Jr. Frederick et Ms. Darlow, OPERATION OF AN ELECTROMAGNETIC EDDY-CURRENT DAMPER WITH A SUPERCRITICAL SHAFT, Journal of vibration and acoustics, 116(4), 1994, pp. 578-580
A basic problem inherent with the operation of supercritical shafting
is the application of appropriate external damping, which is generally
necessary to suppress nonsynchronous instabilities and limit the sync
hronous response of even a well-balanced shaft. Typically, coulomb or
squeeze film-type dampers are used, in which case the damping properti
es tend to change with temperature, and the necessary contact results
in additional torque loading and wear. An alternative damping method c
urrently under investigation is the application of a noncontact electr
omagnetic damper that dissipates energy through induced eddy-currents
generated in a small disk mounted to, and rotating with the shaft (Fre
derick, 1990). Research is underway on the design and development of a
damper of this type that could eventually lend itself to active contr
ol applications. The objectives of this investigation are the initial
design of a magnetic circuit, an appropriate d-c power supply, and the
characterization of preliminary performance experiments on a composit
e shaft. Damper operation was evaluated during rotating shaft tests an
d compared to prior tests which involved the use of a permanent magnet
eddy-current damper. This Note concerns some interesting results obta
ined from these preliminary tests. The damper worked well at low speed
s, but some high-speed stability problems were encountered. Potential
solutions to these problems as well as areas of future research are di
scussed.