Energy dissipation due to sloshing liquid in torus shaped nutation dampers is studied experimentally. An extensive test program with the dampers undergoing steady-state oscillatory translation is undertaken to establish the optimal parameters. Low liquid heights and large diameter ratios with the system operating at the liquid sloshing resonance are shown to result in increased damping. Tests with two and three dimensional models in laminar flow and boundary layer wind tunnels suggest that the dampers can successfully control both vortex resonance and galloping type of instabilities. A design procedure for application of the damper to three distinct situations:
full scale smokestacks undergoing vortex resonance;
wave excited oscillations of offshore marine risers; and
horizontal pipelines; is discussed in some detail.
The information should prove useful, particularly, in damping low frequency oscillations.
Vibration of mechanical systems is a universal phenomenon extending to space, atmosphere, earth and ocean based structures. Suppression of mechanical oscillations, forced or self-excited, or at least their minimization to an acceptable level, is a challenge faced by engineers. Librational vibrational instabilities of satellites with large flexible appendages in the form of solar panels, antennas and booms are of interest to space engineers. With the U.S. commitment to the Space Station, a highly flexible gigantic structure with the fundamental natural frequency less than 0.1 Hz, the problems of vibration damping in space environment have become of prime concern. Of course, the classical problems of flutter and divergence of aerodynamic surfaces operating in continuum aerodynamic field are still with us. Coming back to earth, we are literally swamped by a host of problems arising from a variety of diverse sources. Broadly speaking they may be classified as: