Effect of mass flow ratios on the conjugate heat transfer of a metal turbine vane at medium temperature

To investigate the effect of mass flow ratios on the conjugate heat transfer of an air-cooled turbine vane, the surface static pressure test experiments and heat transfer experiments at medium-temperature (407.3 K) and medium-pressure (98.49 kPa) were conducted. An infrared thermal imager was used in the experiments to measure the temperature distribution of the test vane's outside surface. The effects of MFR (mass flow ratio), and mainstream Reynolds number were investigated. The experimental results show that the vane surface temperature is affected by both internal and external cooling. When the MFR was relatively small (MFR=1.0%, 2.0%, 3.0%), the integrated cooling effectiveness on the pressure surface gradually decreased along the coolant passage. At the same MFR, due to the different flow states on the vane surface, the integrated cooling effectiveness corresponding to the maximum mainstream inlet Reynolds number (2.64 × 10⁵) was the smallest, and the cooling effect deteriorated most noticeably at the leading edge. The cooling effect deterioration at the leading edge occurred when the MFR was lower than 4.0%. In addition, the growth rate of integrated cooling effectiveness prior to MFR=4% was significantly higher than that after 4.0%. When the MFR increased from 1.0% to 4.0%, the integrated cooling effectiveness increased by 89.8% with a faster growth rate, whereas it only increased by 14.9% when the MFR increased from 4.0% to 7.0%. An empirical correlation of the spanwise-averaged cooling effectiveness was also obtained. The mean relative error of the pressure surface was 7.64%, and that for suction surface was 3.27%.