Influence of hole angle and shaping on leading edge showerhead film cooling

Detailed film cooling measurements are presented on a turbine blade leading edge model with three rows of showerhead holes. Experiments are run at a mainstream Reynolds number of 19,500 based on cylindrical leading edge diameter. One row of holes is located on the stagnation line and the other two rows are located at +/- 15 degrees on either side of the stagnation line. The three rows have compound angle holes angled 90 degrees in the flow direction, 30 degrees along the spanwise direction, and the two holes on either side of the stagnation row have and additional angle of 0 degrees, 30 degrees, and 45 degrees in the transverse direction. The effect of hole shaping of the 30 degrees and 45 degrees holes is also considered. Detailed heat transfer coefficient and film effectiveness measurements are obtained using a transient infrared thermography technique. The results are compared to determine the advantages of shaping the compound angle for rows of holes off stagnation row.. Results show that, the additional compound angle in the transverse direction for the two rows adjacent to the stagnation row provide significantly higher film effectiveness than the typical leading edge holes with only two angles. Results also show that, the shaping of showerhead holes provides higher film effectiveness than just adding an additional compound angle in the transverse direction and significantly higher effectiveness than the baseline typical leading edge geometry. Heat transfer coefficients are higher as the spanwise angle for this study is larger than typical leading edge geometries with an angle of 30 degrees compared to 20 degrees for other studies.