梳齿密封阻旋栅有效性的定量分析与判别

Quantitative Analysis and Evaluation on the Effectiveness of Swirl Brakes for Labyrinth Seals

阻旋栅是提高梳齿密封系统稳定性的重要部件,计算分析了阻旋栅-梳齿密封在不同阻旋栅间隙及预旋比下各密封腔室内压力、周向旋流强度及动力特性系数,对阻旋栅的有效性进行定量分析与判别。研究表明:阻旋栅间隙对各腔室内压力影响具有不同的趋势,随阻旋栅间隙减小,C腔室压力减小,而C-C腔室压力增大;提出了周向旋流增长率评价阻旋栅的影响范围,有阻旋栅密封周向旋流增长率沿泄漏方向降低,无阻旋栅密封基本保持不变。随着阻旋栅间隙的减小,阻旋栅对周向旋流的抑制范围增大;阻旋栅间隙的减小将增大C腔室内的交叉刚度,减小C-C内交叉刚度,密封整体有效阻尼提高,稳定性增强;预旋比的增加使得C-C腔室内交叉刚度增加,易引起系统失稳。

The swirl brake is an important component to enhance the stability of the labyrinth seal. This paper calculated the influence of the swirl brakes on the pressure distribution,circumferential swirling flow, and rotordynamic characteristics in each seal cavity. The effectiveness of the swirl brakes was quantitatively analyzed and evaluated. Results show that the influence of the swirl brake clearance on the pressure in each cavity has an opposite trend for Cand C—C. The pressure in Cdecreased with the decreasing swirl brake clearance, and the pressure in C—Cincreased with the decreasing swirl brake clearance. The growth rate of the circumferential swirling flow was introduced to evaluate the influence range of the swirl brakes. The circumferential swirling flow growth rate for labyrinth seal with swirl brakes decreased along the leakage direction, and that for the no-brake labyrinth seal remained was basically kept unchanged. As the clearance of the swirl brake decreased, the influence range of the swirl brake on the circumferential flow increased. The reduction of the swirl brake clearance increased the cross-coupled stiffness in Cand decreased the cross-coupled stiffness in C—C. The effective damping and the system stability could be improved. The increase of the preswirl ratio increased the cross-coupled stiffness in C—C, which is easy to cause the seal instability.