Aerodynamic journal bearing with a flexible, damped support operating at 7.2 million DN

Abstract

This paper reports on the design, development and experimental validation of an aerodynamic journal bearing with a flexible, damped support operating at speeds up to 1.2 million rpm (= 7.2 million DN). In terms of the DN-number, this achievement represents to our knowledge a record for an air bearing of the self-acting type. Stabilization by means of a flexible, damped support therefore proves to be a promising solution to the dynamic stability problem of high-speed gas bearings. In order to select the support parameters in an optimal way, a stability study is performed leading to the formulation of a series of dimensionless design guidelines. The proposed implementation, which makes use of elastomeric O-rings in combination with a tunable squeeze-film damper, is discussed in detail. A method for the manufacturing of miniature bearing bushes with a wave-shaped film height profile is outlined. Experiments up to 683 280 rpm are performed with an air-driven turbine and up to 1203 000 rpm with a helium-driven turbine. Deceleration experiments are conducted in order to obtain an estimation of the frictional losses of the system.