以S-CO2(supercritical carbon dioxide)为工质，采用计算流体力学(computational fluid dynamics，CFD)方法建立迷宫密封全三维数值分析模型，应用基于微元轨迹的密封动力特性系数理论识别方法获取密封动力特性系数,研究以S-CO2为工质的迷宫密封在不同密封腔室、间隙及齿数下的动力特性，并对比分析以空气为工质的密封系统稳定性。研究表明：密封直接复合刚度系数及平均直接阻尼系数频率依赖性较高，交叉复合刚度系数频率依赖性较低；密封有效阻尼系数在低频下（小于100 Hz）频率依赖性较强，〖JP2〗并随密封间隙的减小而略微增大；在高频下(100 Hz以上)，各腔室有效阻尼系数沿泄漏方向逐渐降低，且随齿数、密封间隙的增加而增大;10齿密封的有效阻尼系数约为4齿密封的128%~356%，0.16 mm间隙密封的有效阻尼系数约为0.32 mm间隙密封的80%~170%，与空气相比，以二氧化碳为工质的密封泄漏量较大，有效阻尼系数约为空气的167%~202%，系统稳定性增强。

In this paper,a threedimensional numerical model of the labyrinth seal with SCO2 (supercritical carbon dioxide) as working fluid was established using a computational fluid dynamics(CFD) method.The dynamic coefficient was obtained by using infinitesimal trajectory method.The dynamic characteristics of the labyrinth seal for different cavities,clearances and teeth quantities were studied and compared to those with air as the working fluid.Results show that the direct complex dynamic stiffness coefficient and average direct damping coefficient of the seal have high frequency dependence,while the crosscoupled complex dynamic stiffness coefficient has a low frequency dependence.The effective damping coefficient has strong frequency dependence at low whirling frequencies(less than 100 Hz) and increases slightly with the decreasing seal clearance.At high whirling frequencies (above 100 Hz),the effective damping coefficient for each cavity decreases gradually along the leakage direction,and increases with the increasing teeth number and sealing clearance.The effective damping coefficient of the seal with 10 teeth is about 128%~356% that of the seal with 4 teeth.The effective damping coefficient of 0.16 mm clearance is about 80%~170% that of 0.32 mm clearance.The leakage flowrate of the seal with carbon dioxide is higher than that with air.The effective damping coefficient of the seal with carbon dioxide is about 167%~202% that of the seal with the air,and the system stability with carbon dioxide shows better performance.

TK730.2

国家自然科学基金（51875361，51575105）；中国华能集团公司科学技术项目（HNKJ17-H34）