Oscillations of flow past perforated and slotted plates: attenuation via a leading-edge ramp |
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Authors: | E Celik A C Sever T Kiwata D Rockwell |
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Institution: | (1) Department of Mechanical Engineering and Mechanics, 356 Packard Laboratory, Lehigh University, 19 Memorial Drive West, Bethlehem, PA 18015, USA |
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Abstract: | The present investigation aims to attenuate purely hydrodynamic, long-wavelength, self-excited oscillations of flow past a
perforated or slotted plate by deflection of the inflow with a small ramp located at the leading-edge of the plate. Digital
particle image velocimetry is complemented by unsteady pressure measurements to determine the underlying physics associated
with attenuation of the oscillations. Irrespective of whether a perforated or slotted plate is employed, complete attenuation
of the pressure fluctuations associated with the oscillation can be achieved for dimensionless deflection ratios of h/L ≥ 0.035, in which h is the height of the ramp and L is the effective plate length. The attenuation of the self-excited oscillation involves: a steady jet at the trailing-edge
of the plate directed into the cavity; a lower magnitude upstream-oriented counterflow along the backside of the plate; and
jet-like flows through the plate openings to satisfy the entrainment demands of the separating shear layer. |
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