摘要：
To evaluate the influence of rotating annular seal with eccentric rotor on the operation efficiency and stability of turbomachinery,a novel 3D mesh generation method and a numerical approach were adopted to solve the static gas response forces and static stiffness coefficients for the rotating annular seal at high rotor eccentricity ratios based on the mesh deformation technique and steady RANS solutions.An investigation on the leakage and static destabilizing characteristics of rotating annular seal at high rotor eccentricity ratios was conducted.The leakage flow rate,static gas response (exciting) forces,static stiffness coefficients and flow field characteristics of a fully-partitioned pocket damper seal (FPDS) were computed at three pressure ratios (0.17,0.35,0.50),two inlet preswirl ratios (0,0.5) and seven eccentricity ratios (0.0,0.1,0.3,0.5,0.7,0.8,0.9).The results showed that the leakage flow rate increases with the eccentricity ratio.The rotor eccentricity and inlet preswirl result in a significant destabilizing cross-coupling stiffness,which may give rise to a risk of rotor whirling instability.The FPDS has a positive static direct stiffness as long as it operates at subsonic exit flow conditions,no matter the eccentricity ratio is high or low.For the choked exit condition,the FPDS shows negative static direct stiffness at low eccentricity ratios and then crosses over to positive value at the crossover eccentricity ratio 0.5,following a trend indicative of a parabola.The negative static direct stiffness may result in a full rotor eccentricity and rapid wear of seal due to rubbing contact.%为了评估转子发生偏心时非同心旋转密封对透平机械运行效率和安全稳定性的影响,提出了基于动网格技术和三维RANS方程的高偏心率旋转密封三维计算网格的生成方法,以及高偏心率旋转密封静态气流激振力和静态刚度系数的数值计算方法,研究了高偏心率下旋转密封的泄漏特性和静态动力特性.采用文中所提方法计算分析了3种压比(0.17,0.35,0.50)、2种进口预旋比(0,0.5)和7种偏心率(0.0,0.1,0.3,0.5,0.7,0.8,0.9)下的袋型阻尼密封泄漏量、静态气流激振力、静态刚度系数和流场特性.研究结果表明:旋转密封的泄漏量随偏心率的增大而增大;转子偏心和进口预旋产生了显著的正交叉刚度,易诱发转子发生偏心涡动而失稳;非阻塞工况下,旋转密封具有正的静态直接刚度;阻塞工况下,旋转密封的静态直接刚度存在穿越偏心率为0.5,静态直接刚度随偏心率的增大而增大,其值在穿越偏心率处由负值变为正值,以避免产生密封碰磨失效.
