Theoretical and experimental study on the static stability of labyrinth seals

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Journal of Vibration and Shock ›› 2019, Vol. 38 ›› Issue (20) : 140-147.

MA Kai1 ZHANG Wanfu1 ZHANG Yao1 GU Qianlei1 CHEN Luqi1 LI Chun1 YANG Jiangang2

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Abstract

The static stability of labyrinth seals directly affects the safe and stable operation of a rotor system.This paper proposed an experimental method to identify the fluid-induced force and static stiffness coefficients.A three-dimensional fluid model of the labyrinth seals was established.And the static characteristics under different eccentricities and inlet pressure were studied.Theoretical results show a good agreement with the experiment results.The labyrinth seal with different eccentricities produces a fluid-induced force and a negative direct stiffness, which causes the rotor deviating from the geometric center of the stator.Both the fluid-induced force and negative direct stiffness increase with eccentricity and inlet pressure.The static instability is mainly due to the fact that the fluid velocity in the small clearance increases more rapidly along the seal leakage path.The mass inertial force is increased significantly and the pressure decreases.This results in greater pressure distribution in the larger clearance.The fluid-induced force and negative stiffness that tend to push the rotor away from the stator center are produced, and eventually lead to the static instability of labyrinth seals.

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MA Kai1 ZHANG Wanfu1 ZHANG Yao1 GU Qianlei1 CHEN Luqi1 LI Chun1 YANG Jiangang2. Theoretical and experimental study on the static stability of labyrinth seals[J]. Journal of Vibration and Shock, 2019, 38(20): 140-147

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