Film cooling and aerodynamic loss performance of turbine vanes with fan-shaped and wave-trenched holes

Experimental measurement and numerical simulation were carried out to study the film cooling and aero-dynamic loss performances of turbine vanes with cylindrical, fan-shaped, and wave-trenched holes. Tests were performed on a linear cascade. The mainstream inlet Reynolds number based on the vane chord length was 1.03 x 105, and three coolant local blowing ratios were conducted. A single row of film cooling holes was arranged in the acceleration region upstream of the pressure and suction surfaces of the test vanes, respectively. The effects of the hole shape and position of the hole row on the film cooling effectiveness and total pressure loss under various blowing ratios were comprehensively analyzed. Results show that on the pressure surface of the vane, at low blowing ratios, the film cooling effectiveness of wave-trenched holes is higher than that of fan-shaped holes. The wave-trenched hole exhibits obvious double peaks of the film cooling effectiveness. A pair of vortices and a coolant core are observed downstream of the trough wall and crest wall of the wave-trenched hole, respectively. At high blowing ratios, the film cooling effectiveness of them is comparable. On the suction surface of the vane, at low blowing ratios, the film cooling effectiveness of wave-trenched holes is lower than that of fan-shaped holes, and the trend is opposite at high blowing ratios. Two pairs of vortices are observed downstream of the crest wall of the wave-trenched hole. Wave-trenched holes have the highest shear stress rate and total pressure loss, followed by the cylindrical holes and fan-shaped holes at high blowing ratios. To the best of our knowledge, this is one of the few studies available on the systematic analysis of the film cooling and aerodynamic loss performance of turbine vanes with the three shapes of film cooling holes. The conclusions could provide effective guidance for the application of fan-shaped and wave-trenched holes during the elaborate design of film cooling structures on turbine vanes.