迷宫密封转子动特性三维CFD数值的研究

1引言旋转机械转子系统中的非接触密封在阻止流体泄漏的同时,还会产生重要的流体激振力,影响转子振动稳定性。与动压滑动轴承的油膜类似,密封中流体膜(汽膜、水膜或油膜)动力特性中的交叉刚度k是促使转子做非同步低频涡动的激振力来源,直接阻尼C可以生成对这种低频涡动的抑制力

A Study of Methods Used for Three-dimensional CFD (Computational Fluid Dynamics) Numerical Analysis of Dynamic Characteristics of Rotors with Labyrinth Seals

The aerodynamic force produced by fluid in labyrinth seals is a major factor that may lead to instability of a shaft system. This aerodynamic force can be described by a factor of seal dynamic characteristics. A vortex rotor-labyrinth seal three dimensional CFD (computational fluid dynamics) mathematical model was established. With a labyrinth seal at the inlet of a compressor serving as a specific case, the aerodynamic force at the rotor surface was calculated by using a general-purpose CFD software Fluent followed by a calculation of the seal dynamic characteristics factor. The calculated results when compared with those obtained by using another CFD software TASCflow and integrated-flow labyrinth seal calculation program DYNLAB indicate that the accuracy of loss-of-stability calculation under the three-dimensional CFD method is higher than that obtained by using the integrated-flow method. Finally, the impact of such factors as pre-swirling speed at the seal inlet, variation in clearances and cone-shaped axial clearance of seals etc. on seal stability was also calculated and analyzed in detail, thus providing a theoretical basis for decreasing steam flow excitations in seals.