Aerodynamic sound production in low speed flow ducts

Nelson, P.A.; Morfey, C. L.

doi:10.1016/0022-460x(81)90372-2

Cited by 126 publications

(71 citation statements)

References 10 publications

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“…9. The results are better than those measured by Nelson and Morfey, 16 as can be seen by the smaller errors at all frequencies ͑see Fig. 9͒.…”

Section: Acoustic Measurementsmentioning

confidence: 47%

“…Comparing the above expressions with those obtained by Nelson and Morfey 16 for the sound power generated by an in-duct spoiler, the interaction factor ␤ N can be defined as follows:…”

Section: Theory and Predictive Equations Of Noise Produced By In-mentioning

confidence: 95%

“…where ⌸ S can be obtained by using the prediction method provided by Nelson and Morfey, 16 and ␤ N can be determined by experiments.…”

Section: Theory and Predictive Equations Of Noise Produced By In-mentioning

confidence: 99%

“…16 Oldham and Ukpoho 17 then rewrote the Nelson-Morfey equations. They determined the appropriate values of the open area ratio and of the characteristic dimension to be applied to a flow spoiler in a circular or a square duct.…”

Section: Introductionmentioning

confidence: 99%

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Flow noise from spoilers in ducts

Mak

Jia

et al. 2009

The Journal of the Acoustical Society of America

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Measurements of flow noise produced by strip spoilers in the air duct of a ventilation system and radiated from an open exhaust termination unit into a reverberation chamber have been made. The results agree with the previous work of Nelson and Morfey ͓J. Sound Vib. 79, 263-289 ͑1981͔͒. Prediction of flow noise produced by multiple spoilers requires the values of the ratio of the mean drag forces that act on the spoilers, the phase relationship between the fluctuating drag forces that act on the spoilers, and the coherence function of the noise sources. The latter is empirically derived from the measured results, where the predicted results agree well with the experimental results within 3 dB at most frequencies except for very high frequencies.

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“…9. The results are better than those measured by Nelson and Morfey, 16 as can be seen by the smaller errors at all frequencies ͑see Fig. 9͒.…”

Section: Acoustic Measurementsmentioning

confidence: 47%

“…Comparing the above expressions with those obtained by Nelson and Morfey 16 for the sound power generated by an in-duct spoiler, the interaction factor ␤ N can be defined as follows:…”

Section: Theory and Predictive Equations Of Noise Produced By In-mentioning

confidence: 95%

“…where ⌸ S can be obtained by using the prediction method provided by Nelson and Morfey, 16 and ␤ N can be determined by experiments.…”

Section: Theory and Predictive Equations Of Noise Produced By In-mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Flow noise from spoilers in ducts

Mak

Jia

et al. 2009

The Journal of the Acoustical Society of America

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“…This effect can be modeled by extracting the state of the fluid flow and feeding it into the acoustic element. There the additional flow noise is calculated by (semi)empirical models, as given in [3,10] for instance. An example of a complex compound pipe component with flow noise is given in Fig.…”

Section: Flow-acoustic Interactionmentioning

confidence: 99%

SoundDuctFlow: A Modelica Library for Modeling Acoustics and Flow in Duct Networks

Kühnelt

Bauml

Haumer

2009

Linköping Electronic Conference Proceedings

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SoundDuctFlow, a Modelica library for the joint calculation of acoustic and flow quantities in HVAC (Heating, Ventilation and Air Conditioning) ducts is presented. Modeling the sound propagation in ducts by one dimensional acoustic twoport methods is a well-established technique for the acoustic characterization of large HVAC duct networks. Two different approaches of acoustic modeling will be considered in the framework: When resonant phenomena are insignificant, it is often sufficient to apply band-averaged models to predict the sound power level and the transmission loss within the individual components of the duct network. For the low frequency range where linear plane wave propagation is valid, acoustic two and multi-port models based on a transmission matrix formulation of the sound pressure can be applied for high frequency resolution and phase accurate calculations. For the prediction of the mean air flow in the duct network pressure loss models are applied. The coupling of acoustic and flow elements permits the simulation of flow acoustic phenomena. For setting up large networks a smooth work flow is vital for the user: The simulation is easily set up using the GUI provided by Dymola. External parameterisation ensures persistent data management. The resulting system of equations is automatically pre-processed and solved by Dymola. In this paper an overview of this new library is given together with exemplary applications.

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Experimental Characterization of Centrifugal Pumps as an Acoustic Source at the Blade-Passing Frequency

Rzentkowski

Zbroja

2000

Journal of Fluids and Structures

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Aerodynamic sound production in low speed flow ducts

Cited by 126 publications

References 10 publications

Flow noise from spoilers in ducts

Flow noise from spoilers in ducts

SoundDuctFlow: A Modelica Library for Modeling Acoustics and Flow in Duct Networks

Experimental Characterization of Centrifugal Pumps as an Acoustic Source at the Blade-Passing Frequency

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