蜂窝密封的水封特性

为研究蜂窝密封的水封泄漏及流动特性,以两平行平板间的蜂窝密封结构为研究对象,数值求解蜂窝密封间隙内流动控制方程和Vreman亚格子紊流模型.采用有限体积方法离散Navier-Stokes方程,扩散项采用二阶中心差分格式,对流项采用二阶迎风差分格式.通过数值求解,得到了不同蜂窝半径和深度下蜂窝结构和与之相对应的梳齿密封结构的水封泄漏流量,分析了蜂窝密封的水封特性和封严机理.计算结果表明:蜂窝结构比传统梳齿结构具有更好的密封性能,蜂窝半径为6 mm,深度为4 mm时泄漏量相对最小,密封效果最佳.同时还发现泄漏量随着进出口压强差的增大而增大,而受板速影响甚微.最后通过对蜂窝内部流动特性分析发现:流体从间隙进入蜂窝空腔后产生了很强的旋涡而耗散部分动能,这种作用对降压节流起到主要作用.

Investigation into leakage characteristics of honeycomb seals for water

A honeycomb seal installed between two parallel flat plates was used as an analytical model; the three dimensional flow in the seal was solved numerically according to the Navier-Stokes equations and Vreman subgrid stress model to investigate the leakage characteristics and sealing mechanism in honeycomb seals for water. The finite volume method was used to discretize the Navier-Stokes equations and the second order upwind scheme and the second order central scheme are applied to the convection and diffusion terms in the equations, respectively. The leakage flow rates through the ho neycomb with different sizes of cells were obtained by means of numerical computation and compared with those in a corresponding labyrinth seal; eventually, the leakage characteristics and sealing mechanism were discussed. The results show that the honeycomb seal has better sealing performance than the labyrinth seal, a honeycomb with cells of 6 mm radius and 4 mm depth achieves the lowest leakage flow rate, causing the best sealing effect. Also, the leakage flow rate increases approximately linearly with increasing pressure difference across the inlet and outlet of the seal; however, the leakage flow rate remains nearly constant when the plate moving speed varies. Through further exploring the flow pattern in the honeycomb seal, it was observed that strong vortices have been generated in the honeycomb cell and consume the kinetic energy of stream. Such a flow pattern is mainly responsible for pressure drop and throttling effect in the seal.