VORTICITY SHEDDING AND ACOUSTIC-RESONANCE IN AN IN-LINE TUBE BUNDLE .1. VORTICITY SHEDDING

An in-line tube array with intermediate tube spacings was tested in a wind tunnel and a water channel. Extensive flow visualization and correlation measurements were carried out to reveal the nature of the vorticity-shedding excitation. The instability of the jet issuing between the tubes is found to be the source of the vorticity-shedding excitation. The jet instability occurs at its symmetric mode, whereupon large-scale vortices are formed symmetrically on both sides of each flow lane. Since the jet instability in each flow lane is 180° out of phase with that in the neighbouring lanes, vortices are formed antisymmetrically in the tube wakes. © 1992.