| dc.description.abstract | In rotating machinery, squeeze film dampers (SFDs) reduce rotor synchronous response amplitude motions, provide structural isolation and enhance rotordynamic stability. Compared to conventional squirrel cage supported SFDs, integral squeeze film dampers (ISFDs) are more compact and require a shorter axial span. This paper presents predictions of pressure profile, lubricant flow rate, and dynamic force coefficients of a four-arc pads ISFD having a diameter D= 141 mm, length L= 0.4 D, and clearance c =0.004 D; and configured with distinct inlet orifices (d0 – 3 d0, d0=1.98 mm) and ends’ seal gaps (b1 - 3b1, b1 =0.191 mm = 1/3 c). The analysis quantifies the effect of the lubricant feedholes’ size and the end seals’ gap on the required flow and force coefficients of an ISFD for a typical compressor application. An increase in feed orifice diameter, from d0 to 2d0, rises significantly the fluid film pressure, delaying the onset whirl speed of oil cavitation although demanding of more flow rate. Incidentally, for a nominal gap b1 in the end plate seals, the ISFD damping and inertia coefficients reduce by almost 1/3 as the oil feed orifice diameter increases from d0 to 2d0. The damping and inertia coefficients of the ISFD are more sensitive to the end seal clearance than to the diameter of the oil feed orifice. In addition, predictions for the ISFD operating with an air in oil mixture shows that the damping and added inertia coefficients drop almost linearly as the inlet gas volume fraction (GVF) increases from 0.0 (all liquid) to 0.2. | |
