Dynamic Response to Axial Oscillation and Rotating Seat Runout in Contacting Mechanical Face Seals

Abstract

Contacting mechanical face seals are ubiquitous in many industries, e.g., petrochemical seals, automotive water pump seals, and low pressure gas seals. Environmental awareness and new strict regulations may force an even wider use of contacting seals in limiting leakage of toxic fluids. Contacting operation is achieved when the closing force exceeds a presumed opening force. For prolonged seal life it is desired that the contacting force be as small as possible. On the other hand, the contacting force must be big enough to ensure face contact. To maintain contacting operation the shaft speed must be smaller than some critical value, known as the separation speed. The separation speed is affected by many dynamic parameters of the system, among which is Ike damping of the support. This damping is either inherent in the system, in the form of a secondary seal, or is introduced especially to limit, for example, metal bellows radial vibration. The analysis herein complements an earlier investigation which was limited to undamped seals only. The current analysis reveals that support damping has an adverse effect on the separation speed and wear. Hence, an undamped seal is preferable for a flexibly mounted stator contacting seal configuration.