透平叶片双工质冷却流量和流向的优化配置

Investigation on Optimal Allocation of Mass Flow and Direction for Binary Cooling Turbine Test Blades

采用SST转捩模型求解了三维定常雷诺时均Navier-Stokes方程,对具有多个光滑内冷通道的试验叶片进行了气热耦合的数值计算,同时研究了蒸汽、空气冷却工质的流量大小和流向分配对叶片表面温度分布和冷却效率的影响.结果表明:SST转捩湍流模型能够较好地预测叶栅内的传热特性;增加冷却工质的流量,叶片温度明显降低且表面温度分布更加均匀,当冷却工质流量比从0.018 74提高到0.093 71时最大温差下降了约30K,叶片表面的平均冷却效率最大可提升17%,叶片达到最大冷却效果的冷却流量比的最佳值为0.074 97;改变叶片的第2、第4通道的冷却工质流向,可以改善叶片中弦区域沿展向的温度梯度,第5通道采用双向进气的配置方案可以很好地降低叶片尾缘区域的温度梯度,从而改善叶片整体温度的分布.

The three-dimensional viscous steady Reynolds-averaged Navier-Stokes equations and energy equation were adopted to solve coupled velocity and temperature fields for investigating the effects of the mass flow rate and the flow direction of cooling-steam and cooling-air on the blade surface temperature distribution and cooling efficiency on the basis of the SST transition turbulence model. The numerical results indicate that the simulation with the SST transition tur- bulence model can predict the heat transfer characteristics in the blade cascade. The blade surface temperature decreases significantly and its temperature distribution is more uniform with an in- crease in the mass flow rates of the coolants. Moreover, when the mass flow rate ratio is in- creased from 0. 018 74 to 0. 093 71, the maximum temperature difference fails by 30 K and the av- erage cooling efficiency of the blade surface rises by up to 17 ~. When the mass flow rate ratio is 0.074 97, the best cooling efficiency of the blade could be obtained in this study. In addition, changing the flow directions of the second and fourth channels can reduce the temperature gradi- ent and effectively improve the temperature distribution in the blade midchord region along span- wise, and adopting the double-inlet configuration in the trailing-edge region will lead to a lower temperature gradient and ameliorate the whole temperature distribution of the blade.