串联式干气密封对超临界二氧化碳轴流透平气动性能的影响  

Effect of Series Dry Gas Seal on the Aerodynamic Performance of a Supercritical Carbon Dioxide Axial-inflow Turbine

作　　者：杜秋晚 张荻[1] 谢永慧[1] DU Qiuwan;ZHANG Di;XIE Yonghui(School of Energy and Power Engineering,Xi’an Jiaotong University,Xi’an 710049,Shaanxi Province,China)

机构地区：[1]西安交通大学能源与动力工程学院,陕西省西安市710049

出　　处：《中国电机工程学报》2021年第13期4576-4584,共9页Proceedings of the CSEE

基　　金：教育部高等学校学科创新引智计划项目(B16038)。

摘　　要：轴流透平叶顶不可避免地存在泄漏问题,严重影响了透平的运行效率与安全,工程上通常在叶顶布置密封结构来降低泄漏流的影响。为了进一步提升叶顶密封性能,该文基于一个1.5级超临界二氧化碳轴流透平,在动叶叶顶布置串联式干气密封,讨论了不同密封间隙下的流动特性和气动性能,并通过热流固耦合方法研究了密封端面变形特性,验证了其可行性。结果表明:串联式干气密封间隙为10mm时,无量纲相对泄漏量仅有2.43×10^(-5),透平效率相对于无泄漏结构仅降低了0.01%。随密封间隙增大,泄漏量增大,透平级内损失增大,效率降低。但在大密封间隙下,串联式干气密封结构相比于单级密封结构性能更突出。各个密封间隙下,密封端面内外径热力耦合轴向变形差均不超过27mm,且变形后透平可以维持较高效率。研究结果表明,超临界二氧化碳轴流透平叶顶布置串联式干气密封可以在保证安全性的前提下有效降低泄漏量,维持较高的气动性能。Leakage problem is inevitable in the tip of axial-inflow turbine, which seriously affects the efficiency and operating safety. In actual engineering, seal structure is usually arranged on the shroud to weaken the influence of leakage flow. In order to further improve the seal performance, a series dry gas seal was arranged on the rotor shroud of a 1.5-stage supercritical carbon dioxide axial-inflow turbine. The flow characteristics and aerodynamic performance under different seal clearance were discussed in detail. The feasibility of the series dry gas seal was verified by adopting the thermal-fluid-solid coupling approach to study the deformation characteristics of seal face. The results showed that the arrangement of series dry gas seal on the shroud can effectively reduce the leakage and improve the leakage characteristics. When the seal clearance was 10mm, the dimensionless relative leakage was only 2.43×10^(-5), and the efficiency was only 0.01% lower than that of turbine without leakage. As the seal clearance enlarges, the leakage and loss increased while the efficiency decreased. However, compared with the conventional single-stage dry gas seal, the series dry gas seal structure performed better under large seal clearance. Under all seal clearances, the thermo-mechanical axial deformation difference between the inner and outer radius of the seal face was less than 27mm, and high turbine efficiency can be kept after deformation. The results showed that arranging series dry gas seal on the shroud can effectively reduce leakage and maintain high aerodynamic performance with acceptable operating safety.

关 键 词：超临界二氧化碳 轴流透平 串联式干气密封 气动性能 损失 变形 

分 类 号：TM61[电气工程—电力系统及自动化]