涡轮叶片内冷通道高性能肋流动与传热

Experimental Study of Flow and Heat Transfer of High-performance ribs for Internal Cooling of Gas Turbine Blades

涡轮叶片内部冷却通道内壁面布置扰流肋是一种高效的强化传热措施.本文在8500~60000雷诺数范围内,对直肋、斜肋、V肋和W肋开展实验研究,得到了四种肋的换热和流阻特性.实验结果表明:1)W肋具有最高的平均努塞尔数,是光滑通道充分发展流动传热性能的2.2~2.6倍,其次是V肋和直肋,而斜肋的传热性能最低,约是光滑通道的1.7倍;2)W肋表现出最大的流阻性能,是光滑通道的2.5~3.7倍,其次是V肋和直肋,而斜肋流阻最小,约为光滑通道的1.8~2.5倍。W肋具有最优的综合热性能,而直肋的综合热性能最低。另一方面,本研究还通过瞬态液晶热像技术获得了W肋表面详细局部传热分布,实验结果表明W肋中间的顶点迎风区域是强换热区,该区域与气流相互作用,热边界层较薄,有效强化了换热能力。

Rib turbulators are effective structures to enhance heat transfer in the internal cooling channel of gas turbine blades. The heat transfer and flow friction characteristics of different shaped ribs have been investigated in this paper. Experimental results show that the W-shaped rib has the highest average Nusselt number values, and the V-shaped rib and the straight rib have lower Nusselt number values, and the angled rib has the lowest values. When compared to the smooth channel, the channel with W ribs shows 2.2~2.6 times the Nusselt number values, and the channel with angled rib shows about 1.7 times Nusselt number values. It is also found that the angled rib shows the minimum friction factor values, which is about 1.8~2.5 times those of the smooth channel, and the W rib shows the friction factor values of 2.5~3.7 times those of the smooth channel. The W rib has the best overall thermal performance factor, and the straight rib shows the lowest overall thermal performance. On the other hand, the transient liquid crystal thermography technique has been used to obtain the local heat transfer performance on the surface with W ribs in the channel. Downstream the apex point of the W rib against the flow shows a high heat transfer enhancement region, where the oncoming flow strongly interacts with the ribs, producing downwashing vortex flow and making the boundary layer become thinner, which significantly enhances the heat transfer performance there.