A Semi-Analytical Solution to the Dynamic Tracking of Non-contacting Gas Face Seals

The gas film stiffness and damping coefficients for a non-contacting gas face seal are obtained from the unsteady nonlinear Reynolds equation using the perturbation method. The seal assembly is converted to an equivalent spring-damper-mass system. The stator tracking motion is treated as a forced vibration caused by the rotor motion due to its runout and misalignment. The seal steady-state dynamic responses are solved semianalytically. Results for a typical spiral groove gas face seal agree well with that from a full numerical simulation. Stability of the seal axial pulsating and conical whirl are examined using the frequency dependent dynamic force and moment coefficients.