A Volume of Fluid Method for Air Ingestion in Squeeze Film Dampers

The present work introduces a numerical model for squeeze film dampers (SFDs) operating simultaneously with vapor cavitation and air ingestion. The pressure is given by the Reynolds equation. The vapor cavitation model used in this work is based on Rayleigh-Plesset equation and was previously presented. Air ingestion occurring in open-end SFDs is dealt with by using a volume of fluid computational fluid dynamics (CFD) method not previously employed in lubrication problems. The original volume of fluid (VOF) method proposed by Hirt and Nichols was adapted to capture and track the free boundary between air and liquid in a thin-film lubricant. Numerical results are compared with experimental data of Adiletta and Pietra showing the simultaneous influence of vapor cavitation and air ingestion in an open-end SFD. These two phenomena have typical pressure values and appear at different locations and with a different extent. The vapor threshold is located on the low-pressure zone and is the lowest pressure value in the SFD, usually close to absolute zero. The air ingestion is characterized by a zone of almost constant pressure, usually close to atmospheric pressure (or, more generally, equal to the outer, exit pressure) and located between the minimum and the maximum pressures in the SFD. The numerical model proposed in this article deals simultaneously with these two effects. A simplified version of the air ingestion model for standard SFD applications is also introduced.