DYNAMIC RESPONSE OF A PIVOT-MOUNTED SQUEEZE FILM DAMPER: MEASUREMENTS AND PREDICTIONS

Squeeze film dampers (SFDs) are widely used to reduce vibration levels in rotating equipment. These devices are installed in series with bearings and are subjected to precessional motions with the inner and outer damper surfaces remaining parallel. Alternatively, this paper evaluates the dynamic performance of a damper describing angular motions. This paper includes the design and development of a test rig, and the experimental dynamic response of the pivot-mounted journal benchmarked with a predictive finite element code. The experimental setup uses a housing with two different radial clearances-3 mils (76.2 mu m) for the lower land and 12 mils (304.8 mu m) for the upper land-which is open to atmosphere. This work also includes developing a pivot-mounted SFD computer code, capable of predicting the dynamic performance of unpressurized 2 pi and segmented dampers. The numerical tool can predict the dynamic performance of a damper that has multiple land diameters with different clearances. The experimental results identify stiffness, damping, and added mass for both the SFD and its structure, showing a close correlation with the numerical calculations using three different fluid viscosities.