Analysis and experimental verification on the leakage of labyrinth seals under multiple factors
SUN Weiwei1, LIU Yue1, LI Yongjian2, JIANG Jie3
1. Mechanical Electrical Engineering School, Beijing Information Science & Technology University, Beijing 100192, China; 2. State Key Laboratory of Tribology in Advanced Equipment, Department of Mechanical Engineering, Tsinghua University, Beijing 100084, China; 3. Chengdu Drainage Co., Ltd., Material Equipment Center, Chengdu 610039, China
Abstract：[Objective] As the main form of shaft seal, labyrinth seals provide several advantages, such as simple structure, convenient disassembly and assembly, and the ability to withstand high pressure and other harsh working conditions. They are widely used in centrifugal compressors, aeroengines, expansion turbines, and other rotating machinery. The diversity of labyrinth seal structures and the complexity of real working conditions make its internal gas flow and heat transfer very complex. The current literature reveals several factors that affect the leakage of labyrinth seals; however, comprehensive studies on the leakage characteristics of the multifactor coupling effect have been scarce. To improve the sealing performance of the labyrinth seal and reach the development trend of modern rotating machinery, performing detailed research on the structure optimization of labyrinth seals from multiple angles is crucial. [Methods] In this study, the flow field of the labyrinth seal was simulated by FLUENT software, the influences of geometric parameters and tooth structure of the labyrinth seal on leakage were analyzed by computational fluid dynamics (CFD). The labyrinth seal experimental system was established, which could realize the labyrinth seal experimental conditions under a maximum speed of 10 000 r/min and a gas supply pressure of 0.6 MPa. [Results] The experimental results exhibited that in the operating parameters, the pressure difference had a significant impact on the leakage, while the speed basically had no impact on the leakage. Moreover, comparison of the experimental results with the mathematical model showed that the maximum error between the mathematical model and the experimental results was 3%. The orthogonal experiment results indicated that the geometric parameters of the four tooth profiles had different degrees of influence on the leakage. Thus, the seal clearance had a remarkable effect on the leakage, while the duty cycle, depth width ratio, and tooth pitch had little effect on the leakage. After analyzing the tooth shape parameters, it was found that in the tooth shape structure, the inclined teeth had smaller leakage and reducing the inclination angle between the front teeth and the rear teeth would be beneficial to reducing the leakage. Analysis of the number of sealing teeth revealed that increasing the number of teeth was conducive to reducing the leakage without increasing the axial length. Moreover, this phenomenon was more obvious with increasing pressure difference. Therefore, when the total pressure difference was a constant value, the impact of the increasing number of teeth on the leakage rate would not change significantly. [Conclusions] In this study, the CFD model of the labyrinth seal is established by FLUENT software, and the internal flow field distribution and leakage characteristics of the labyrinth seal are revealed. Two geometric mechanism parameter definitions, namely, duty cycle and depth width ratio, are proposed. The parameter definition can effectively eliminate the coupling effect between the parameters, such as tooth height and tooth thickness, and provide an important reference for parameter optimization design. A sealing experimental system that can realize the working conditions of high speed and large pressure difference is generated and can monitor the leakage in real time. Moreover, the impacts of the working condition parameters, geometric parameters, number of seal teeth, and structural parameters on the leakage of the labyrinth seal are studied by the CFD model. This study is of great importance for the structural design of labyrinth seals.
孙巍伟, 刘跃, 李永健, 蒋杰. 多因素下迷宫密封泄漏分析及实验验证[J]. 清华大学学报（自然科学版）, 2024, 64(8): 1414-1423.
SUN Weiwei, LIU Yue, LI Yongjian, JIANG Jie. Analysis and experimental verification on the leakage of labyrinth seals under multiple factors. Journal of Tsinghua University(Science and Technology), 2024, 64(8): 1414-1423.
[1] ASLAN-ZADA F E, MAMMADOV V A, DOHNAL F. Brush seals and labyrinth seals in gas turbine applications[J]. Proceedings of the Institution of Mechanical Engineers, Part A:Journal of Power and Energy, 2013, 227(2):216-230. [2] ALIZADEH M, NIKKHAHI B, FARAHANI A S, et al. Numerical study on the effect of geometrical parameters on the labyrinth-honeycomb seal performance[J]. Proceedings of the Institution of Mechanical Engineers, Part G:Journal of Aerospace Engineering, 2018, 232(2):362-373. [3] 汤赫男,李赫,王世杰.热固耦合形变对BOG压缩机迷宫密封间隙的影响[J].润滑与密封, 2018, 43(11):24-27, 35. TANG H N, LI H, WANG S J. Effect of thermal-solid interaction deformation on the sealing clearance of labyrinth of the BOG compressor[J]. Lubrication Engineering, 2018, 43(11):24-27, 35.(in Chinese) [4] KASZOWSKI P, DZIDA M, KRZY AS'G LAK P. Calculations of labyrinth seals with and without diagnostic extraction in fluid-flow machines[J]. Polish Maritime Research, 2013, 20(4):34-38. [5] SUBRAMANIAN S, SEKHAR A S, PRASAD B V S S S. Influence of combined radial location and growth on the leakage performance of a rotating labyrinth gas turbine seal[J]. Journal of Mechanical Science and Technology, 2015, 29(6):2535-2545. [6] 纪国剑,吉洪湖.直通篦齿封严结构压损规律和临界特性的研究[J].航空动力学报, 2008, 23(3):415-420. JI G J, JI H H. Numerical and experimental investigation of pressure loss and critical sealing characteristics of straight-through labyrinth seals[J]. Journal of Aerospace Power, 2008, 23(3):415-420.(in Chinese) [7] SURYANARAYANAN S, MORRISON G L. Effect of tooth height, tooth width and shaft diameter on carry-over coefficient of labyrinth seals[C]//ASME Turbo Expo 2009:Power for Land, Sea, and Air. American Society of Mechanical Engineers. Orlando, USA:ASME, 2009:1147-1152. [8] KIRK G, GAO R. Influence of preswirl on rotordynamic characteristics of labyrinth seals[J]. Tribology Transactions, 2012, 55(3):357-364. [9] EGLI A. The leakage of steam through labyrinth seals[J]. Journal of Fluids Engineering, 1935, 57(3):115-122. [10] 赵炬颖,陈义,祝天一,等.螺旋槽对自适应迷宫密封的影响研究[J].润滑与密封, 2022, 47(1):1-7. ZHAO J Y, CHEN Y, ZHU T Y, et al. Influence of spiral groove on the performance of adaptive labyrinth seal[J]. Lubrication Engineering, 2022, 47(1):1-7.(in Chinese) [11] JIANG J, YANG Y Y, LI Y J, et al. Theoretical and experimental investigation on maximum pressure loads of labyrinth seal's teeth[J]. Advances in Mechanical Engineering, 2018, 10(10):1687814018794348. [12] JIANG J, YANG Y Y, HUANG W F, et al. Numerical and experimental investigation on uniformity of pressure loads in labyrinth seal[J]. Advances in Mechanical Engineering, 2017, 9(9):1687814017728455. [13] TANG H N, WANG S J, ZHAO J. Effect of fluid-structure interaction on sealed flow field and leakage rate based on computational fluid dynamics[J]. Journal of Shanghai Jiaotong University (Science), 2015, 20(3):326-330. [14] 白禄,孙丹,赵欢,等.转/静子齿对迷宫密封泄漏特性与动力特性影响机制研究[J].润滑与密封, 2022, 47(3):40-48. BAI L, SUN D, ZHAO H, et al. Research on influence mechanism of rotor/stator teeth on leakage and dynamic characteristics of labyrinth seal[J]. Lubrication Engineering, 2022, 47(3):40-48.(in Chinese) [15] 董振,魏来,汤赫男,等.轴向迷宫密封性能的流固耦合分析[J].润滑与密封, 2022, 47(1):89-93. DONG Z, WEI L, TANG H N, et al. Fluid-structure interaction analysis on axial labyrinth seal[J]. Lubrication Engineering, 2022, 47(1):89-93.(in Chinese) [16] YANG S P, TAN B S, DENG X F. Numerical and experimental investigation of the sealing effect of a specific labyrinth seal structure[J]. Mathematical Problems in Engineering, 2019, 2019:9851314. [17] ASOK S P, SANKARANARAYANASAMY K, SUNDARARAJAN T, et al. Neural network and CFD-based optimisation of square cavity and curved cavity static labyrinth seals[J]. Tribology International, 2007, 40(7):1204-1216. [18] 丁学俊,杨彦磊,黄来,等.直通式迷宫密封内可压缩流场的CFD数值模拟[J].流体机械, 2008, 36(6):25-29. DING X J, YANG Y L, HUANG L, et al. Numerical simulation of compressible flow in straight through labyrinth seal by CFD[J]. Fluid Machinery, 2008, 36(6):25-29.(in Chinese) [19] 巴鹏,张雨薇,吕忠阳,等.影响迷宫密封因素的分析[J].压缩机技术, 2016(2):24-27, 30. BA P, ZHANG Y W, Lü Z Y, et al. Analysis of the factors affecting labyrinth seal leakage[J]. Compressor Technology, 2016(2):24-27, 30.(in Chinese) [20] WHALEN J K, ALVAREZ E, PALLISER L P. Thermoplastic labyrinth seals for centrifugal compressors[C]//Proceedings of the Thirty-Third Turbomachinery Symposium. Houston, USA:Texas A&M University, 2004:113-126.
2024, Vol. 64 
