Solutions for the combined motion of finite length squeeze film dampers around the bearing center

Analytical expressions for the hydrodynamic forces, and four related dynamic coefficients, are presented for finite length squeeze film dampers (SFDs) executing combined radial and tangential motion around the bearing center, with small amplitude. Previous analyses by Mulcahy (1980) and San Andres and Vance (1987) are shown to be particular cases of the present treatment. The influence of combined motion on the coefficients is found to differ in several respects, from that which can be deduced from results for one dimensional radial motion and circular centred orbital motion. The effects of combined motion on the mean pow velocity and the wall stress are also studied. The study provides further insight into the validity of bulk flow assumptions, often used when dealing with lubrication problems where fluid inertia effects are significant.