Fluid Inertia Effects on the Performance of Short and Long Squeeze Film Dampers Executing Periodic Vibration

A comprehensive study is made to examine effects of fluid inertia on pressure distribution, load capacity, wall shear stress differences (defined in Nomenclature), and velocity variation of flow in short and long Squeeze Film Dampers (SFDs). The SFD is assumed to execute a small excursion around an arbitrary static position. Exact solutions, in the form of a Fourier series, for fluid pressure and velocity are obtained for periodic motions of the SFD journal. An example of a horizontal motion, with various static positions in bearing clearance, is studied in detail for both short and long bearing configurations. It is found that the existence of fluid inertia generally increases the peak pressure value, and hence the load capacity. Wall shear stress differences and velocity distribution are also altered by the presence of the fluid inertia compared with inertialess flow, but the parabolic shape of the velocity may be maintained. Insight on how the fluid inertia effect is internally related to the viscous effects is also gained from this study.