Collocation Method for Finite Length Squeeze Film Dampers With Variable Clearance

The Collocation method is used to study the characteristics of a finite length Squeeze Film Damper (SFD) with variable clearance. The secant stiffness and damping coefficients of the SFD for centered circular orbits is compured by solving Reynolds equation for a finite bearing, using the collocation method. A significant disadvantage with a conventional SFD is the highly nonlinear variation of secant stiffness and damping coefficients with eccentricity ratio. It is shown in this paper that by suitably varying the parameters α and λ, which control the nature of clearance variation, the secant stiffness and damping coefficient variation with eccentricity; ratio can be altered to better suit specific design needs. Nonlinear transient analysis of a single journal in a finite SFD is carried out, and, periodic journal center orbits due to unbalance response for uncentered finite SFD’s are also obtained. The centered circular orbit response for different unbalance values and speeds is obtained. Results from the Collocation method show excellent agreement with finite difference results. The Collocation method is shown to be an efficient and viable technique that is an order of magnitude computationally faster than the finite difference method, for static and dynamic analysis of finite length SFD’s.