ISSN   1004-0595

CN  62-1224/O4

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复杂工况下槽底超滑移设计对液膜密封性能的影响

Influence of Super-Slip Design at the Bottom of Spiral Groove on Performance of Liquid Film Seal under Complex Operating Conditions

  • 摘要: 针对液膜密封在介质压力波动、高温和高速等极端工况下易发生扰动而严重影响密封性能的问题,为寻找扰动有效抑制方法,采用数值方法对比考察了边界压力波动及考虑黏温效应时介质温度、压力和转速对槽底超滑移设计和传统无滑移条件下的液膜空化、承载能力、泄漏特性和端面温度的影响. 研究结果显示,在压力波动时,超滑条件下的空化体积分数α、液膜开启力Fo和泄漏率Q波动与压力波动曲线之间无相位差,即在扰动停止后能够即刻恢复稳定运行,而在无滑移条件下存在滞后现象. 在黏温效应影响下,一方面,对于2种滑移条件,FoQ达到稳定的时间与初始介质温度、初始介质压力和转速无关,而α达到稳定的时间随初始介质温度的升高而缩短,槽区平均温度T随之延长,且此二者与初始介质压力和转速也无关;另一方面,相较于无滑移条件,槽底超滑移设计可以明显缩短αFoQT达到稳定的时间,显著提升Fo、减小α和降低T (在高转速时还可以显著降低Q),同时使Q远小于标准允许值,且较低的初始介质温度或较高的转速均可以使性能改善效果进一步增强,而初始介质压力影响甚微. 本研究表明槽底超滑移设计可以有效应对复杂环境扰动对液膜密封性能的不良影响.

     

    Abstract: Under extreme working conditions such as fluctuating media pressure, high temperature, and high speed, the liquid film seal is disturbed, and its stability is extremely prone to deterioration, which seriously affects its sealing performance. Therefore, in order to find effective methods to suppress disturbances, this study used numerical methods to comparatively investigate the effects of the boundary pressure fluctuations, as well as the effects of media temperature, pressure and rotational speed with considering the viscosity-temperature effect, on liquid film cavitation, load-bearing capacity, leakage characteristics, and end face temperature under groove bottom super-slip design and traditional no-slip conditions. The research results showed that under fluctuating media pressure, there was no phase difference between the fluctuation curves of liquid film cavitation volume fraction, opening force, and leakage rate over time and the pressure fluctuation curve under the super-slip condition. That was, after the disturbance stopped, the liquid film seal could immediately resume stable operation. However, under the no-slip condition, there was a significant lag phenomenon in the fluctuation curves of the above three performance parameters compared to the pressure fluctuation curve. When considering the viscosity-temperature effect, on the one hand, for both slip conditions, the time for the opening force and leakage rate to reach stability was independent of the initial media temperature, initial media pressure and rotational speed. However, the time for the cavitation volume fraction to reach stability decreased with increasing initial media temperature, while the average temperature in the end face groove area increased accordingly. Additionally, the cavitation volume fraction and the average temperature in the groove area were also independent of the initial media pressure and rotational speed. On the other hand, compared to the no-slip condition, the groove bottom super-slip design could significantly reduce the time for the cavitation volume fraction, opening force, leakage rate and average temperature in the groove area to reach stability. It could also significantly increase the opening force, reduce the cavitation volume fraction, and lower the average temperature in the groove area (and could significantly reduce the leakage rate at high rotational speeds). At the same time, the leakage rate was far less than the standard allowable value. Lower initial media temperatures or higher rotational speeds could further enhance the improvement in sealing performance, while the initial media pressure had minimal impact. This study demonstrated that the groove bottom super-slip design could effectively enable the liquid film seal to cope with the adverse effects of complex environmental disturbances on sealing performance. The results provided valuable insights for the design and optimization of liquid film seals in extreme working conditions, and contributed to improve the reliability and durability of sealing systems in various industrial applications.

     

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