Effects of Film Hole Exit Radiusing on Film Cooling Performance

In the present study, theoretical investigation of film cooling effectiveness and heat transfer behavior for radiusing of film hole exit was evaluated. Seven rounding radii of R=0.0D, 0.06D, 0.08D, 0.1D, 0.3D, 0.5D and 0.8D were investigated. The film cooling effectiveness, the heat transfer coefficient, net heat flux ratio and discharge coefficient were investigated. Four mass flow rates in the range of 0.00044: 0.0018[kg/s] were used to investigate the effects of coolant velocity on the film cooling performance. Results show that using the film hole exit radiusing helps in improvement the film cooling effectiveness. The radius of R=0.5D shows higher film cooling effectiveness among the other radii. The spatially average laterally film cooling effectiveness and net heat flux ratio of R=0.5D outperforms the case of R=0.0D at all mass flow rates except at higher rates the values are lower. Discharge coefficient of R=0.5D shows enhancement than R=0.0D with the pressure ratios. Interpretation of the low and high heat transfer coefficient regions for radii of R=0.5D and R= 0.0D depending on the flow structures was explained in detail.