| Popis: |
The average film cooling effectiveness is numerically investigated under different conditions of Reynolds numbers and rotation speeds at the suction side of the turbine blade. Three locations of the injection holes row were checked from the blade leading edge at 10%, 31%, and 69% of the blade axial chord length. Coolant is injected from eleven cylindrical holes at rotational speeds ranged from 0 to 4600 rpm and blowing ratios ranged from 0.91 to 2. For the mainstream hot gases, the investigation is performed at five Reynolds numbers of 50,000, 87,300, 300,000, 500,000, and 700,000. The inlet temperature of the coolant is 650 K, while the hot gases inlet temperature is 1500 K for all the studied cases. Location 1 shows the optimum average film cooling effectiveness. Near the film holes, the enhancement in the average film cooling effectiveness of location 1 is by 22% than location 2 and 35% than location 3. For location 1, the effectiveness is enhanced by 57% as the blowing ratio increases from M=0.91 to M=2. For location 2, the effectiveness improves as the rotational speed increases from 0 rpm until it reaches the optimum value at 900 rpm. Also, it is perceived that as the Reynolds number increases, the effectiveness worsens because of the increase in the hot mainstream momentum. |
