Comparison Between Plain and Herringbone-Grooved Aerodynamic Journal Bearings

Aerodynamic journal bearings are commonly used to support high-speed rotors. In applications where the shaft rotates concentric, like turbines and high-speed spindles, grooved aerodynamic bearings are used because they can run concentric. Plain aerodynamic journal bearings are unstable in the concentric position and are therefore not used for these applications. The instability is caused by the 90° attitude angle of the plain bearing at low rotational speeds. However by increasing the rotational speed the attitude angle of the plain bearing approaches the attitude angle of the grooved bearing. Moreover up to a certain speed the load capacity of the plain bearing is higher than the load capacity found for grooved bearings. In certain circumstances plain bearings might be preferable, since the plain bearing is much easier to manufacture. In this work a comparison is outlined for the plain and herringbone grooved bearings.