The cooling performance of three-row compound angle holes on the suction surface of a rotating turbine blade

Abstract

Experiments were carried out to study the effects of compound angle, hole arrangement, and blowing ratio on the film cooling performance of multiple rows of holes on the suction surface of a turbine blade. The turbine worked at rotational speed of 600 rpm corresponding to the rotational Reynolds number of 5.36 × 105. Three rows of cylindrical holes arranged in line or in stagger were drilled on the rotor blade suction surface at the streamwise location of 12.4%, 17.8%, and 23.2%, respectively. Three compound angles, with the same streamwise angle of 45° but different lateral deflection angles of 45°, 0°, and −45°, were studied. The film cooling effectiveness was obtained using pressure sensitive paint (PSP) technique with average blowing ratios varied from 0.5 to 2.0. The results showed that the application of compound angle changes the jet direction in the near-hole region and makes the film spread laterally. Compared with the film cooling without compound angle, using positive and negative compound angle can improve overall average film cooling effectiveness by about 20% and 25%, respectively. The effects of the secondary flow also can be weakened. A stagger film trajectory arrangement can achieve more uniform film coverage with higher overall film cooling effectiveness. The film trajectory arrangement of a positive compound angle injection is determined by the combined effect of hole arrangement and blowing ratio. While, the film trajectory arrangement of a negative compound angle injection is almost the same as the hole arrangement and nearly does not change with the blowing ratio.