Accurate experimental two-port analysis of flow generated sound

Holmberg, Andreas; Åbom, Mats; Bodén, Hans

doi:10.1016/j.jsv.2011.07.041

Cited by 36 publications

(26 citation statements)

References 26 publications

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“…For flow ducts the flush mounted microphone methods consist of the two-microphone method [23,24], multi-microphone methods [25,26] or the full wave decomposition method [27]. In this paper, as was suggested in [28], the multi-microphone method is applied using microphones with intermediate distances that all fulfil the limits given by Åbom and Bodén [29], which are…”

Section: Measurement Methodsmentioning

confidence: 99%

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Aeroacoustics of rectangular T-junctions subject to combined grazing and bias flows – An experimental investigation

Holmberg

Karlsson

Åbom

2015

Journal of Sound and Vibration

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Section: Measurement Methodsmentioning

confidence: 99%

“…Using more microphones, errors can be suppressed using e.g. over-determination techniques, or, as was suggested in [28], a clever choice of microphone pair to use can be made for each frequency in order to decrease the error sensitivity of the wave decomposition equations. The latter is performed in this work.…”

Section: Measurement Methodsmentioning

confidence: 99%

Aeroacoustics of rectangular T-junctions subject to combined grazing and bias flows – An experimental investigation

Holmberg

Karlsson

Åbom

2015

Journal of Sound and Vibration

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“…However, this approach was proven not to yield the required accuracy. For this reason a different approach is adopted, in which the 4 microphones on either side of the two-port system are used to compute the flow Mach number, the viscous losses and the effective upstream and downstream propagation wave number k ± z [26]. The Mach number, obtained at both sides of the twoport system is averaged over all frequencies and the final value is used for the impedance eduction calculations.…”

Section: The Influence Of the Mach Numbermentioning

confidence: 99%

Indirect acoustic impedance eduction in presence of flow based on an analytical two-port formulation

Santana

Roeck

Desmet

2014

Mechanical Systems and Signal Processing

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In order to assess the performance of advanced acoustic absorbing materials the acoustic impedance should be determined with high accuracy, especially, in presence of a grazing flow. This paper presents an analytical methodology for the grazing flow acoustic impedance eduction, based on a two-port representation of an acoustic system. This procedure is dedicated to the frequency range below the cut-on frequency of the transversal duct modes and its major appeal refers to a reduced number of microphones and the experimental rig simplicity. The methodology is verified by comparison with acoustic finite element simulations. Experiments are performed on two liner configurations and the educed impedance is compared with reference results obtained with a different approach at another test rig, and shows good agreement. A sensitivity analysis on the influence of the input parameters is carried out showing the influence of the rigid-/impedance wall transition effects, flow Mach number, number of microphones and microphone positioning accuracy.

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“…Once is determined, the external sources are deactivated and the source vector of interest can be found. This procedure is described in detail by (Holmberg et al, 2011).…”

Section: ‫1ݔ‬ ‫2ݔ‬mentioning

confidence: 99%