A computer program controls the automated acquisition, display, and reduction of data on the dynamics of magnetic bearings. The data gathered by use of this program are expected to enable the verification and enhancement of mathematical models of magnetic-bearing dynamics, thereby contributing to the development of improved magnetic bearings for advanced gas turbine engines and other rotary machines.

With respect to a given magnetic bearing that is part of a rotary machine, the program acquires raw data on rotor position versus time during operation of the machine under known conditions of speed of rotation, temperature, electric currents applied to the electromagnet coils in the bearing, and shaking. The program processes the raw data to characterize the bearing with respect to dynamic position stiffness, current stiffness, and damping coefficients versus speed of rotation, eccentricity, bias current, temperature, and frequency of shaking. The program can also account for friction, stiffnesses of structural supports, inertia, and uncertainties.

The program was developed by use of the LabVIEW software system and the corresponding NI-DAQ programming language. The program provides the user with four major options called "16 Time," "16 Frequency," "Stiffness," and "Alignment." The first two options enable the monitoring of 16 analog input channels to obtain time- and frequency-domain responses. These options also enable the generation of four orbit displays and provide for the recording, in a text file, of the magnitudes and phases of the components of motion at the shaking frequency. The Stiffness option provides for the measurement and recording of the position and the current stiffness of the magnetic bearing, using data from 14 input channels. The stiffness option also includes a provision for calculating uncertainties. The Alignment option generates a graphical display of stator alignment with a bar chart of eight dynamic load cells.

This program was written by Gerald Montague and Al Kascak of the U.S. Army Research Laboratory and Alan Palazzolo of Texas A & M University for Glenn Research Center. For further information, access the Technical Support Package (TSP) free on-line at www.nasatech.com/tsp  under the Software category.

Inquiries concerning rights for the commercial use of this invention should be addressed to

NASA Glenn Research Center
Commercial Technology Office
Attn: Steve Fedor
Mail Stop 4 —8
21000 Brookpark Road
Ohio 44135.

Refer to LEW-17057.

NASA Tech Briefs Magazine

This article first appeared in the November, 2000 issue of NASA Tech Briefs Magazine.

Read more articles from the archives here.