基于CFD柱面气膜密封静态力学性能分析

Analysis on steady fluid dynamics of cylindrical gas seal by CFD

为了探索新型密封槽结构对柱面气膜密封性能的影响,通过建立无槽和T型槽气膜计算模型,利用CFD软件对2种结构气膜的静压力分布、流体速度分布、剪应力分布进行对比分析.结果表明:无槽浮动环在偏心旋转过程中由于流体动压效应,使得气膜压力沿周向存在较大压差,最小膜厚处为高压区,最大膜厚处为低压区;T型槽气膜在槽型部位和槽根处气膜压力较大,由于T型槽模型静压分布最大压强大于无槽模型;T型槽浮动环可产生流体动压效应,使得气膜表面沿周向分布与槽数相等的压力波峰;与无槽浮动环相比,T型槽浮动环产生的流体动压效应使得流体速度大于无槽时数值;无槽气膜最大剪应力在最小膜厚处,T型槽气膜最大剪应力在最小膜厚处和T型槽根部坝区,且T型槽气膜最大剪应力大于无槽气膜最大剪应力.

In order to explore the effect of groove structure on the sealing performance of a new type cylindrical gas seal,the static pressure distribution,fluid velocity distribution and gas shear stress distribution in the sealing film are analyzed and compared between two structures by using the CFD software. The two structures include ordinary flat and T-groove floating rings. The results demonstrate that a large film pressure variation is found in the circumferential direction in the ordinary flat floating ring seal,specially,the highest pressure is in the area with the minimum film thickness or vice versa because of the fluid hydrodynamic effect generated by the eccentric rotation of the ring. For the T-groove floating ring,a large film pressure is in the groove and its root,and the maximum pressure is higher than that in the ordinary floating ring film. Because every groove can produce a hydrodynamic effect,the film pressure exhibits several peaks in the circumferential direction,and the number ofpressure peaks is equal to the number of grooves. Compared with the ordinary floating ring,the fluid velocity in the T-groove floating ring film is larger than that in the ordinary flat ring film due to even strong hydrodynamic effect generated by the grooves. The maximum shear stress occurs in the range with the minimum film thickness in the ordinary flat ring film,in the T-groove ring film,however,the maximum shear stress is located at the minimum film thickness and in the dam area of groove root,and its value is larger than the former.