Experimental and theoretical analysis of a rigid rotor supported by air foil bearings

¹ Department of Mechanical Engineering, DTU-Technical University of Denmark, 2800 Kgs. Lyngby, Denmark
² Siemens A/S - Aeration Competence Center, 3000 Helsingør, Denmark

^a Corresponding author: jon@stadsen.dk

Received: 26 May 2014
Accepted: 8 July 2014

Abstract

The popularity of compressors utilizing foil bearings is increasing. Their mechanical design is challenging, and an accurate prediction of the bearing coefficients is important. A mathematical model taking into account the foil structure, and the detailed geometry of a three pad foil bearing are presented. The steady state solution and dynamic coefficients are obtained through zeroth and first order perturbed equations respectively. Analysis of the foil structure reveals the importance of distinguishing between a static foil stiffness for the zeroth order equation and a dynamic stiffness for the first order equation. Calculated bearing coefficients are compared to experimental results obtained from a dedicated test rig. Generally, good agreement is observed and minor discrepancies for the damping coefficients are discussed.