Protection of Labyrinth Seals From Flexural Vibration

Resonance has been identified in several designs of stationary seals which have experienced failures. A resonant condition of the stationary seal occurs when the velocity of the rotating seal is equal to the velocity of propagation of the wave in the stationary seal. Self-excited vibrations have also caused fatigue failures particularly where damping is very small. Analysis of the mechanics of self-excited vibrations discloses a stability criterion which correlates pressure drop through seal with natural flexural frequency weight, and length. In addition to providing damping, the location of support of seal is shown to be of basic importance in preventing self-excited vibration.