film cooling technique which is necessary to ensure blade material integrity. In film cooling, air from compressor is injected through internal blade ducts. The air leaves the internal ducts through holes placed on blade surface, creating a cooling film on the blade surface. Operating conditions and hole geometrical factors can influence the cooling effectiveness. Several investigations have been conducted related to film cooling in order to study its behavior under different conditions. Due to its complexity, many studies replace blade geometry for flat plates. A better approximation to realistic results could be obtained by modeling the blade geometry with cooling holes. In this work, influence of geometrical parameters on cooling effectiveness under different operating conditions, like blowing ratio and angular velocity, is studied by means of numerical analysis using a commercial CFD code. The object of study is a typical showerhead configuration at mid-span of the tested blade, with three rows of cooling holes. In order to reduce computational cost, an algorithm was implemented to generate blade geometries and grids, performing numerical analyses and computing results in an automatic way, based on selected parameters. The algorithm could be used in optimization process to reduce the effort used in the construction geometries. The results show the effects of change geometrical parameters on cooling effectiveness. Additionally, changes on cooling flow direction are observed at high angular velocities.