Theory for hydrostatic gas journal bearings for micro-electro-mechanical systems

The goal of the MIT micro-engine project is to develop high-speed rotating Power MEMS (Micro-Electro-Mechanical Systems) using computer chip fabrication technologies. To produce high power (10-50 W) in a small volume (less than one cubic centimeter), the micro-turbo-machinery must be spun at a rotational speed on the order of million rpm. This ultra-high rotational speed, together with the small length-to-diameter ratio (L/D<0.07) limited by the chip manufacturing technology, entails many challenges in the design of the bearing system, such as an ultra-high whirl ratio of over 20 (compared with a whirl ratio of 2 for large-scale journal bearings) and a DN number of order 10 million mm-rpm. The thesis presents a newly developed theory for the hydrostatic gas journal- bearings for the micro-engine devices. To investigate the underlying physical mechanisms, fluid models are established to analytically calculate the hydrostatic, hydrodynamic, and damping bearing forces. It is found from first principles that the hydrodynamic force due to viscous drag becomes dominant with an L/D<<1 and acts in the opposite direction of the hydrodynamic force due to rotor pumping action.

Department dc:contributor.department

Massachusetts Institute of Technology. Department of Mechanical Engineering

Grantor dc:publisher

Massachusetts Institute of Technology

Year dc:date.issued

2005

Author dc:creator

• Liu, Lixian, Ph. D. Massachusetts Institute of Technology

Advisor dc:contributor.advisor

• Zoltan S. Spakovszky.

• Mechanical Engineering.

Statement dc:rights

• M.I.T. theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. See provided URL for inquiries about permission.

Licence dc:rights.uri

• http://dspace.mit.edu/handle/1721.1/7582

Language dc:language.iso

eng

Handle dc:identifier.uri

http://hdl.handle.net/1721.1/33921

OAI identifier oai:identifier

oai:dspace.mit.edu:1721.1/33921