Reduction of centrifugal fan noise by use of resonators

Neise, W.; Koopmann, Gary H.

doi:10.1016/0022-460x(80)90697-5

Cited by 45 publications

(17 citation statements)

References 9 publications

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“…Its value is found by Proudman to be dependent on the shape of the longitudinal velocity scalar correlation function, ( / ). For ( / ) = exp(− 2 / 2 ), where = 2 /√ , Proudman found the value = 13.5, whereas with Heisenberg's form for ( / ), as given by Neise and Koopmann, = 37.5 [21], 0 is the density, 0 is the speed of sound, is turbulent length scales, and is turbulent velocity defined as…”

Section: Broadband Noise Sources Modelmentioning

confidence: 98%

“…Carolus et al investigated two prediction methods for broadband noise of low-pressure axial fans [20]. Neise and Koopmann investigated experimentally a method by which an acoustic resonator can be used to reduce at source the aerodynamic noise generated by turbo machinery [21]. Velarde-Suárez et al carried out an experimental study about the aerodynamic tonal noise sources in a centrifugal fan with backward curved blades [22].…”

Section: Introductionmentioning

confidence: 99%

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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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Section: Broadband Noise Sources Modelmentioning

confidence: 98%

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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“…However, the main problem with a Helmholtz resonator is the discrepancy between measured and calculated results, noticed by, e.g. Alster [1], Dickey and Selamet [6], Ingard [16], Lambert [24], Neise [32], Selamet et al [36], Singh et al [38] and Tang and Sirignano [40].…”

Section: Introductionmentioning

confidence: 98%

Resonant frequency of an adjustable Helmholtz resonator in a hydraulic system

Kela

2008

Arch Appl Mech

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An adjustable Helmholtz resonator in hydraulics is studied because of obvious lack of studies in the field. First the theory of a Helmholtz resonator is reviewed by examining older studies on the subject. Most of the previous studies have covered Helmholtz resonators in acoustics, but the same basic theory can be applied to hydraulics. After the theory review the test equipment and measurement methods are presented and some results are calculated analytically using the classical model and a modified model that takes the effect of spring mass into consideration. The spring mass is taken into account because the density of hydraulic oil is over 700 times greater than the density of air. In the last section the results of the calculations and measurements are discussed, and it is noted that the results of the experiments agree better with the modified model of classical Helmholtz theory. Some explanations for residual discrepancies are given but also some remarks are presented.

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“…clearance is an important factor for reducing the blade passing frequency. In 1980, Neise and Koopmann [6,7] installed a quarter-wavelength acoustic resonator on the cut-o! region for reducing blade-passing noise.…”

Section: Introductionmentioning

confidence: 99%

Application of Feedforward Adaptive Active-Noise Control for Reducing Blade Passing Noise in Centrifugal Fans

Bai

2001

Journal of Sound and Vibration

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Reduction of centrifugal fan noise by use of resonators

Cited by 45 publications

References 9 publications

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

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

Resonant frequency of an adjustable Helmholtz resonator in a hydraulic system

Application of Feedforward Adaptive Active-Noise Control for Reducing Blade Passing Noise in Centrifugal Fans

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