刷式密封泄漏流动特性影响因素的研究

采用基于改进Darcian多孔介质模型的Reynolds-Av-eraged Navier-Stokes方程求解技术,用数值模拟的方法分析了在一定径向间隙条件下压比和刷丝束厚度对刷式密封泄漏流动特性的影响规律。根据发表的刷式密封泄漏量试验数据,确定了刷丝束多孔介质的渗透率系数。利用所确定的刷丝束多孔介质渗透率系数,分别计算了在一定径向间隙条件下7种压比和5种刷丝束厚度时某轴端刷式密封的泄漏量和泄漏流动形态。计算结果表明,压比和刷丝束厚度均影响刷式密封的泄漏量,在一定压比条件下,泄漏量随着刷丝束厚度的增加而减小;在一定刷丝束厚度条件下,泄漏量随着压比的增加而增加。因为刷式密封泄漏量与压比和刷丝束厚度近似成线性变化,所以压比和刷丝束厚度对刷式密封内泄漏流动形态的影响可以忽略。

A Study of the Influence of Brush-type Seals on Leaking Steam Flow Characteristics

By employing techniques for seeking a solution to Reynolds-Averaged Navier-Stokes equation based on an improved Darcian porous medium model, a numerical analysis and study has been conducted of the law governing the influence of pressure ratio and bristle pack thickness on the leaking steam flow characteristics of brush-type seals under the condition of a given radial clearance. Based on the test data published for leaking steam flow rates of brush type seals, determined was the permeability coefficient of the porous medium of the bristle pack. By using the permeability coefficient of the bristle-pack porous medium thus obtained, calculated respectively were the leaking steam flow rates and flow patterns of brush type seals at the ends of a shaft under the condition of 7 pressure ratios and 5 kinds of bristle pack thickness at a given radial clearance. The calculation results indicate that both the pressure ratio and bristle pack thickness can influence the leaking steam flow rate of a brush type seal. Under the condition of a given pressure ratio, the leaking steam flow rate will decrease with an increase of bristle pack thickness. At a given bristle pack thickness, the leaking steam flow rate will increase with an increase of pressure ratio. As the leaking steam flow rate of a brush type seal assumes approximately a linear variation relationship with the pressure ratio and bristle pack thickness, the impact of the latter two items on the leaking steam flow patterns in a brush type seal can be virtually neglected.