三种不同端面几何形貌机械密封的性能试验研究
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摘要
为了改善机械密封的密封性能和端面摩擦副的润滑状况,人们将表面造型技术应用于机械密封以实现机械密封的零泄漏和非接触式运转。目前研究最广最深的是上游泵送机械密封和端面凹腔结构的动压型机械密封,但这两种机械密封也有一定的缺陷：泵送槽机械密封动压力不大；凹腔机械密封在泄漏问题没有得到解决,并且在较大的端面比荷情况下磨损严重。为解决这两个问题,本课题组提出了槽腔结合造型的机械密封以同时实现零泄漏和非接触,并从理论和试验两个方面进行了研究。
一、理论方面。
基于流体动压润滑理论分别建立了端面泵送槽形貌和端面凹腔形貌的机械密封流体动压润滑的数学模型,介绍了求解此数学模型的数值解方法。选择研究人员此前对槽和腔研究得出的最优参数,应用CFD软件Fluent,分别对端面螺旋槽造型机械密封环、端面凹腔机械密封环和槽腔结合机械密封环的进行了数值模拟。
1、对螺旋槽密封环的模拟显示：泵送槽区存在一定的动压力；整体液体压力分布在槽尾翼处较大,因此在一定的工况范围内能地域抵御介质压力。
2、对凹腔密封环的模拟显示：凹腔上方及其周边能产生流体动压力；凹腔底部压力最低,最容易产生空化效应。
3、对槽腔结合密封环的模拟显示：槽腔结合造型环的端面动压力分布较之单一螺旋槽造型环的端面动压力分布更均匀,有利于密封环运行的稳定性；槽腔结合环的端面整体动压力要比纯槽端面动压力大。
二、试验方面。
分别对端面凹腔机械密封环、槽腔结合机械密封环和未造型机械密封环进行了密封性能和摩擦性能的试验。对试验结果进行分析是得出以下结论：
1、两种造型的机械密封与未造型机械密封相比,具有明显优越的密封性能和摩擦性能。具体表现为：凹腔机械密封在一定工况范围内无泄漏,且具有相对于未造型良好的摩擦性能；槽腔结合机械密封在12种工况中均无泄漏,其摩擦系数远小于未造型的。
2、凹腔机械密封也存在一些缺点：在介质压力较小工况下试验时存在泄漏；在介质压力大而转速小时摩擦扭矩较大。而槽腔结合机械密封不存在该缺点。
分析表明：泵送槽的泵送效应提高了密封环的密封性能、还具有一定的动压效应；凹腔的动压效应改善了密封环的摩擦性能,这与理论研究的结果相一致。槽腔结合密封环的槽除泵送效应外,还能容纳液体,具有润滑作用,为凹腔的动压效应的产生提供了物质基础,泵送槽和凹腔耦合的效果远远大于两者各自效果之和。凹腔环在端面载荷较大转速小和密封环存在振动的情况下静环微凸体与动环的凹腔壁形成剪切与碰撞,将增大摩擦。
In order to improve sealing performance and the mechanical seal face friction pair lubricated conditions. People put surface modeling technology for mechanical seal mechanical seal to achieve zero-leakage and non-contact operation. The most widely researched ones are upstream pumping mechanical seal and seal with micro pores. However the two mechanical seals also have some shortcomings:Dynamic pressure of pumping groove mechanical seal is not strong. And leakage problem of cavity seal has not been solved; besides, serious wear and tear may generate under larger pressure condition. To solve these two problems, seal with micro pores and pumping grooves together on the ring face was developed to simultaneously achieve zero-leakage and non-contact. Study about it both on theory research and behavior test is under taken.
Mathematical models of groove modeling and pore modeling were established based on hydrodynamic lubrication theory. Numerical solution method is introduced to solve this mathematical model. Refer to the optimized design results of parameters about groove and pore. Numerical simulations on groove modeling, pore modeling and groove-pore modeling were carried out separately by CFD software which named Fluent.
Firstly, it is shown form the simulation result of upstream groove ring that a certain hydrodynamic pressure exists in groove area. And the distribution of the whole fluid pressure is more concentrated in the end of the groove which suggests the ability of keeping leakage out.
Secondly, it is shown form the simulation result of pore ring that hydrodynamic pressure exists over and around the pore. And the distribution pressure at the bottom of pore is low which implies the risk of capitation effect.
Thirdly, It is shown form the simulation result of groove-pore ring that the distribution of groove-pore ring is more equally than pure groove one.
Behavior test was carried out so that advantages and shortages of every face modeling could be compared. Two typical types of laser surface texturing seals-seal with micro pores and seal with micro pores and pumping grooves together on the ring face were tested on seal ability and frictional behavior, contrasting with non-texturing seal. Conclusion could be drawn according to the result of the test as follows.
On the one hand, it is shown that, the two types of texturing seals have excellent sealing and lubricating property. Specifically, seal with micro pores has comparatively better sealing and lubricating property than the non-texturing one in some conditions. And the seal with micro pores and macro pumping grooves performed better property in all test conditions.
On the other hand, however, the micro-pores texturing type has some shortcomings. It leaked a lot in low-load condition while showed considerable friction in high-load and low rotates speed conditions. The shortcomings didn't occur during the test on seal with micro pores and macro pumping grooves.
Detail reasons could be found after analysis:Firstly, the sealing behavior is improved because of the upstream effect. And it is reasonable that the dynamic effect of pores the can help to improve friction behavior. Both of which are belong to the conclusion of theory research. Secondly, besides pumping effect, the grooves of seal with pores and pumping grooves can hold liquid. When the liquid goes into interfaces.The faces were lubricated and the axial vibration was absorbed. Thirdly, friction coefficient of seal with pores may increase under high load and axial vibration conditions because of the cut and crash between pores and asperity peaks.
一、理论方面。
基于流体动压润滑理论分别建立了端面泵送槽形貌和端面凹腔形貌的机械密封流体动压润滑的数学模型,介绍了求解此数学模型的数值解方法。选择研究人员此前对槽和腔研究得出的最优参数,应用CFD软件Fluent,分别对端面螺旋槽造型机械密封环、端面凹腔机械密封环和槽腔结合机械密封环的进行了数值模拟。
1、对螺旋槽密封环的模拟显示：泵送槽区存在一定的动压力；整体液体压力分布在槽尾翼处较大,因此在一定的工况范围内能地域抵御介质压力。
2、对凹腔密封环的模拟显示：凹腔上方及其周边能产生流体动压力；凹腔底部压力最低,最容易产生空化效应。
3、对槽腔结合密封环的模拟显示：槽腔结合造型环的端面动压力分布较之单一螺旋槽造型环的端面动压力分布更均匀,有利于密封环运行的稳定性；槽腔结合环的端面整体动压力要比纯槽端面动压力大。
二、试验方面。
分别对端面凹腔机械密封环、槽腔结合机械密封环和未造型机械密封环进行了密封性能和摩擦性能的试验。对试验结果进行分析是得出以下结论：
1、两种造型的机械密封与未造型机械密封相比,具有明显优越的密封性能和摩擦性能。具体表现为：凹腔机械密封在一定工况范围内无泄漏,且具有相对于未造型良好的摩擦性能；槽腔结合机械密封在12种工况中均无泄漏,其摩擦系数远小于未造型的。
2、凹腔机械密封也存在一些缺点：在介质压力较小工况下试验时存在泄漏；在介质压力大而转速小时摩擦扭矩较大。而槽腔结合机械密封不存在该缺点。
分析表明：泵送槽的泵送效应提高了密封环的密封性能、还具有一定的动压效应；凹腔的动压效应改善了密封环的摩擦性能,这与理论研究的结果相一致。槽腔结合密封环的槽除泵送效应外,还能容纳液体,具有润滑作用,为凹腔的动压效应的产生提供了物质基础,泵送槽和凹腔耦合的效果远远大于两者各自效果之和。凹腔环在端面载荷较大转速小和密封环存在振动的情况下静环微凸体与动环的凹腔壁形成剪切与碰撞,将增大摩擦。
In order to improve sealing performance and the mechanical seal face friction pair lubricated conditions. People put surface modeling technology for mechanical seal mechanical seal to achieve zero-leakage and non-contact operation. The most widely researched ones are upstream pumping mechanical seal and seal with micro pores. However the two mechanical seals also have some shortcomings:Dynamic pressure of pumping groove mechanical seal is not strong. And leakage problem of cavity seal has not been solved; besides, serious wear and tear may generate under larger pressure condition. To solve these two problems, seal with micro pores and pumping grooves together on the ring face was developed to simultaneously achieve zero-leakage and non-contact. Study about it both on theory research and behavior test is under taken.
Mathematical models of groove modeling and pore modeling were established based on hydrodynamic lubrication theory. Numerical solution method is introduced to solve this mathematical model. Refer to the optimized design results of parameters about groove and pore. Numerical simulations on groove modeling, pore modeling and groove-pore modeling were carried out separately by CFD software which named Fluent.
Firstly, it is shown form the simulation result of upstream groove ring that a certain hydrodynamic pressure exists in groove area. And the distribution of the whole fluid pressure is more concentrated in the end of the groove which suggests the ability of keeping leakage out.
Secondly, it is shown form the simulation result of pore ring that hydrodynamic pressure exists over and around the pore. And the distribution pressure at the bottom of pore is low which implies the risk of capitation effect.
Thirdly, It is shown form the simulation result of groove-pore ring that the distribution of groove-pore ring is more equally than pure groove one.
Behavior test was carried out so that advantages and shortages of every face modeling could be compared. Two typical types of laser surface texturing seals-seal with micro pores and seal with micro pores and pumping grooves together on the ring face were tested on seal ability and frictional behavior, contrasting with non-texturing seal. Conclusion could be drawn according to the result of the test as follows.
On the one hand, it is shown that, the two types of texturing seals have excellent sealing and lubricating property. Specifically, seal with micro pores has comparatively better sealing and lubricating property than the non-texturing one in some conditions. And the seal with micro pores and macro pumping grooves performed better property in all test conditions.
On the other hand, however, the micro-pores texturing type has some shortcomings. It leaked a lot in low-load condition while showed considerable friction in high-load and low rotates speed conditions. The shortcomings didn't occur during the test on seal with micro pores and macro pumping grooves.
Detail reasons could be found after analysis:Firstly, the sealing behavior is improved because of the upstream effect. And it is reasonable that the dynamic effect of pores the can help to improve friction behavior. Both of which are belong to the conclusion of theory research. Secondly, besides pumping effect, the grooves of seal with pores and pumping grooves can hold liquid. When the liquid goes into interfaces.The faces were lubricated and the axial vibration was absorbed. Thirdly, friction coefficient of seal with pores may increase under high load and axial vibration conditions because of the cut and crash between pores and asperity peaks.
引文
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[3]Seedy J. High Pressure Upstream Pumping Seal Combination. US4290611,1981:09-22
[4]Etsion I. Enhancing sealing and dynamic performance with partially porous mechanical face seals [J]. Tribology Transactions, Oct,1994,37(4):701-710
[5]LAI T. Development of Non-Contacting,Non-Leaking Spiral Grove Liquid Face Seals[J]. Lubrication Engineering,1994,50(8):625-631.
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[7]张珊.机械密封环端面流体动压槽的加工方法[J].流体机械,2000(3)：38-41
[8]虞钢,虞和济.激光智能加工工程[M].北京：冶金工业出版社,2002.
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[2]Mayer E. The hydrodynamic in Mechanical Seal. Proc. of 4~(th) Inter. Conf. on Fluid Sealing.1970.124-134
[3]Seedy J. High Pressure Upstream Pumping Seal Combination. US4290611,1981:09-22
[4]Etsion I. Enhancing sealing and dynamic performance with partially porous mechanical face seals [J]. Tribology Transactions, Oct,1994,37(4):701-710
[5]LAI T. Development of Non-Contacting,Non-Leaking Spiral Grove Liquid Face Seals[J]. Lubrication Engineering,1994,50(8):625-631.
[6]王玉明,王强,吕岩,等.高速透平压缩机用螺旋槽端面密封及其系统的研制[J].流体工程,1992,20(4)：1-6.
[7]张珊.机械密封环端面流体动压槽的加工方法[J].流体机械,2000(3)：38-41
[8]虞钢,虞和济.激光智能加工工程[M].北京：冶金工业出版社,2002.
[9]Cheng H.S.,Chow C.Y.,Wilcock D.F.,Behavior of Hydrostatic and hydrodynamic Noncontacting Face Seals[J],Jour. of Lubr. Tech.,1968,90(2),510-519
[10]Gardner J.F. Combined Hydrostatic and Hydrodynamic Principles Applied to Noncontacting Face Seals Proc. Of Fourth Inter[J].Conf. on Fluid Sealing,1970,351-360
[11]Smalley A.J. The Narrow Groove Theory of Spiral Groove Gas Bearings[J]. Development and Application of a Generalized Formulation for Numerical Solutions, ASME Jour, of Lubr. Tech.,1972,99,86-92
[12]Sneck H..J. McGovern J.F. Analytical Investigation of the Spiral Groove Face Seals[J].ASME Jour, of Lubr. Tech.,1973,499-510
[13]Gabriel R.P. Fundamentals of Spiral Groove Nonconctacting Face Seals[J]. Lubrication Engineering,1979,33,367-375
[14]Brad A Miller Itzhak Green. Numerical Formulation For the Dynamic Analysis of Spiral-Grooved Gas Face Seals [J]. Journal of Tribology,2001,123:395-403.
[15]Ronen A. and Etsion I. Friction-Reducing Surface-Texturing in Reciprocating Automotive Components [J]. Tribology Transactions,2001,44, (3):359-366.
[16]Varenberg M. and Etsion I. Different aspects of the role of wear debris in fretting wear[J]. Wear,2002,252:902-910.
[17]Volchok A, HalPerin G and Etsion I. The effect of surface regular micro topography on treating fatigue life [J].Wear 2002,253:509-515.
[18]Etsion I. and Halperin G. A laser surface textured hydrostatic mechanical seal[J].Sealing Technoloy,2003, March:6-10
[19]Brazier V.,Kligerman Y. and Etison.I. A laser surface textured parallel thrust bearing [J], Tribology Transactions,2003,46,3:397-403
[20]Kligerman Y., Shinkarenko A. and Etsion I. Improving tribological performance of piston rings by partial surface texturing [J]. AIMETA International Tribology Conference,2004, September:14-17
[21]Mcnickle and Etsion I. Near-contact laser surface textured dry gas seals[J].Transaction of the ASME.,2004,126:788-794
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