燃气透平尾缘开缝区冷却性能的非定常研究
Unsteady Investigations on Cooling Performance of a Gas Turbine Tailing Edge Cut？？Back

采用分离涡模拟(DES)非定常数值计算方法,对3种吹风比(M为0.5、0.8、1.1)、3种肋柱结构(双列长肋G1、针肋G2a、针肋G2b)条件下燃气透平尾缘开缝区域的冷却性能进行了数值研究,并将计算得到的肋柱下游绝热壁面的展向平均冷却效率与实验结果进行了对比。实验结果表明,与RANS(雷诺平均N？？S方程)方法相比,DES非定常求解能获得较为准确的绝热壁面冷却效率分布。在3种吹风比条件下,肋柱下游壁面的展向平均冷却效率沿流向方向先上升,在达到最大值后迅速下降。吹风比为0？？8时,在肋柱中间截面的下游,冷却气膜覆盖的轴向距离最远,但冷却效果好的区域(温度低于310 K)面积最小。对于3种肋柱结构,在肋柱下游后半段冷却效率都会出现较大的下降,且唇缘处都出现了周期性的涡流脱落,涡流结构与肋柱的几何结构密切相关。与双列长肋G1相比,针肋结构(G2a、G2b)下游的绝热壁面温度分布均匀,G2b针肋下游的绝热壁面上所覆盖的冷却气膜厚度和稳定性都优于其他2种结构。
The film cooling performance in a gas turbine trailing edge cut？？back region is numerically investigated by using the unsteady Detached？？Eddy？？Simulation (DES) method. The laterally？？averaged cooling effectiveness on the adiabatic wall at the downstream of ribs is predicted at three blowing ratios (M=0？？5,0？？8,1？？1) and three rib？？array configurations (double in？？line rib array G1, pin？？fin array G2a and pin？？fin array G2b), and numerical results are compared with measurement data. Results and a comparison with the steady RANS (Reynolds？？averaged Navier？？Stokes equations) show that, the unsteady DES method has a superior accuracy in predicting the film cooling effectiveness distributions on the adiabatic wall at the downstream of ribs. The laterally？？averaged cooling effectiveness on the wall at the downstream of ribs goes up along the streamwise direction and then goes down sharply after reaching the maximum value at three blowing ratios. When M=0？？8, the coolant coverage on the adiabatic wall along the axial direction reaches the farthest among three blowing ratio cases, and is occurred just at the downstream middle region of ribs. However, the area with better film cooling effectiveness (temperature below 310 K) is the smallest among the three blowing ratio cases. The film cooling effectiveness significantly decreases on the rear part of the adiabatic wall for three rib？？array configurations, and the periodical vortex shedding is appeared at the downstream of the blunt lip. It indicates that the vortex shedding structures are closely related to geometrical configuration of the rib？？array. The temperature distributions on the adiabatic wall downstream of ribs are much uniform for the pin？？fin ribs (G2a and G2b). Among three rib？？array configurations, G2b performs better than the other two designs in both the film cooling thickness and the stability in the trailing edge cut？？back region