Standing wave and its impact on the low-frequency pressure fluctuation in an open jet wind tunnel

Abstract

Experiments and numerical studies of the low-frequency pressure pulsation in an open jet wind tunnel were conducted. Measuring the pressure pulsation in the wind tunnel’s plenum, demonstrated that the low-frequency pressure pulsation was a standing wave along plenum’s horizontal direction. By numerically simulating plenums with different widths, we found that the pressure fluctuation reached the maximum when standing wave’s frequency approached edge-tone feedback’s frequency. The organized vortex structures in the two shear layers around the jet in the horizontal direction were antisymmetrically arranged. We propose that the low-frequency fluctuation in the plenum originated from the resonance between the edge-tone feedback (generated by the vortex-acoustic feedback between the nozzle and the collector) and the standing wave. The mechanism of resonance was analyzed and possible remedies are suggested in this paper.