KU Leuven: Breakthrough in high-speed bearings

Research lead

The Department of Mechanical Engineering at KU Leuven has set a new speed record of 1.2 million rotations per minute (RPM) for making a shaft rotate. This is 133 times faster than the maximum RPM of a Ferrari 458 Italia.

The shaft in question is 6 mm in diameter, and is suspended in aerodynamic radial bearings, so that it floats on a thin layer of air that is only a few micrometres (1/1000th of a millimetre) thick. The shaft does not touch any other parts, meaning there is no wear, even at 1.2 million RPM.

At its fastest, the shaft surface reaches a speed of 377 metres per second, or Mach 1.1 (1.1 times faster than the speed of sound), which the researchers say is a world record in self-acting air bearing technology.

The speed of air bearings is usually limited by instabilities, but the researchers solved this problem by developing a special damping mechanism. Moreover, in contrast to aerostatic air bearings, which operate on a compressed-air supply, this air bearing is aerodynamic, and thus develops sufficient bearing pressure from its own rotation. This means the self-pressurising system can operate autonomously.

These high-speed bearings will be suitable for use in turbos, small gas turbines, compressors and micro-milling cutters. Turbos that operate with air bearings have less friction and are thus more efficient than the current types, which use oil bearings or ball bearings. Using these bearings in compressors ensures oil-free compressed air, which is important for applications in the medical sector and food industry.

Small gas turbines can be used for domestic co-generation and as auxiliary engines for electric cars.

For more information, visit the project’s page at: http://www.powermems.be/Pen_setup.html