超临界二氧化碳高低齿梳齿密封动力稳定性研究

建立超临界二氧化碳(supercritical carbon dioxide，SCO2)高低齿梳齿密封三维数值计算模型，应用基于微元理论的密封动特性识别方法，研究凸台宽度及密封间隙对超临界二氧化碳梳齿密封动静特性的影响，并与传统梳齿密封进行对比. 研究表明：高低齿梳齿密封的交叉复合刚度系数对有效阻尼系数影响较小，主阻尼对其占主要影响. 在低涡动频率下(<160 Hz)，传统梳齿密封动力稳定性较好；而涡动频率高于160 Hz时，高低齿梳齿密封的有效阻尼系数约为传统梳齿密封的105%~113%；且存在1个最佳凸台宽度使密封系统稳定性最好(本文最佳值为5.13 mm)；随着密封间隙的减小，有效阻尼系数的大小与频率依赖性分别增大、增强. 高低齿梳齿密封泄漏量较传统梳齿密封降低约45.5%；凸台宽度5.13 mm、密封间隙0.4 mm时较原始模型(b=4 mm、c2=0.5 mm)泄漏量分别降低约5%和19%，高低齿梳齿密封泄漏量随密封间隙的减小而降低.A three-dimensional numerical calculation model for the supercritical carbon dioxide (SCO₂) high-low tooth labyrinth seal was established. The sealing dynamic characteristics identification method based on micro-element theory was utilized to investigate the effects of land width and seal clearance on the static and dynamic characteristics of the SCO₂ high-low tooth labyrinth seal, with a comparative analysis against traditional labyrinth seals conducted. The results demonstrate that the cross-coupled stiffness coefficients of the high-low tooth labyrinth seal have a relatively small impact on the effective damping coefficient, while the dominant damping plays a leading role. At low whirl frequencies (<160 Hz), the traditional labyrinth seal exhibits better dynamic stability; when the whirl frequency exceeds 160 Hz, the effective damping coefficient of the high-low tooth labyrinth seal is approximately 105%–113% of that of the traditional labyrinth seal. Furthermore, there exists an optimal land width that yields the best stability of the seal system, with the optimal value in this study being 5.13 mm. As the seal clearance decreases, both the magnitude of the effective damping coefficient and its frequency dependence increase and intensify, respectively. The leakage rate of the high-low tooth labyrinth seal is reduced by approximately 45.5% compared to that of the traditional labyrinth seal. When the land width is 5.13 mm and the seal clearance is 0.4 mm, the leakage rates are reduced by approximately 5% and 19% respectively compared to the original model (b=4 mm, c₂=0.5 mm). The leakage rate of the high-low tooth labyrinth seal decreases as the seal clearance is reduced.