Effect of blowing ratio, rotation, and film hole row location on film cooling on the suction surface of a rotating turbine blade

Experiments and simulations were performed to study the single-row film cooling performance on a turbine blade suction surface. Effects of blowing ratio, rotation, film hole row location, and the combine effects of the above three factors on single-row film cooling performance were studied. Totally three injection row locations of 12.4% S, 23.2% S, and 34% S were taken into consideration, where S refers to the suction side streamwise length. Experiments were carried out under turbine speeds of 400rpm, 600rpm, and 800rpm respectively with average blowing ratios change in the region of 0.5 to 1.5. Rotational Reynolds number corresponding to the turbine speeds was 3.57 × 10⁵, 5.36 × 10⁵, and 7.15 × 10⁵. Pressure sensitive paint (PSP) technique was employed in obtaining film cooling effectiveness distribution. To assist explain the experimental results, numerical simulations were performed to acquire the mainstream and coolant jet flow field and local blowing ratio of each film hole. Results showed that film traces on the suction surface are bent toward the blade mid-span, and the downstream jet deflects more. Increasing blowing ratio and rotational Reynolds number will slightly reduce the inward film deflection. The local blowing ratios at hole exits are not evenly distributed along streamwise and spanwise direction under the combine effects of the three factors, which result in different film cooling performance at different streamwise locations and different blade heights.