一种新型组合内部冷却的流动和换热特性研究
Investigation on the Flow and Heat Transfer Behavior of a New Composite Internal Cooling Model

为了研究不同冷却结构对叶片前缘冷却性能的影响,探究综合性能更为优越的冷却结构,建立了旋流冷却、冲击冷却和旋流与冲击冷却相结合的新型冷却模型,在相同的进气腔、喷嘴数及位置、旋流腔和气动条件下进行了数值研究,对旋流冷却、冲击冷却和新型冷却模型的综合换热性能进行了对比分析,并探究了不同雷诺数下组合冷却的换热性能、冷气分配和压降的变化规律。研究结果表明:旋流与冲击冷却相结合的冷却方式综合换热性能最佳,其综合换热系数相较于旋流冷却提高了0.2％,相较于冲击冷却提高了12.5％,其压力损失低于纯旋流冷却和纯冲击冷却;在旋流与冲击冷却相结合的冷却中,随着雷诺数的增加,努塞尔数得到显著提升。由于上游冲击冷却气与主流的相互碰撞,削弱了主流流速,加之上游顺时针涡旋向下游的发展,使得冷却腔室末端位置的换热性能得到增强。在旋流与冲击冷却相结合的冷却中,旋流冷却部分产生的涡旋对下游的影响较强,抵抗上游的横流能力较高,旋流冷却与冲击冷却的相互作用能够产生一个大尺度对涡和单涡旋;冷气分配不随雷诺数变化,流经冲击喷嘴的冷气较少。
Influences of different cooling models on blade cooling were investigated, including swirl cooling, impingement cooling and composite cooling, in order to seek for more superior cooling models. The thermal performance of these cooling models was numerically compared under the conditions of same inlet chamber, same number and location of jet nozzles, same swirl chamber and aerodynamic parameters. Moreover, for the new type of composite cooling model, the effects of Reynolds number on the heat transfer performance, the cooling air allocation and the pressure drop were studied. Results indicate that this composite cooling has the highest thermal performance coefficient, i.e., 0？？2％ and 12？？5％ higher than that of swirling cooling and impingement cooling, respectively. Its heat transfer performance is slightly lower than swirl cooling and its pressure drop is the lowest among the three cooling models. As the Reynolds number increases, the Nusselt number will significantly rise. At the swirl chamber tip, the heat transfer performance is enhanced because the upstream impingement cooling air impacts the mainstream and decreases the velocity of mainstream. In addition, the upstream clockwise vortex develops along the downstream direction and enhances the heat transfer performance at the swirling chamber tip. The vortices produced by swirl cooling have dramatic effects on the downstream flow structure and have strong resistance against upstream flow. The interaction between swirl cooling and impingement cooling can produce a large？？scale vortex pair and single vortex. The cooling air allocation remains stable under different Reynolds numbers. The proportion of cooling air flowing through the impingement jet nozzle is the lowest among all jet nozzles