负错位密封静力与动力特性的数值研究

Numerical study on static and dynamic characteristics of negative dislocated seal

提出了一种抑制气流激振力的负错位密封结构,建立了基于瞬态流场CFD动网格技术的负错位密封静力与动力特性求解模型,分析了偏心率、错位率等因素对密封泄漏量、周向压力、气流力与动力特性系数及密封转子稳定性的影响.结果表明:密封的泄漏量随偏心率与错位率的增加而增大;密封间隙流体周向压力呈正弦规律分布;与传统圆形密封相比,负错位密封形成发散的楔形间隙,降低流体动压效应,降低周向压力差,减小密封的切向力;随着偏心率的增加,密封的直接与交叉刚度以及交叉阻尼的绝对值均增大,直接阻尼降低;与传统圆形密封结构相比,该型密封可有效降低密封的交叉刚度,增加主阻尼,提高等效刚度与等效阻尼,改善了密封的稳定性.

A kind of negative dislocated seal based on the dislocated bearing theory was presented to eliminate hydrodynamic effects and reduce air induced force. The static and dy- namic characteristics of negative dislocated seals based on computational fluid dynamic （CFD） moving-gird technology were put forward. The effects of the eccentricity ratio and dislocation ratio on the leakage, circumferential pressure distribution, air force, rotor dy- namic characteristics coefficients, and seal rotor stability were analyzed. Results show the seal leakage increases with the eccentricity ratio and dislocation ratio~ the seal gap fluid cir- cumferential pressure distribution satisfies the sine law. Compared with the traditional cylin- der seals, the negative dislocated seal has divergent wedge gap, and reduces the hydrody- namic pressure effects, circumferential pressure difference and seal tangential force. This is the main reason for the negative dislocated seal suppression of air force. With the increase of the eccentricity ratio, the seal absolute value of stiffness and the cross-coupled damping increase and the direct damping decreases. This seal can effectively reduce the cross-coupled stiffness and increase the direct damping coefficients, the effective stiffness and effective damping so that the seal stability improves.