Characteristics of flow regimes for two plates of rectangular cross-section in tandem

Abstract

Flow characteristics including velocity fluctuations, acoustic pressure fluctuations and surface pressures have been investigated for two plates in a tandem array at high Reynolds numbers. The plates were of rectangular cross section and of the same thickness, having and a range of chord-to-thickness ratios with a range of gap-to-thickness ratios between them. The flow measurements were complemented with hydrogen-bubble flow visualisation. A classification of possible flow regimes is proposed and confirmed experimentally. For very small separations the two plates behave as a single plate. Symmetrical vortex shedding is detected even for the configurations with larger separation. For the upstream plates in the single plate regime, where frequency components lower than the characteristic shedding frequency are present, these components are amplified in the presence of a downstream plate. They are clearly detectable in velocity and pressure measurements and can become dominant in the acoustic spectra.