Investigation Of Acoustically Coupled Shear
Layers Using Particle Image Velocimetry
Author(s)
P. Oshkai, T. Yan & A. Howard
Abstract
Quantitative visualization of acoustically coupled shear layers that are formed
due to fully turbulent inflow past a coaxial side branch resonator mounted in a
duct is performed using a technique of digital particle image velocimetry.
Imaging of the flow structure conducted in conjunction with unsteady pressure
measurements leads to patterns of velocity, vorticity, and streamline topology at
various phases of the acoustic cycle. Global instantaneous images, as well as
time-averaged images, are evaluated to provide insight into the flow physics
during tone generation. In particular, the effect of the interaction between two
shear layers that form across the coaxial side branches on the acoustic power
generation is studied for various resonator geometries.
Keywords: flow-acoustic coupling, shear layer interaction, coaxial side branch
resonators, acoustic power.
1 Introduction
Internal flow past a deep cavity (side branch) mounted in a duct is often
characterized by the coupling between the self-sustained oscillations of the
separated shear layer that forms across the mouth of the cavity and the resonant
acoustic modes of the side branch. This resonant phenomenon, which occurs in
many industrial processes involving transport of a fluid through a pipeline and is
referred to as flow tone generation, involves high-amplitude pressure pulsations
and flow oscillations.
Flow tone generation past multiple side branches has been a subject of many
investigations, as summarized by Ziada and Bühlmann [1]. Classification of side
branch resonances as fluid-resonant oscillations was performed by Rockwell and
Naudascher [2]. Generally speaking, if the frequency of the shear layer
Keywords
flow-acoustic coupling, shear layer interaction, coaxial side branch
resonators, acoustic power.
Related Book
Other papers in this volume
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