G, Pradeep and T, Thanigaivel Raja and D, Veerababu and B, Venkatesham
(2017)
Numerical Prediction of Perforated tube acoustic impedance.
In: 24th International Conference on Sound and Vibration, London, 23-27 July, 2017.
Abstract
The
use of perforated
sheets is very common in noise control applications such as mufflers, aero
-
engines,
building acoustics and heating ventilation and air
-
conditioning systems. The acoustic performance of
these liners is expressed mathematically in terms of its impedance.
Th
ere is
a
great
amount of literature
available to estimate the liner impedance. Most of the models are semi
-
empirical in nature and derived
from experimental studies. Geometric parameters like orifice diameter,
plate
thickness, cross
-
sectional
dimension, ho
le distribution pattern, operating flow conditions and sound pressure levels play a critical
role in perforated tube impedance estimations.
In this work,
a numerical methodology
was developed
based on Finite
-
Element Methods, to estimate the impedance of pe
rforated
plate
and validated with
existing literature results for stationary flow conditions. Perforated
plate
inside the circular tube is
considered
as
a
computational
acoustic domain. Plane wave excitation is applied as the inlet boundary
condition at on
e end of the tube
, anechoic termination is applied as the outlet boundary condition
and
the rest of the e
xterior domain
is assumed to be acoustically rigid.
This methodology has been extended
to evaluate the impedance of perforated tubes. Parametric
studies are conducted to study the curvature
effect of perforated tubes on impedance,
by changing the tube diameter.
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