新型非接触式自冲击密封结构设计与性能分析

Design and Performance Analysis of a New Non-contact Self-impact Seal

引入阻塞流体实施封严是非接触式密封的基本形式,节流效率低是制约此类技术性能提升、系统简化的关键。特斯拉阀凭借独特的造型结构,反向流动时形成的巧妙逐节冲击阻塞特性具有高效的节流效率。借鉴这一结构提出一种新型非接触式自冲击密封结构,兼具零磨损、高稳定性、结构简单和节流高效等特点,极具吸引力。应用CFD技术,仿真模拟不同结构和工况参数下新型密封的性能表现,结果表明:相比于水平型和阶梯型自冲击密封结构,层叠式结构具有更高的级数布置效率,并以AbBa式组合、交错比k=2时的抑漏效果最佳;新型密封对氢气、甲烷等低密度气体的泄漏偏高,对其他高密度气体的泄漏基本不变;新型密封泄漏量受压力影响较大、受转速影响较小,通过减小密封间距及增大密封级数可有效抑漏。相同工况下,以泄漏量为指标,新型密封较迷宫、螺旋、间隙密封可分别减漏27.79%、53.33%、64.34%;以密封间距为指标,新型密封实现标准泄漏时的密封间距是干气密封十几倍甚至几十倍,且新型密封间距为刚性间隙,稳定性更高。提出的新型密封结构,将衍生出一种密封新理论和原创技术,可以实现对现有非接触密封体系的理论拓展和技术革新。

Introducing blocking fluid to implement sealing function is a basic form of non-contact sealing.Low throttling efficiency is the key problem that restricts the performance improvement and system simplification of this kind of technology.By virtue of its unique shape structure,Tesla valve has high throttling efficiency and ingenious section by section impact blocking characteristic formed when reverse flow occurs.Based on this structure,a new type of non-contact self-impact sealing structure is proposed,which has the characteristics of zero wear,high stability,simple structure and high throttling efficiency.CFD technology is used to simulate the performance of the new seal under different structures and working parameters.Results show that:Compared with the horizontal and stepped self-impact sealing structures,the cascade structure has higher efficiency of series arrangement,and the best leakage suppression effect is achieved when the AbBa type combination and the staggered ratio k=2.The leakage of the new seal to hydrogen,methane and other low-density gas is higher,but the leakage of other high-density gas is basically unchanged.The leakage of the new seal is greatly affected by pressure and less affected by rotation speed,so the leakage can be effectively suppressed by reducing the sealing spacing and increasing the sealing series.Under the same working conditions,the new seal can reduce the leakage by 27.79%,53.33% and 64.34%,respectively,compared with labyrinth,spiral and clearance seals.The sealing spacing is taken as the indicator,the new seal to achieve standard leakage seal spacing is more than ten times or even dozens of times dry gas seal,and the new seal spacing is rigid gap,higher stability.The proposed new seal structure will derive a new mechanical seal theory and original technology,which can realize the theoretical expansion and technical innovation of the existing non-contact seal system.