冷却结构对中压透平级蒸汽冷却性能的影响

Effect of Cooling Structure on Steam Cooling Performance of Intermediate Pressure Turbine Stages

采用耦合流场计算和共轭传热的数值方法,研究了超超临界汽轮机中压缸前两级蒸汽冷却结构对动叶叶根和轮盘等部件冷却性能的影响,对比分析了原始结构和3种冷却孔结构中的中压缸前两级固体部件的温度分布。结果表明:4种冷却结构均可以对再热中压缸第一级动叶叶片、叶根、轮盘进行有效冷却;减小叶根底部冷却孔面积能够增大叶根和轮盘表面被冷却蒸汽覆盖区域的面积,提高冷却效果;封闭叶根底部冷却孔能够完全阻止主蒸汽入侵,达到叶根和轮盘固体域相对最佳的冷却效果;4种冷却结构均可保证第一级后部腔室下游蒸汽在较低的温度水平,从而实现对下游部件的进一步冷却。研究结果证明了,通过冷却孔的结构优化设计可以利用冷却蒸汽抑制高温主流蒸汽入侵轮盘腔室,有效提高超超临界汽轮机中压再热前两级的蒸汽冷却效果。

Effect of cooling structure on the steam cooling performance on the intermediate pressure turbine stages for ultra-supercritical steam turbine was numerically investigated by flow field calculation with conjugated heat transfer method.The computational domain includes the blade,blade root and wheel disc of the first two intermediate pressure turbine stages.The temperature fields and cooling effectiveness of the rotating components of the first two intermediate pressure turbine stages were compared between the original design and three different cooling hole designs.The results show that the four cooling structural designs are able to lower the temperature of the blade,blade root and wheel disc of the first stage.The reduction of the area of the cooling hole at the bottom of the blade root effectively increases the regions of the blade root and wheel disc covered by the cooling steam to improve the steam cooling effectiveness. The cooling structure with sealed cooling hole completely prevents high temperature main stream to ingress into the disc cavity.The optimum steam cooling effectiveness for the the blade root and wheel disc using this cooling hole structure is obtained.