Hydrodynamic performance of liquid film seals in circumferential beveled-step spiral grooves
(2.CNPC Dushanzi Petrochemical Company, Kelamayi, Xinjiang, China 833699)
【Abstract】To reduce liquid film pressure loss in liquid flow divergent zone between sealing surfaces and to improve sealing performance, the structure of circumferential beveled-step was introduced into rectangular section spiral groove and corresponding physical model was established. Based on the JFO cavitation model, the effects of bevel angle ratio on liquid film pressure distribution, cavitation occurrence, and liquid film hydrodynamic performance were studied at different groove depths. When bevel angle ratio was below 1/30, liquid film pressures of downstream and upstream pumping liquid film seals along circumferential and spiral line direction were enhanced rapidly but cavitation area ratio was dropped sharply, which was more significant for upstream pumping seals. With the increase of bevel angle ratio, leading edge pressure at liquid film rupture showed an increasing trend and trailing edge pressure at liquid film reformation showed opposite trend, but cavitation area ratio increased first and decreased later. The increase of groove depth contributed to the increase of liquid film pressure and the decrease of cavitation area ratio. When groove depth ranged from 8 to 12 μm and bevel angle ratio ranged from 0.1 to 0.3, the load-carrying capacities of both liquid film seals reached to peak values with about 13.5% maximum amplification for the former and about 28% for the latter, whereas increase of friction torque was smaller with about 4.6% maximum amplification. The leakage change along with the increase of bevel angle ratio was similar to the load-carrying capacity.
【Keywords】 spiral groove liquid film seals; circumferential beveled-step; hydrodynamic performance; liquid film pressure; cavitation area ratio; spiral groove liquid film seals; circumferential beveled-step; hydrodynamic performance; liquid film pressure; cavitation area ratio;
STORM T N, LUDWIG L P, ALLEN G P, et al. Spiral groove face seal concepts;comparison to conventional face seals in sealing liquid sodium (400 to 1000 Deg F) [J]. Journal of Lubrication Technology, 1968, 90 (2): 450–463. DOI:10.1115/1.3601580.
BUCK G S, VODEN D. Upstream pumping: a new concept in mechanical sealing technology[J]. Lubrication Engineering, 1990, 46 (4): 213–217.
SALANT R F, HOMILLER S J. Stiffness and leakage in spiral groove upstream pumping mechanical seals[J]. Tribology Transactions, 1993, 36 (1): 55–60. DOI:10.1080/10402009308983132.
WANG Y M, WANG J L, YANG H X, et al. Theoretical analyses and design guidelines of oil–film lubricated mechanical face seals with spiral grooves[J]. Tribology Transactions, 2004, 47 (4): 537–542. DOI:10.1080/05698190490500743.
HAO M M, LI Z T, REN B J, et al. Mechanical Seal Technology and Application[M]. 2nd ed. Beijing: China Petrochemical Press, 2014: 76–78 (in Chinese).
HAO M M. HU D M, GUO J. Performance study of the new upstream pumping mechanical seal[J]. Chemical Machinery, 2001, 28 (1): 12–15 (in Chinese).
BURTON R A. An experimental study of turbulent flow in a spiral–groove configuration[J]. Journal of Lubrication Technology, 1968, 90 (2): 443–449. DOI:10.1115/1. 3601579.
GAD A M, NEMAT-ALLA M M, KHALIL A A, et al. On the optimum groove geometry for herringbone grooved journal bearings[J]. Journal of Tribology, 2006, 128 (3): 585–593. DOI:10.1115/1.2197524.
WANG T, HUANG W F, WANG Y M. Research and progress of mechanical seals operating with vaporization transition[J]. CIESC Journal, 2012, 63 (11): 3375–3382 (in Chinese).
CHEN H L, WU Q B, ZUO M Z, et al. Overview on liquid film cavitation in mechanical seal faces[J]. Journal of Drainage and Irrigation Machinery Engineering, 2015, 33 (2): 138–144. DOI:10.3969/j.issn.1674-8530.14.0085 (in Chinese).
HAO M M, ZHUANG Y, ZHANG D H, et al. Numerical study on sealing performance of spiral groove liquid film seal considering effects of cavitation[J]. Journal of China University of Petroleum, 2015, 39 (3): 132–137. DOI:10.3969/j.issn.1673-5005.2015.03.018 (in Chinese).
QIU Y, KHONSARI M M. Experimental investigation of tribological performance of laser textured stainless steel rings[J]. Tribology International, 2011, 44 (5): 635–644. DOI:org/10.1016/j. triboint.2011.01.003.
XIE Y, LI Y J, SUO S F, et al. A mass-conservative average flow model based on finite element method for complex textured surfaces[J]. Sic. China-Phys. Mech. Astron., 2013, 56 (10): 1909–1919. DOI:10.1007/s11433-013-5217-z.
MENG X K, BAI S X, PENG X D. An efficient adaptive finite element method algorithm with mass conservation for analysis of liquid face seals[J]. Journal of Zhejiang University-SCIENCE (Applied Physics & Engineering) , 2014, 15 (3): 172–184. DOI:10.1631/jzus.A1300328.
ZHANG J Y, WANG X L. Performance of dynamically loaded journal bearing with couple stress fluids considering mass-conserving boundary condition[J]. Journal of Mechanical Engineering, 2010, 46 (15): 102–106. DOI:10.3901/JME.2010.15.102 (in Chinese).
YU T H, SADEGHI F. Groove effects on thrust washer lubrication[J]. Journal of Tribology, 2001, 123 (2): 295–304.
LIU D H, HU J B. Effect of cavitation model on the performance of radial grooved face seals[J]. Transactions of Beijing Institute of Technology, 2012, 32 (11): 1101–1104. DOI:10.15918/j.tbit1001-0645.2012.11.019 (in Chinese).
LI J H. Numerical computational method and experimental study for cavitation in mechanical seals[D]. Beijing: Tsinghua University, 2011 (in Chinese).
ZHAO Y M, HU J B, WEI C. Dynamic analysis of spiral-groove rotary seal ring for wet clutches[J]. Journal of Tribology, 2014, 136 (3): 031710-1-10. DOI:10.1115/1 4027548.
ZHAO Y M, HU J B, WU W, et al. Prediction of lubrication condition transition for spiral groove rotary seal rings[J]. Journal of Mechanical Engineering, 2013, 49 (9): 75–80. DOI:10.3901/JME.2013.09.075 (in Chinese).
LI Z T, HAO M M, YANG W J, et al. Effects of waviness and taper on cavitation characteristic of liquid lubricated mechanical seals[J]. CIESC Journal, 2016, 67 (5): 2005–2014 (in Chinese).
LI Z T, HAO M M, YANG W J, et al. Cavitation mechanism of spiral groove liquid film seals[J]. CIESC Journal, 2016, 67 (11): 4750–4761 (in Chinese).
NEMAT-ALLA M M, GAD A M, KHALIL A A, et al. Static and dynamic characteristics of oil lubricated beveled–step herringbone-grooved journal bearings[J]. Journal of Tribology, 2009, 131 (1): 011701–011707. DOI:10.1115/1.2908903.
ABDELAAI O A, KHALIL A A, NASR A M. Characteristics of oil-lubricated partially herringbone grooved journal bearing[J]. Journal of Engineering Sciences, Assiut University, 2009, 37 (4): 925–942.
JAMES D D, POTTER A F. Numerical analysis of the gas-lubricated spiralgroove thrust bearing-compressor[J]. Journal of Lubrication Technology, 1967, 89 (4): 439–443. DOI:10.1115/1.3617023.
KAWABATA N. A study on the numerical analysis of fluid film lubrication by the boundary-fitted coordinates system[J]. Transactions of Japan Society of Mechanical Engineers, Series C, 1987, 53 (494): 2155–2160.
CHRISTOPHE M, NOEI B, TOURNERIE B. A deterministic mixed lubrication model for mechanical seals[J]. Journal of Tribology, 2011, 133 (4): 042203. DOI:10.1115/1.4005068.
JAKOBSSON B, FLOBERG L. The finite journal bearing, considering vaporization[J]. Wear, 1958, 2 (2): 85–88.
OLSSON K O. Cavitation in dynamically loaded bearings[J]. Wear, 1967, 55 (2): 295–304.
ELROD H G. A cavitation algorithm[J]. Journal of Lubrication Technology, 1981, 103 (3): 350–354. DOI:10.1115/1.3251669.
PAYVAR P, SALANT R F. A computational method for cavitation in a wavy mechanical seal[J]. Journal of Tribology, 1992, 114 (1): 199–204. DOI:10.1115/1.2920861.
SHYY W, TONG S S, CORREA S M. Numerical recirculating flow calculation using a body-fitted coordinate system[J]. Numerical Heat Transfer, 1985, 8: 99–113. DOI:10.1080/01495728508961844.
PATANKAR S V. Numerical Heat Transfer and Fluid Flow[M]. London: Taylor & Francis, 1980: 72–73.
FESANGHARY M, KHONSARI M M. A modification of the switch function in the Elrod cavitation algorithm[J]. Journal of Tribology, 2011, 133 (2): 024501. DOI:10.1115/1.4003484.
XU S L, FAN W X. Multi-grid method for solving Reynolds equation[J]. Mechanical Engineering & Automation, 2013, (2): 70–71 (in Chinese).
LEBECK A O. Principles and Design of Mechanical Face Seals[M]. New York: John Wiley & Sons Inc. , 1991: 152–162.