柱面气膜密封动力特性系数的数值计算

Numerical Calculation of Dynamic Coefficients for Gas Film Cylinder Seal

针对柱面气膜密封系统动态特性分析问题,应用微扰线性化分布参数法建立密封气膜的微扰动态压力微分方程组,给出柱面气膜密封双自由度微扰下密封气膜的动态刚度和动态阻尼系数的计算方法;建立密封气膜的8个动态刚度、阻尼系数的有限元分析模型,给出有限元数值仿真计算流程和方法;通过算例验证数值计算模型和求解方法的正确性并重点研究可压缩数和平均膜厚对气膜动特性系数的影响。以柱面顺流螺旋槽带坝界面结构为例计算密封气膜各项动特性系数并给出不同条件下的变化规律曲线,气膜的正向刚度系数和正向阻尼系数呈现较为复杂变化状况,交叉刚度系数和交叉阻尼系数呈现轴对称特性。密封气膜动特性系数数值计算为稳定性分析提供了基础,为密封系统设计提供了指导。

Aiming at the dynamic analysis of gas film cylinder seal, the dynamic pressure differential equations of gas film are established by means of the linear perturbation method. A calculation method of dynamic stiffness and dynamic damping coefficients of a gas cylinder seal suffering small perturbations under two degrees of freedom is presented. The finite element analysis model of eight dynamic coefficients of gas film cylinder seal is established and the finite element numerical calculation process and method is presented. The model and the numerical method are proved to be correct through the computational example and a parametric study is performed to gauge the influence of the compressibility number and the average thickness of gas film to the dynamic coefficients. For downstream spiral-grooved gas film cylinder seal, the dynamic coefficients are obtained and the characteristic curves of the coefficients under different conditions are plotted. The direct stiffness and damping coefficients present a more complex variation, while the cross-coupled stiffness and damping coefficients are axisymmetric. The calculated results of the dynamic coefficients are helpful to the stability analysis of a gas cylinder seal and a guidance is provided for the design of the gas cylinder seal.