Due to the high-speed vibration and the poor lubricity at low-viscosity, the performance of the mechanical face seal for the next-generation high-speed transient-startup cryogenic turbopump is significantly different from that of the conventional mechanical seal. Using water as the low-viscosity sealed fluid, the performance of the seal is tested, focusing on the gas-liquid two-phase flow. The mechanism of the induced thermal vibration may be ascribed to the transient change of the fluid compressibility within the limited space. The experimental results show that under high-speed water-lubricated condition, while the mechanical seal can maintain a good sealing performance, the pattern of the performance change is more complicated. The two-phase flow phenomena occur in both the transition processes of the seal from the contact to non-contact state and the stable running state,, and the low-frequency oscillations of the temperature and friction of the seal pairs are significant. The amplitude of temperature oscillation can reach 30 ℃. When the vaporized two-phase flow occurs, the error between the theoretical and experimental results even reaches 50%. With the increase of the close force, the two-phase flow phenomenon between the seal gaps appear more significantly. The oscillation of temperature and friction caused by phase transition can be attributed to a self-excited vibration of the mechanical face seal.
[1] ZHANG G Y, ZHAO W G. Design and experimental study on the controllable high-speed spiral groove face seals[J]. Tribology Letters, 2014, 53(2):497-509.
[2] ZHANG G Y, CHEN G Z, ZHAO W G, et al. An experimental test on a cryogenic high-speed hydrodynamic non-contact mechanical seal[J]. Tribology Letters, 2017, 65(3):80.
[3] 张国渊, 赵伟刚, 闫秀天, 等. 基于POD降阶模型的非接触端面密封动态监测原理及仿真[J]. 航空学报, 2012, 33(2):354-361. ZHANG G Y, ZHAO W G, YAN X T, et al. Principle and simulation for real-time monitoring of the non-contact face seal based on POD model[J]. Acta Aeronautica et Astronautica Sinica, 2012, 33(2):354-361(in Chinese).
[4] 张树强, 李双喜, 蔡纪宁, 等. 动静压混合式气体密封追随性及主动调控振动特性数值分析[J]. 航空学报, 2012, 33(7):1336-1346. ZHANG S Q, LI S X, CAI J N, et al. Numerical analysis for the tracking property and active regulation vibration characteristics of dynamic-hydrostatic hybrid gas seals[J]. Acta Aeronautica et Astronautica Sinica, 2012, 33(7):1336-1346(in Chinese).
[5] 张国渊, 陈国忠, 赵伟刚, 等. 高速低温动静结合型机械密封结构优化及运转试验[J]. 航空动力学报, 2018, 33(5):1093-1102. ZHANG G Y, CHEN G Z, ZHAO W G, et al. Parameters optimization and test on the cryogenic hydrodynamic me-chanical seal[J]. Journal of Areospace Power, 2018, 33(5):1093-1102(in Chinese).
[6] ZHANG G Y, ZHAO W G, TIAN Y X. Experimental study on the water lubrication of non-contacting face seals for turbopumps[J]. Industrial Lubrication and Tribology, 2014, 66(2):314-321.
[7] HUGHES W F, WINOWICH N S, BIRCHAK M J, et al. Phase-change in liquid face seals[J]. ASME Journal of Lubrication Technology, 1978, 100(1):74-80.
[8] HUGHES W F, CHAO N H. Phase-change in liquid face seals Ⅱ-isothermal and adiabatic bounds with real fluids[J]. ASME Journal of Lubrication Technology, 1980, 102(3):350-359.
[9] ETSION I, PASCOVICI M D, BURSTEIN L. The boiling interface in a misaligned two-phase mechanical seal[J]. Journal of Tribology-Transactions of the ASME, 1997, 119(2):265-271.
[10] ARAUZ G L, SAN ANDRES L. Analysis of two-phase flow in cryogenic damper seals-Part Ⅱ:Model validation and predictions[J]. Journal of Tribology-Transactions of the ASME, 1998, 120(2):228-233.
[11] ARAUZ G L, SAN ANDRES L. Analysis of two-phase flow in cryogenic damper seals-Part I:Theoretical model[J]. Journal of Tribology-Transactions of the ASME, 1998, 120(2):221-227.
[12] OIKE M, NOSAKA M, KIKUCHI M, et al. Two-phase flow in floating-ring seals for cryogenic turbopumps[J]. Tribology Transactions, 1999, 42(2):273-281.
[13] ZHANG G Y, YAN X T. Analysis of two phase flow in liquid oxygen hybrid journal bearings for rocket engine turbopumps[J]. Industrial Lubrication and Tribology, 2014, 66(1):31-37.
[14] WANG T, HUANG W F, LIU X F, et al. Experimental study of two-phase mechanical face seals with laser surface texturing[J]. Tribology International, 2014, 72:90-97.
[15] WANG T, HUANG W F, LIU Y, et al. A homogeneous phase change model for two-phase mechanical seals with three-dimensional face structures[J]. Journal of Tribology-Transactions of the ASME, 2014, 136(4):041708.
[16] PENG X D, XIE Y B, GU Y Q. Evaluation of mechanical face seals operating with hydrocarbon mixtures[J]. Tribology International, 2003, 36(3):199-204.
[17] PENG X D, XIE Y B, GU Y Q. Simpler method for volatile medium pump mechanical seals[J]. Proceedings of the Institution of Mechanical Engineers Part J-Journal of Engineering Tribology, 2006, 220(J7):643-647.
[18] 彭旭东, 谢友柏, 顾永泉. 机械密封端面温度的确定[J]. 化工机械, 1996, 23(6):25-28. PENG X D, XIE Y B, GU Y Q. Determination of the end face temperature of mechanical seal[J]. Chemical Machinery, 1996, 23(6):25-28(in Chinese).
[19] 方艳峰, 彭旭东, 孟祥铠, 等. 热冲击对流体静压型机械密封性能影响的研究[J]. 流体机械, 2010, 38(10):23-28. FANG Y F, PENG X D, MENG X K, et al. Seal performance analysis of hydrostatic mechanical seal during thermal shock[J]. Fluid Machinery, 2010, 38(10):23-28(in Chinese).
[20] KANEKO S, IKEDA T, SAITO T, et al. Experimental study on static and dynamic characteristics of liquid annular convergent-tapered damper seals with honeycomb roughness pattern[J]. Journal of Tribology-Transactions of the ASME, 2003, 125(3):592-599.
[21] WU D Z, JIANG X K, LI S Y, et al. A new transient CFD method for determining the dynamic coefficients of liquid annular seals[J]. Journal of Mechanical Science and Technology, 2016, 30(8):3477-3486.
[22] HUDELSON J C. Dynamic Instability of undamped bellows face seals in cryogenic liquid[J]. ASLE Transaction, 1966, 9(4):381-390.
[23] ZHANG G Y, ZHAO W G, YAN X T, et al. A theoretical and experimental study on characteristics of water-lubricated double spiral-grooved seals[J]. Tribology Transactions, 2011, 54(3):362-369.
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