EXPERIMENTAL BEHAVIOR OF A SHORT CYLINDRICAL SQUEEZE FILM DAMPER EXECUTING CIRCULAR CENTERED ORBITS

The experimentally determined behavior of a short radial squeeze-film damper with no end seals, executing circular centered orbits, is discu ssed. Accurate circular orbits were achieved, for epsilon values in th e range 0.1 and 0.8, by using digitally generated signals to drive two electromagnetic shakers. Radial and tangential dynamic fluid force co efficients were estimated from measurements of the applied forces and the orbit radii, using a simple algebraic method. Cavitation was found to occur when epsilon exceeded 0.5, at large orbit frequencies, and w as the cause of an observed jump-up phenomenon. The magnitude of an oi l stiffness effect, previously reported by the authors and confirmed b y the present results, was found to depend significantly on the oil su pply pressure. Its contribution to the total fluid force was of the sa me order as that from fluid inertia, in the case of small orbits (epsi lon much less than 1).