A total three-dimensional evaluation method to analyze the loss mechanism of film cooling on turbine guide vane

Abstract

In view of the situation that the secondary flow in the passage deflects the coolant from film cooling holes and changes heat transfer, a total three-dimensional evaluation method is developed based on the HS1A high-pressure turbine guide vane to take a new insight into the loss mechanism. Film cooling holes are placed on the suction surface with compound angles to obtain different blade models. After satisfying the requirement of film cooling effectiveness, TTDM, a new total three-dimensional evaluation method where both mainstream and coolant are treated in three dimensions is established. Then, loss mechanism is analyzed by controlling the temperature ratio, changing the exit Mach number and blowing ratio. The entropy creation due to mixing is used as the evaluation basis to analyze different models within the high film cooling effectiveness range. It is believed that the mixing temperature and velocity need to be elaborated and distinguished in high subsonic environments. Compared with the original model within a certain range, the increase of the film cooling effectiveness can be found under the application of different compound angles in a short distance on suction surface. A slight increase of entropy is also noticed. By lessen the loss of secondary flow within a certain range of blowing ratio and exit Mach number conditions, the total loss can be reduced with reasonable setting of compound angle. Finally, the loss with film cooling is evaluated more accurately by the total three-dimensional evaluation method considering the effects of secondary flow.