Comparison of Air Ingestion vs. Dimensionless Parameters in Squeeze Film Dampers

Ingestion and entrainment of air into the Squeeze Film Dampers (SFDs) with open end result in a bubbly mixture that affects their damping capacity. The industrial applications demand dampers with low pressure supply and operating high speed, it means, it exists a necessity of propose a model to predict the air ingestion in this kind of bearing. Diaz and San Andre´s reported results of an extend research to quantify the effect bubbly mixture in the performance of the SFDs. They also advanced an analytic model for short infinity bearings (L/D = 0) which estimate the air ingestion as function of non-dimensional number named by them feed squeeze flow number. Me´ndez et al. advanced the understanding of the effect air entrainment. They propose a new dimensionless map to estimate the air volume fraction in finite length bearings. Although, their results are immediate applicability, they do not have been validated. The present work looks for confirm the results presented by Me´ndez et al. To achieve this, it is solved a compressible Reynold equation with a different numerical method. The results indicate that is necessary another dimensionless number to estimate the entrapment air and the dimensionless map proposed by Me´ndez et al. is valid only to bearings with an eccentricity-clearing ratio of 0.5248.