Excitation of airborne acoustic surface modes driven by a turbulent flow
Damani, S; Totten, E; Davies, L; et al.Alexander, WN; Devenport, WJ; Pearce, BP; Shelley, SR; Starkey, TA; Hibbins, AP; Sambles, JR
Date: 8 June 2020
Conference proceedings
Publisher
American Institute of Aeronautics and Astronautics (AIAA)
Publisher DOI
Abstract
This experiment demonstrated the generation of trapped acoustic surface waves
excited by a turbulent flow source through the coupling of pressure fluctuations at
the interface between an acoustic metamaterial and a flow environment. The
turbulent flow, which behaves as a stochastic pressure source, was produced using a
fully developed ...
This experiment demonstrated the generation of trapped acoustic surface waves
excited by a turbulent flow source through the coupling of pressure fluctuations at
the interface between an acoustic metamaterial and a flow environment. The
turbulent flow, which behaves as a stochastic pressure source, was produced using a
fully developed turbulent wall jet. The plate in the wall jet was perforated with a
single cavity. On the flow-side it was capped by a Kevlar weave to ensure the cavity
did not significantly disturb the flow, whilst on the adjacent side the cavity was open
to the quiescent (static) environment. The through-cavity opening, on the quiescent
side, was flush with an acoustic metasurface waveguide, which, through evanescent
diffractive coupling of the pressure field, produced an acoustic surface mode. This
acoustic mode was trapped at the plate surface, with its mode dispersion determined
by the surface geometry. The results of two different metasurface geometries are
discussed; (1) a slotted cavity array, and (2) a meander connected cavity array, each
demonstrating a different trapped surface wave dispersion behavior. Fourier
transform and correlation analyses of spatially-resolved temporal acoustic signals,
measured close to the metamaterial surface, were used to construct the frequency
and wave vector-dependent acoustic mode dispersion. Results demonstrated the flow
can indeed be used to excite these acoustic modes and that their mode dispersion can
be tailored towards realizing novel control of turbulent flow through acoustic-flow
interactions
Physics and Astronomy
Faculty of Environment, Science and Economy
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