离心式压缩机密封动态特性分析及稳定性评价

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The stability of a centrifugal compressor is the key point in compressor design.The circumferential non-uniform pressure distribution due to fluid flow in seal clearance causes rotor instability.Adopting a numerical simulation method to predict the dynamic characteristic of seals is helpful for strengthening understanding of sealing mechanism,realizing sealing structure optimization and improving the rotor stability and the design reliability.Here,a numerical simulation method was used and the parametric programs were developed to build models of annular seals and the software ANSYS was used to predict the dynamic characteristic of seals and sealing properties.The study results showed that hole-pattern seal and honeycomb seal can provide larger stiffness and damping,and have better sealing properties than labyrinth seal＇s.Furthermore,the different structural parameters of hole pattern seals were compared,the basic laws of dynamic parameters of damping seals were found.Last,a 9-stage compressor rotor was taken as an example,the effects of different types of seal on the rotor stability were compared.The results of CFD simulation predicted the dynamic properties of seals and the effect of their structural parameters on rotor dynamic characteristics,and guided design of more stable compressors.稳定性问题是离心压缩机在向高端化方向发展过程中遇到的主要瓶颈,密封间隙内流体周向流动导致的压力在圆周方向不均匀分布是导致失稳的主要原因。采用数值模拟的方法预测密封的动力特性系数,有助于加强对密封机理的理解,实现密封结构的优化进而提高转子的稳定性和设计的可靠性。使用数值模拟的方法,首先基于ANSYSAP-DL语言,开发了参数化程序来构建迷宫密封、孔式阻尼密封及蜂窝密封的几何模型,采用ANSYSCFX软件,计算并比较三种密封的刚度及阻尼等动力学特性参数,研究结果表明孔式阻尼密封及蜂窝密封相对于迷宫密封可以提供更大的刚度和阻尼、且具有较好的密封特性。在此基础上,以孔式阻尼密封为对象,研究比较了不同孔间距,不同孔径的孔式阻尼密封,找到影响阻尼密封动力学参数的基本规律。最后以一台九级合成气压缩机转子为例,比较不同密封对转子稳定性的影响。CFD计算的结果预测了密封的动力特性以及密封结构参数对转子动力学特性的影响,可以指导密封的设计和压缩机改造,综合考虑性能和制造成本,实现优化设计。