涡轮叶片内部多通道微小扰流肋冷却流动传热实验研究

Study of Heat Transfer and Pressure Loss in Multi-pass Cooling Passages With Micro-Ribs for Turbine Blade

在涡轮叶片内冷多通道中布置微小扰流肋是一种高效的强化换热措施。本文开展了具有三个弯折通道的涡轮叶片内部冷却结构流动压力损失和传热实验,该冷却通道的单侧面和双侧面布置有W形微小肋。通过开展稳态流动传热实验,获得了雷诺数为8500~60000时的平均换热和沿程流阻特性.在单侧面肋化通道中,W肋在第一流程换热最差,而在第三流程换热最好;通道双侧面布置w肋时,通道内的换热能力都获得增强,三个流程分别比光滑通道提高了0.5~1.4倍、1.5~1.7倍和1.9~2.1倍,但流动阻力明显增大。通过开展瞬态液晶热像传热实验还表明,W微肋板表面在第二流程换热强度分布主要受气流转折作用的影响,气流因转折引起的剧烈掺混使湍动能更高,有效地强化了第二流程表面的对流换热能力。

Rib is an effective structure to enhance heat transfer in the cooling channel of turbine blades.Steady-state and TLC experimental work has been carried out with both the single and double ribbed-ducts for each pass respectively,while Reynolds number ranges from 8500 to 60000.According to the experimental results,the third pass exhibits the best thermal performance while the first Pass has the lowest area-averaged Nusselt numbers.The double ribbed-duct shows area-averaged Nusselt numbers of 1.4,1.7,and 2.1 times of the single ribbed-duct,but results in higher pressure losses by 50% to 80%.Transient liquid crystal technology has been used to obtain local surface heat transfer performance with W-ribs in the three-pass flow channel.It is found that the ribs are the key factor for enhancing heat transfer in the first pass,while the turning of the airflow is the main factor that affects the heat transfer in the second and third pass,an increase in turbulent kinetic energy and heat transfer enhancement has been reported.