University of Bath

Non-contacting gas lubricated mechanical face seals

We aim to understand the dynamic response of gas lubricated face seals and to redesign the seal to improve sealing performance.

The next generation of sealing technologies need to be more efficient. For improved seals, industry needs reduced leakage between environments experiencing large pressure differences. And to be able to do this while the seal operates under challenging and destabilising conditions.

Gas lubricated mechanical face seals significantly improve sealing performance in the rotating machinery used in aerospace, energy and automotive industries. Current mechanical face seal designs incorporate two discs. One is fixed to a rotating shaft and the other is mounted in a stationary housing, which are in continuous contact throughout operation. This reduces flow across the seal to zero and eliminates leakage. Yet, operating with continuous contact between the faces causes thermal wear and distortion. This finite lifespan of the contacting mechanical face seals leads to increased costs through component replacement and machine downtime.

Gas lubricated mechanical face seals have similar geometry but with a thin film between the faces. This gives them operational advantages over traditional seals, including reduced wear and friction losses. But, current non-contacting face seals are often described as unpredictable and unreliable. There are a high number of premature and unexpected failures due to poor maintenance of the thin film between the faces.

We need a full understanding of the dynamic seal response to improve predictions and reduce unexpected failure. This will allow us to identify the safest and best operating conditions. Also, redesigning the face seal has the potential to maintain clearance under destabilising operating conditions. This would lead to better seal efficiency and a reduction in premature failure. The reduced fuel consumption, decreased machine downtime and increased service life would all help to save costs.