主流湍流度对涡轮导叶压力面扩张型气膜孔冷却特性的影响

To investigate the influence of mainstream turbulence intensity on the film cooling characteristics of diffused film cooling holes on turbine vane pressure side, an experiment was carried out in the high subsonic wind tunnel, and the film cooling effectiveness and heat transfer coefficient downstream of the film hole row were measured by thermocouples. The inlet Reynolds number of the cascade ranged from 3.0×10⁵ to 9.0×10⁵, and the exit Mach number was 0.8. Two rows of single-row diffused film holes were located at the relative arc lengths of 25% and 70% on the pressure side. The high and low turbulence intensities were 14.7% and 1.3%, respectively. The experimental results show that for the row A, with the increase of the blowing ratio, the film cooling effectiveness increases first and then decreases in low turbulence intensity condition, while increases monotonously in high turbulence intensity condition. For the same blowing ratio condition, increased mainstream turbulence intensity strengthens the mixing of mainstream and coolant and enhances the dissipation of coolant, thus decreases the film cooling effectiveness. For the row B, elevated mainstream turbulence intensity decreases film cooling effectiveness at small blowing ratios, however suppresses the lift-off of coolant at large blowing ratios and increases film cooling effectiveness. The increase of blowing ratio significantly strengthens the heat transfer downstream of the row A, however has less effect on the row B. The increase of the mainstream turbulence intensity obviously raises the heat transfer coefficient ratio downstream of the row A and B. Overall, elevated mainstream turbulence intensity deteriorates the film cooling performance of the row A and B.