The empirical investigation of the spatial distribution of resonant acoustic sources around a tandem cylinder configuration subject to cross flow in a duct and an imposed transverse acoustic wave is described. The imposed wave induced acoustic “lock-in” and the vortex shedding frequency from the cylinders became entrained to the frequency of the imposed wave near acoustic-Strouhal coincidence. Howe’s aeroacoustic theory was used to couple an acoustic field to a hydrodynamic flow field and the spatial distribution of the time-resolved acoustic power and net-acoustic energy throughout a complete acoustic wave cycle at two resonant conditions were calculated. The first resonant condition occurred at a low flow velocity before acoustic-Strouhal coincidence, whilst the second occurred at a higher flow velocity just after acoustic-Strouhal coincidence. The acoustic field was analysed using finite element analysis combined with microphone pressure measurements whilst the hydrodynamic flow field was extracted using particle image velocimetry from a field of view concentrated around the cylinders and roughly three diameters downstream of them. For both resonant conditions, the dominant individual sources were found to lie in the shear layers of the gap region between the cylinders, however, stronger individual sinks were found to be located there also. Thus, for the amplitude of the applied sound wave and for the available field of view, the gap shear layer region contributed an overall acoustic sink whilst the wake contributed an overall acoustic source.
Experimental Investigation of the Aeroacoustic Sources in a Tandem Cylinder Configuration
Finnegan, SL, Meskell, C, & Ziada, S. "Experimental Investigation of the Aeroacoustic Sources in a Tandem Cylinder Configuration." Proceedings of the ASME 2009 Pressure Vessels and Piping Conference. Volume 4: Fluid-Structure Interaction. Prague, Czech Republic. July 26–30, 2009. pp. 399-408. ASME. https://doi.org/10.1115/PVP2009-77757
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