Abstract

The Behaviour of the Acoustic Gyrometers for Transient and High Rotation Rates

M.Bruneau, D.Ecotiere, N.Tahani (Laboratoire d'Acoustique de l'Universite du Maine, UMR CNRS 6613, Universite du Maine, Le Mans, France.)

e-mail: michel.bruneau@univ-lemans.fr

Acoustic rate gyros provide output signals that are measures of rotation rates with respect to an inertial frame. They involve both inertial and flow-induced acoustic modes coupling inside rotating cylindrical fluid-filled resonant cavities, the former occurring for transient and stationary rotation of the device, the latter occurring only for the transient rotation. The vortical component of the particle velocity is involved in the process, emphasising the important role plays by the viscous boundary layers. Recent researches aimed at investigating the behaviour of the acoustic gyros for unsteady circular flow which occurs when the cavity is set in rotation around its axis. Moreover, current investigations are focusing on the behaviour of the gyros for very high angular velocities that give rise to non linear effects (with respect to the rotation rate), namely the effects of the non uniform properties of the fluid on the acoustic field and the recurrent inertial coupling between the preponderant acoustic modes. The results provide methods for designing this new kind of acoustic rate gyros, which involve lower power consumption and manufacturing cost, improved reliability and live time, short transient response and high dynamic range.

Section : 7