异侧多级旋流冷却结构对横流抑制及强化传热的影响

Effects of the Different-Side Multi-Stage Swirling Cooling Configuration onCrossFlow Suppression and Heat Transfer Enhancement

为进一步强化前缘旋流冷却,解决目前燃气透平叶片前缘多级旋流冷却结构相邻级之间流动折转带来的高压力损失问题,并提高叶片前缘传热均匀度,在已有研究基础上提出了一种新型的异侧多级旋流冷却结构。建立了原始同侧多级旋流冷却结构和新型异侧多级旋流冷却结构的模型,采用三维定常数值模拟分析方法,在保持靶面温度不变的条件下,对比分析了多个进口雷诺数条件下不同旋流冷却结构的流动与传热特性。仿真结果表明:冷却气体通过切向喷嘴射入旋流腔内部形成高速旋流,显著提高强化传热能力;对于单级旋流冷却,冷气的周向速度逐渐减小,轴向速度增大,横流逐渐形成,横流对下游射流产生冲击作用,削弱下游换热;多级旋流冷却结构对于旋流腔内部横流可起到横流抑制作用,周向平均努塞尔数有明显提高,但原始同侧多级旋流冷却结构相邻级之间的流动折转带来了很高的压力损失;异侧多级冷却结构在原有模型优点的基础上减少了22%的压力损失,改善了冷却气体分配的均匀度,实现了旋流冷却整体传热性能的进一步提升。

Based on previous studies,this paper proposes a novel multi-stage swirl cooling structure with different-side nozzles to further enhance the leading-edge swirl cooling and heat transfer uniformity of gas turbine blades,and tackle high pressure loss caused by flow deflection between adjacent stages of the multi-stage swirl cooling structure at the leading edge.The models of the original multi-stage swirl cooling structure on the same side and the new multi-stage swirl cooling structure on the different side are established;the flow and heat transfer characteristics of these two swirl cooling structures at multiple inlet Reynolds numbers are analyzed and compared with the three-dimensional steady numerical simulation method under constant target surface temperature.The calculation results show that the coolant is injected into the swirl chamber through tangential nozzles to form high-speed swirl flow,which significantly improves the heat transfer capacity.For single-stage swirl cooling,the circumferential velocity of coolant gradually decreases while the axial velocity increases,leading to the gradual formation of a cross flow.The cross flow impacts the downstream jet flow and weakens the downstream heat transfer.The multi-stage swirl cooling structure can inhibit the cross flow,and the average circumferential Nusselt number is increased obviously.However,the flow deflection between the adjacent stages of the original multi-stage swirl cooling structure on the same side brings high pressure loss.With the advantages of the original model,the multi-stage cooling structure on the different side reduces the pressure loss by 22%,improves the uniformity of coolant distribution,and further enhances the overall heat transfer performance of the swirl cooling structure.