On Predicting Aeroacoustic Performance of Ducts with Broadband Noise Source Models

Khondge, Ashok; Sovani, Sandeep; Kim, Sang Hoon; Guzy, Steven C.; Farag, Ashraf

doi:10.4271/2005-01-2495

Cited by 6 publications

(3 citation statements)

References 14 publications

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“…In researches conducted by Santos (1995), Khondge et al (2005), Ayar et al (2005), Mohamud and Johnson (2006), Croaker et al (2011), Junger (2019, the Proudman's Formula Model (Proudman 1952) and the Boundary Layer Noise Source Model (Curle 1955) are used and presented as a low-cost computational tool to identify the main noise sources, which represents an attractive option to quickly and inexpensively evaluate the acoustic performance, especially in the design phase, as it allows optimizing the parameters related to the main sources of noise.…”

Section: Aeroacoustics Behavior -Aeroacoustics Sourcesmentioning

confidence: 99%

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Free and Non-Free Vortex Design for Axial Fans with Circumferential Sweep through CFD Techniques

2022

JAFM

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The sound generated by axial flow fans has become increasingly important in several industrial areas. These devices represent considerable noise sources that must be considered from the design stage. The scope of this research work is to present an axial fan design methodology based on the theory of the wing lift and to compare the aerodynamic and aeroacoustics behavior with the free vortex and the non-free vortex conditions. The effect of forward circumferential sweep on the rotor blades is analyzed in both conditions, which consists of a displacement in the tangential direction in the direction of rotor rotation. A cubic polynomial function is proposed for the construction of the blade geometry with circumferential sweep. It defines the center line of the blade and it is taken at 50% of the leading edge of each blade profile. The methodology for analyzing aeroacoustics behavior in fans is based on the integration of Computational Aeroacoustics and Computational Fluid Dynamics in order to analyze aerodynamic behavior, sound power level and sound pressure level at the preliminary design stage. It was verified that although both rotors present a similar aerodynamic behavior (the NFV rotor has a slightly lower performance), according to the analysis of local sound sources, the NFV rotor presents a slight decrease in the sound sources. It was also verified that the NFV rotor presents 2.2 dB less in sound pressure level than the FV rotor.

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Section: Aeroacoustics Behavior -Aeroacoustics Sourcesmentioning

confidence: 99%

“…( 47). The mean-square time-derivative of the surface pressure and the correlation area are further approximated in terms of turbulent quantities like turbulent kinetic energy, dissipation rate, and wallshear (Khondge et al 2005).…”

Section: Aeroacoustics Behavior -Aeroacoustics Sourcesmentioning

confidence: 99%

Free and Non-Free Vortex Design for Axial Fans with Circumferential Sweep through CFD Techniques

2022

JAFM

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“…Leclercq and Symes compared experimental work and numerical implementation of Curle's integral of bluff bodies in fluctuating flow field [33]. Khondge et al applied BNS models to predict aeroacoustics performance of a duct and found that predicted noise was directionally supported by experimental data [34].…”

Section: Introductionmentioning

confidence: 99%

Simulation of Broadband Noise Sources of an Axial Fan under Rotating Stall Conditions

Zhang

Wang

2014

Advances in Mechanical Engineering

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Study on the influence of rotating stall on the aerodynamic noise of axial fan has important value to warn of the occurrence of stall through monitoring the noise variations. The present work is to analyze the aerodynamic noise before and after the phenomenon of rotating stall by solving Navier-Stokes equations, coupled with the throttle condition and the broadband noise sources model. The impeller exit rotational Mach number and rotational Reynolds number are separately 0.407 and 8.332 × 106 . The results show that the aerodynamic noise source of the fan is mainly the rotation noise under the design condition. The vortex noise accounts for the major part of fan noise after the occurrence of stall, and the maximum acoustic power level of the fan appears in the rotor domains. In the evolution process from the stall inception to the stall cell, the high noise regions of the rotor develop along the radial, circumferential, and axial directions, and the area occupied by high noise regions increases from 33% to 46% impeller channels area. On rotating stall condition, the high noise regions occupying about 46% impeller channels area propagate with the stall cell along the circumferential direction at a half of rotor speed.

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Axial‐Symmetry Numerical Approaches for Noise Predicting and Attenuating of Rifle Shooting with Suppressors

Tai

Teng

2011

Journal of Applied Mathematics

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The moving bullet out of a rifle barrel is propelled by a fired explosive charge. Subsequently, a disturbed muzzle blast wave is initiated which lasts several milliseconds. In this study, axially symmetric, unsteady, Large Eddy Simulation (LES), and Ffowcs Williams and Hawkins (FWH) equations were solved by the implicit-time formulation. For the spatial discretization, second order upwind scheme was employed. In addition, dynamic mesh model was used to where the ballistic domain changed with time due to the motion of bullet. Results obtained for muzzle flow field and for noise recorded were compared with those obtained from experimental data; these two batches of results were in agreement. Five cases of gunshot including one model of an unsuppressed rifle and four models of suppressors were simulated. Besides, serial images of species distributions and velocity vectors-pressure contours in suppressors and near muzzle field were displayed. The sound pressure levels (dB) in far field that were post-processed by the fast Fourier transform (FFT) were compared. The proposed physical model and the numerical simulations used in the present work are expected to be extended to solve other shooting weapon problems with three-dimensional and complex geometries.

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On Predicting Aeroacoustic Performance of Ducts with Broadband Noise Source Models

Cited by 6 publications

References 14 publications

Free and Non-Free Vortex Design for Axial Fans with Circumferential Sweep through CFD Techniques

Free and Non-Free Vortex Design for Axial Fans with Circumferential Sweep through CFD Techniques

Simulation of Broadband Noise Sources of an Axial Fan under Rotating Stall Conditions

Axial‐Symmetry Numerical Approaches for Noise Predicting and Attenuating of Rifle Shooting with Suppressors

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