Unsteady pressure measurements on an oscillating cylinder in narrow annular flow

Abstract

This paper describes experiments on the unsteady pressure field generated in annular flowwhen the central cylinder (centre-body) in the annulus is subjected to angular oscillations about a hinge. The oscillations were generated by a shaker and the fluid was air. The unsteady pressure was measured differentially on two diametrally opposed points in the annulus, in the plane of oscillation, on both the oscillating centre-body and on the coaxial outer duct, by means of a sensitive pressure transducer; the angular oscillation was measured by an internally mounted accelerometer. Both accelerometer and pressure-transducer signals were processed through an FFT signal analyser. Experiments were conducted for various positions of the hinge, frequencies of oscillation and flow velocities, and measurements taken along the length of the centre-body. Agreement between the measured pressure and theoretical values obtained from a previously developed theory was good, except near the body extremities, where end effects” related to the peculiarities of the apparatus come into play.