旋转状态下涡轮叶片复合冷却结构

Composite cooling structure on rotating turbine blade

采用三维流固耦合换热计算研究了旋转状态下涡轮叶片冷却结构的复合冷却性能,讨论了辐射换热和转速对综合冷却效果的影响.结果表明:结构1叶根处出现局部高温区,低冷却效率范围大,叶片整体温度分布不均匀,结构2通过更合理的气膜流量分配提高了前缘附近冷却效率,降低了叶片表面最高温度,结构3采用内部蛇形通道使吸力面冷却效率显著提高,叶片整体冷却效率分布较为均匀;考虑壁面辐射换热时叶片表面温度升高,当表面发射率为1时局部温升超过50K,壁面辐射换热的影响不能被忽略;压力面综合冷却效率随转速增大而升高,3种结构的局部冷却效率最高分别能提升15.6%,13.4%和16.4%,吸力面上除弦中区冷却效率随转速升高有所降低外,其余位置冷却效率变化不大.

Composite cooling performance of a rotating turbine blade cooling structure was investigated through heat transfer simulation with three-dimensional fluid-solid cou- pling, and the effects of radiation heat transfer and rotational speed on overall cooling effec- tiveness were discussed. Results showed that a local high-temperature area around the blade hub and hence a large scope of low cooling effectiveness occurred, leading to a nonuniform distribution of overall temperature for blade structure 1. The cooling effectiveness adjacent to the leading edge was improved, lessening the low effectiveness area as a result of more reasonable film flow distribution of blade structure 2. The cooling effectiveness on blade suc- tion side was markedly enhanced through internal serpentine passages and a uniform distribtion of integral cooling effectiveness was obtained for blade structure 3. The blade temperature increased with a regional temperature increment over 50 K for the surface emissivity of 1, while the effect of radiation heat transfer can＇t be ignored. The overall cooling effective ness on pressure side improved with the augmentation of rotational speed, resulting in a highest regional increase percentage of 15.6%, 13.4% and 16.4% for the three structures, respectively. Nevertheless, the cooling effectiveness on suction side produced little change excepl a reduction at mid chord region with the increase of rotational speed.