caa a22 4500 606198296 CHVBK 20210128100933.0 cr unu---uuuuu 210128e20150401xx s 000 0 eng 10.1007/s00348-015-1908-8 doi (NATIONALLICENCE)springer-10.1007/s00348-015-1908-8 Passive control of flow-excited acoustic resonance in rectangular cavities using upstream mounted blocks [Elektronische Daten] [Mahmoud Shaaban, Atef Mohany] A passive method for controlling the flow-excited acoustic resonance resulting from subsonic flows over rectangular cavities in channels is investigated. A cavity with length to depth ratio of $$L/D=1$$ L / D = 1 is tested in air flow of Mach number up to 0.45. When the acoustic resonance is excited, the sound pressure level in the cavity reaches 162dB. Square blocks are attached to the surface of the channel and centred upstream of the cavity leading edge to suppress the flow-excited acoustic resonance in the cavity. Six blocks of different widths are tested at three different upstream distances. The results show that significant attenuation of up to 30 dB of the excited sound pressure level is achieved using a block with a width to height ratio of 3, while blocks that fill the whole width of the channel amplify the pressure of the excited acoustic resonance. Moreover, it is found that placing the block upstream of the cavity causes the onset of the acoustic resonance to occur at higher flow velocities. In order to investigate the nature of the interactions that lead to suppression of the acoustic resonance and to identify the changes in flow patterns due to the placement of the block, 2D measurements of turbulence intensity in the shear layer and the block wake region are performed. The location of the flow reattachment point downstream of the block relative to the shear layer separation point has a major influence on the suppression level of the excited acoustic resonance. Furthermore, higher attenuation of noise is related to lower span-wise correlation of the shear-layer perturbation. Springer-Verlag Berlin Heidelberg, 2015 Shaaban Mahmoud Aeroacoustics and Noise Control Laboratory, Faculty of Engineering and Applied Science, University of Ontario Institute of Technology, Oshawa, ON, Canada aut Mohany Atef Aeroacoustics and Noise Control Laboratory, Faculty of Engineering and Applied Science, University of Ontario Institute of Technology, Oshawa, ON, Canada aut Experiments in Fluids Springer Berlin Heidelberg 56/4(2015-04-01), 1-12 0723-4864 56:4<1 2015 56 348 https://doi.org/10.1007/s00348-015-1908-8 text/html Onlinezugriff via DOI BK010053 XK010053 XK010000 Metadata rights reserved Springer special CC-BY-NC licence nationallicence 1 research-article jats NATIONALLICENCE NATIONALLICENCE NL-springer NATIONALLICENCE 856 40 https://doi.org/10.1007/s00348-015-1908-8 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Shaaban Mahmoud Aeroacoustics and Noise Control Laboratory, Faculty of Engineering and Applied Science, University of Ontario Institute of Technology, Oshawa, ON, Canada aut NATIONALLICENCE 700 1- Mohany Atef Aeroacoustics and Noise Control Laboratory, Faculty of Engineering and Applied Science, University of Ontario Institute of Technology, Oshawa, ON, Canada aut NATIONALLICENCE 773 0- Experiments in Fluids Springer Berlin Heidelberg 56/4(2015-04-01), 1-12 0723-4864 56:4<1 2015 56 348