A 4.2-mm diameter silicon rotor has been operated in a controlled and sustained manner at rotational speeds greater than 1.3 million rpm and power levels approaching 5 W. The rotor, supported by hydrostatic journal and thrust gas bearings, is driven by an air turbine. This turbomachinery/bearing test device was fabricated from single-crystal silicon wafers using micro-fabrication etching and bonding techniques. We believe this device is the first micro-machine to operate at a circumferential tip speed of over 300 meters per second, comparable to conventional macroscale turbomachinery, and necessary for achieving high levels of power density in micro-turbomachinery and micro-electrostatic/ electromagnetic devices. To achieve this level of peripheral speed, micro-fabricated rotors require stable, low-friction bearings for support. Due to the small scale of these devices as well as fabrication constraints that limit the bearing aspect ratio, the design regime is well outside that of more conventional devices. This paper focuses on bearing design and test, and rotordynamic issues for high-speed high-power micro-fabricated devices.

Issue Section:
Gas Turbines: Structures and Dynamics
Keywords:
machine bearings, gas turbines, rotors, micromechanical devices, product development, design engineering, velocity, silicon
Topics:
Bearings, Design, Journal bearings, Manufacturing, Rotors, Semiconductor wafers, Hydrostatics, Thrust bearings, Silicon, Gas bearings, Turbines
1.
Epstein, A. H., et al., 1997, “Micro-Heat Engines, Gas Turbines, and Rocket Engines—The MIT Microengine Project,” 28th AIAA Fluid Dynamics Conference, 4th AIAA Shear Flow Control Conference, Snowmass Village, CO, AIAA Paper No. 97-1773.
2.
Epstein, A. H., Sentura, S. D., Waitz, I. A., Lang, J., Jacobson, S. A., Ehrich, F. F., Schmidt, M. A., Ananthasuresh, G. K., Spearing, M. S., Breuer, K. S., and Nagle, S., 1998, “Microturbomachinery,” World Intellectual Property Organization, International Publication Number WO 98/02643 and U.S. Patent #5,932,940.
3.
Jacobson, S. A., 1998, “Aerothermal Challenges in the Design of a Microfabricated Gas Turbine Engine,” AIAA Paper No. 98-2545.
4.
Breuer, K. S., Ehrich, F. F., Fre´chette, L., Jacobson, S., Orr, D. J., Piekos, E., Savoulides, N., and Wong, C. W., 2000, “Challenges for Lubrication in High Speed MEMS,” NanoTribology, Stephen Hsu, ed., Kluwer, Dordrecht, The Netherlands.
5.
Chen, K. S., 1999, “Materials Characterization and Structural Design of Ceramic Micro Turbomachinery,” Ph.D. thesis, Department of Aeronautics and Astronautics, M.I.T., Cambridge, MA.
6.
Spearing, S. M., and Chen, K. S., 1997, “Micro-Gas Turbine Materials and Structures,” presented at 21st Annual Cocoa Beach Conference and Exposition on Composites, Advanced Ceramics, Materials and Structures.
7.
Lin, C. C., Ghodssi, R., Ayon, A. A., Chen, D. Z., Jacobson, S., Breuer, K. S., Epstein, A. H., and Schmidt, M. A., 1999, “Fabrication and Characterization of a Micro Turbine/Bearing Rig,” MEMS ’99, Orlando, FL, Jan.
8.
Fre´chette, L. G., Jacobson, S. A., Breuer, K. S., Ehrich, F. F., Ghodssi, R., Khanna, R, Wong, C. W., Zhang, X., Schmidt, M. A., and Epstein, A. H., 2000, “Demonstration of a Microfabricated High-Speed Turbine Supported on Gas Bearings,” Solid-State Sensor and Actuator Workshop, Hilton Head Island, SC.
9.
Protz, J. M., 2000, “An Assessment of the Aerodynamic, Thermodynamic, and Manufacturing Issues for the Design, Development, and Microfabrication of a Demonstration Microengine,” Ph.D. Thesis, Department of Aeronautics and Astronautics, M.I.T., Cambridge, MA.
10.
Wong, C. W., 2001, “Design, Fabrication, Experimentation and Analysis of High-Speed Microscale Gas Bearings,” M. S. thesis, Department of Mechanical Engineering, M.I.T., Cambridge, MA.
11.
Orr, D. J., 2000, “Macro-Scale Investigation of High Speed Bearings for MEMS Devices,” Ph.D. thesis, Department of Aeronautics and Astronautics, M.I.T., Cambridge, MA.
12.
Piekos, E. S., Orr, D. J., Jacobson, S. A., Ehrich, F. F., and Breuer, K. S., 1997, “Design and Analysis of Microfabricated High Speed Gas Journal Bearings,” 28th AIAA Fluid Dynamics Conference, 4th AIAA Shear Flow Control Conference, Snowmass Village, CO, AIAA Paper 97-1966.
13.
Piekos, E. S., and Breuer, K. S., 1998, “Pseudospectral Orbit Simulation of Non-Ideal Gas Lubricated Journal Bearings for Microfabricated Turbomachines,” ASME Paper No. 98-Trib-48.
14.
Piekos, E. S., 2000, “Numerical Simulation of Gas-Lubricated Journal Bearings for Microfabricated Machines,” Ph.D. thesis, Department of Aeronautics and Astronautics, M.I.T., Cambridge, MA.
15.
Ayon
,
A. A.
,
Braff
,
R.
,
Lin
,
C. C.
,
Sawin
,
H. H.
, and
Schmidt
,
M. A.
,
1999
, “
Characterization of a Time Multiplexed Inductively Coupled Plasma Etcher
,”
J. Electrochem. Soc.
,
146
(
1
), pp.
339
–
349
.
16.
Childs, D. W., 1993, Turbomachinery Rotor Dynamics, John Wiley and Sons, New York, Chap. 4 and 5.
17.
Ehrich
,
F. F.
,
1995
, “
Nonlinear Phenomena in Dynamic Response of Rotors in Anisotropic Mounting Systems
,”
ASME J. Vibr. Acoust.
,
118
, pp.
154
–
161
.
18.
Breuer, K. S., 1999, personal communication.
19.
Tang
,
I. D.
, and
Gross
,
W. A.
,
1962
, “
Analysis and Design of Externally Pressurized Gas Bearings
,”
ASLE Trans.
,
5
, pp.
261
–
284
.
20.
Larson
,
R. H.
, and
Richardson
,
H. H.
,
1962
, “
A Preliminary Study of Whirl Instability for Pressurized Gas Bearings
,”
ASME J. Basic Eng.
,
84
.
Copyright © 2003
 by ASME
You do not currently have access to this content.