大孔径端面机械密封性能的研究

发布时间：2018-06-05 18:54

本文选题：机械密封 + 动压效应　；参考：《浙江工业大学》2014年博士论文

【摘要】：以微孔为代表的表面织构技术在机械密封端面中得到广泛应用,然而其在高压和大膜厚条件下产生的动压效应较低,不能有效改善该工况下的密封性能,从而限制了其进一步的应用。针对此,提出了一类大孔径流体动压型表面织构,使润滑液膜产生汇聚和导向,以期显著提高其动压效应和液膜的稳定性。论文以大孔径流体动压型机械密封为研究对象,考虑液膜的空化现象,建立其理论模型,研究了密封操作参数与孔型尺寸对密封性能的影响情况,揭示大孔型表面织构的作用机理,对其孔型结构进行优化分析。考虑到密封介质压力对密封变形的影响和液膜压力与端面变形间的耦合作用,建立了大孔型机械密封的流固力耦合模型,结合有限单元法与有限差分法求解物理模型,研究了操作参数和结构参数对密封环变形和密封性能的影响情况。搭建了密封性能试验台架,进行了不同排布的大孔型表面织构的摩擦磨损试验和相应机械密封的密封性能试验。研究结果显示：(1)相较于微孔端面机械密封,大孔径端面密封在低速下更易产生空化效应,具有更强的动压开启特性；在较大的压力范围内变化,孔径或半轴长越长,端面间的液膜稳定性越好；(2)大菱形孔具有比其它型孔更好的液膜稳定性、开启特性及较小的泄漏率,在低速时双向倾斜大菱形孔端面密封可快速打开,可有效减少启动时的摩擦磨损和泄漏率,非倾斜大菱形孔的液膜稳定性是最好的；(3)密封端面的周向波度变形是由端面的孔型结构和转速所决定的,而端面的径向锥度变形是由密封环的宏观结构和内外压力差所决定,且两类参数对端面变形的作用是互不影响的；(4)试验显示：双向双列倾斜菱形孔、ζ=0.6～0.9和越大的孔径端面密封,可获得最低的摩擦系数、温升和磨损量,同时也验证了大孔径端面具有较好的动压效应和耐磨性能。论文成果完善了大孔径端面密封的设计理论与方法,解决了转速较低设备中微孔端面密封动压效应弱与较大压力范围内液膜稳定性差的问题,具有很强的实用价值。
[Abstract]:The surface texture technology, represented by micropores, is widely used in the mechanical seal face, but the dynamic pressure effect is low under the condition of high pressure and large film thickness, so it can not effectively improve the sealing performance under the condition of high pressure and large film thickness. This limits its further application. In order to improve the dynamic pressure effect and the stability of liquid film, a kind of surface texture with large pore diameter hydrodynamic pressure is proposed, which leads to the convergence and orientation of the lubricating liquid film. In this paper, the large aperture hydrodynamic pressure mechanical seal is taken as the research object. Considering the cavitation phenomenon of liquid film, the theoretical model is established, and the influence of sealing operation parameters and pass size on the seal performance is studied. The action mechanism of surface texture of macroporous surface was revealed and the pore structure was optimized and analyzed. Considering the effect of sealing medium pressure on seal deformation and the coupling effect between liquid film pressure and end surface deformation, a fluid solid coupling model of large pass mechanical seal is established, and the physical model is solved by combining finite element method and finite difference method. The effects of operation parameters and structural parameters on the deformation and sealing performance of seal ring were studied. A test bench for sealing performance was set up, friction and wear tests of large pass surface texture with different arrangement and sealing performance tests of corresponding mechanical seals were carried out. The results show that, compared with the mechanical seal with micropore end face, the large aperture end face seal is easier to produce cavitation effect at low speed, and has stronger dynamic pressure opening characteristics, and the longer the aperture or half shaft length is, the longer the aperture or half shaft length is when the pressure range is large. The better the stability of the liquid film between the end faces is, the better the liquid film stability, the opening characteristic and the smaller leakage rate of the big diamond hole are compared with the other holes. The seal of the bidirectional inclined big diamond hole can be quickly opened at low speed. It can effectively reduce the friction, wear and leakage rate during start-up. The liquid film stability of the non-inclined big diamond hole is the best. (3) the circumferential waviness deformation of the end face of the seal is determined by the pass structure and the rotational speed of the end face. However, the radial taper deformation of the end face is determined by the macro structure of the seal ring and the difference between the internal and external pressure, and the effect of the two kinds of parameters on the end face deformation is independent of each other. The test shows that the bidirectional double-row inclined rhombic hole, the Zeta _ 0. 6 ~ 0. 9 and the larger the aperture end face seal, The lowest friction coefficient, temperature rise and wear rate can be obtained. At the same time, it is proved that the large aperture end face has better dynamic pressure effect and wear resistance. In this paper, the design theory and method of large aperture end face seal are perfected, and the problem of weak dynamic pressure effect and poor stability of liquid film in large pressure range is solved in low rotating speed equipment, which is of great practical value.
【学位授予单位】：浙江工业大学
【学位级别】：博士
【学位授予年份】：2014
【分类号】：TH136

【参考文献】