0
Research Papers: Fundamental Issues and Canonical Flows

Acoustic Power Calculation in Deep Cavity Flows: A Semiempirical Approach

[+] Author and Article Information
P. Oshkai1

Department of Mechanical Engineering, University of Victoria, P.O. Box 3055 STN CSC, Victoria, BC, Canada, V8W 3P6poshkai@me.uvic.ca

T. Yan, A. Velikorodny, S. VanCaeseele

Department of Mechanical Engineering, University of Victoria, P.O. Box 3055 STN CSC, Victoria, BC, Canada, V8W 3P6

1

Corresponding author.

J. Fluids Eng 130(5), 051203 (May 01, 2008) (9 pages) doi:10.1115/1.2907413 History: Received July 12, 2007; Revised February 08, 2008; Published May 01, 2008

Acoustic power generated by turbulent flow over a coaxial side branch (deep cavity) resonator mounted in a rectangular duct is calculated using a semiempirical approach. Instantaneous flow velocity is decomposed into an irrotational acoustic component and vorticity-bearing hydrodynamic field. The total velocity at several phases of the acoustic oscillation cycle is measured using digital particle image velocimetry. The acoustic velocity field is numerically calculated. The emphasis is on the effect of the accurate geometry representation for the acoustic field modeling on the calculated acoustic power. Despite the generally low levels of acoustic radiation from the coaxial side branches, when the main duct is incorporated into the model for calculation of the acoustic velocity, the acoustic velocity exhibits substantial horizontal (streamwise) components in the vicinity of the cavity corners. This streamwise acoustic velocity correlates with hydrodynamic horizontal velocity fluctuations, thus contributing to the calculated acoustic power. Spatial structure and strength of the acoustic source change as the distance between the side branches varies. Global quantitative imaging approach is used to characterize the transformation of the acoustic source structure in terms of patterns of instantaneous and phase-averaged flow velocity, vorticity, and streamline topology as well as time-averaged acoustic power.

FIGURES IN THIS ARTICLE
<>
Copyright © 2008 by American Society of Mechanical Engineers
Your Session has timed out. Please sign back in to continue.

References

Figures

Grahic Jump Location
Figure 2

Computational domain and boundary conditions

Grahic Jump Location
Figure 10

Patterns of time-averaged acoustic power corresponding to the first hydrodynamic oscillation mode: (a) D∕L=0.5; (b) D∕L=0.25

Grahic Jump Location
Figure 1

Schematic of the coaxial side branch resonator

Grahic Jump Location
Figure 3

Close-up of the computational mesh in the cross-junction region

Grahic Jump Location
Figure 4

Resonant acoustic mode shapes: (a) first mode (f=175Hz); (b) third mode (f=527Hz); (c) fifth mode (f=879Hz)

Grahic Jump Location
Figure 5

Three-dimensional representation of pressure amplitude as a function of frequency and flow velocity: (a) D∕L=0.5; (b) D∕L=0.25

Grahic Jump Location
Figure 6

Instantaneous flow patterns corresponding to the first hydrodynamic oscillation mode (D∕L=0.5, Sr=0.34, Uac∕U=0.0005)

Grahic Jump Location
Figure 7

Instantaneous flow patterns corresponding to the first hydrodynamic oscillation mode (D∕L=0.25, Sr=0.28, Uac∕U=0.001)

Grahic Jump Location
Figure 8

Phase-averaged flow patterns corresponding to the first hydrodynamic oscillation mode at φ=10deg

Grahic Jump Location
Figure 9

Amplitude of the horizontal and the vertical components of acoustic velocity (D∕L=0.5): (a) (Uac)x; (b) (Uac)y

Grahic Jump Location
Figure 11

Patterns of time-averaged acoustic power corresponding to the second hydrodynamic oscillation mode. (a) D∕L=0.5; (b) D∕L=0.25

Tables

Errata

Discussions

Some tools below are only available to our subscribers or users with an online account.

Related Content

Customize your page view by dragging and repositioning the boxes below.

Related Journal Articles
Related eBook Content
Topic Collections

Sorry! You do not have access to this content. For assistance or to subscribe, please contact us:

  • TELEPHONE: 1-800-843-2763 (Toll-free in the USA)
  • EMAIL: asmedigitalcollection@asme.org
Sign In