Investigation of orifice aeroacoustics by means of multi-port methods

Sack, Stefan; Åbom, Mats

doi:10.1016/j.jsv.2017.06.026

Cited by 12 publications

(7 citation statements)

References 27 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The increase in power decreases with frequency and also when the distance separation is larger. These results are in line with those published in [16] in the case of two diaphragms inserted in a circular duct (see Fig. 14 in [16]) where it is shown that the increase in power becomes marginal when the distance exceeds at least 10 times the hydraulic diameter.…”

Section: Case Of Two Diaphragms In Tandemsupporting

confidence: 93%

“…These results are in line with those published in [16] in the case of two diaphragms inserted in a circular duct (see Fig. 14 in [16]) where it is shown that the increase in power becomes marginal when the distance exceeds at least 10 times the hydraulic diameter. Second, a series of consecutive and clearly distinguishable peaks at low frequencies below the first cut-off frequency.…”

Section: Case Of Two Diaphragms In Tandemsupporting

confidence: 93%

“…The academic study consists of two identical diaphragms with rectangular openings inserted in a duct of rectangular cross-section and separated by three different distances which are comparable with the transverse dimensions of the duct. It is interesting to note that similar configurations, mainly conducted with circular geometries both for the duct and the orifice, have been the subject of many papers in the recent years and we can cite the work of Sovardi et al [12], Karban and Schram [13,14], Sack et al [15,16], and also [17]. In a somewhat more industrial context, other research work investigated the ability of different CFD software to predict broadband noise and the presence of tonal noise, see [18][19][20] for instance.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Experimental and numerical observation of flow-acoustics feedback phenomena due to two diaphragms in tandem inserted in a rectangular duct

de Reboul,

Perrey-Debain,

Ville

et al. 2024

Acta Acust.

View full text Add to dashboard Cite

The proximity of obstacles in a ventilation network can result in a significant increase of the noise production. In this paper, a tandem diaphragm inserted in a rigid duct with rectangular cross section is investigated and compared to a single diaphragm obstruction. The disturbed flow which reaches the second obstacle causes an amplification of the radiated noise which goes beyond a simple doubling of the power. Experimental results, carried with various spacing between the two diaphragms and bulk velocity, allows identifying other aeroacoustic source mechanisms which does not appear with a single diaphragm. Depending on the configuration, the broadband level can increase by more than 10 dB and feedback phenomena can appear at low frequency. Explanations and illustrations of those phenomena are given thanks to compressible-fluid simulations.

show abstract

Section: Case Of Two Diaphragms In Tandemsupporting

confidence: 93%

Section: Case Of Two Diaphragms In Tandemsupporting

confidence: 93%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Experimental and numerical observation of flow-acoustics feedback phenomena due to two diaphragms in tandem inserted in a rectangular duct

de Reboul,

Perrey-Debain,

Ville

et al. 2024

Acta Acust.

View full text Add to dashboard Cite

show abstract

“…The measured data are produced by a multiport technique. 18 Inlet (upstream) and outlet (downstream) power spectra are shown in Figure 5. The red symbols stand for analytical wake interaction broadband noise predictions only, because this mechanism is recognized as dominant.…”

Section: Basic Mode-matching Proceduresmentioning

confidence: 99%

Advanced noise modeling for future propulsion systems

Moreau

Roger

2018

International Journal of Aeroacoustics

View full text Add to dashboard Cite

In order to meet noise specifications for future foreseen aircraft propulsion systems, such as for ultrahigh bypass ratio turbofans and contra-rotating open rotors, the dominant turbomachinery noise mechanisms need to be modeled accurately at an early design stage. Two novel methods are presented here, which could significantly improve the existing analytical noise models. For the high-solidity ultrahigh bypass ratio, a mode-matching technique based on a modal expansion of acoustic and vortical variables in each subdomain of a blade row is shown to accurately reproduce sound generation and propagation in two-dimensional bifurcated channels and in three-dimensional annular unstaggered flat-plate cascades. For the low solidity contra-rotating open rotors, several extensions to Amiet's compressible isolated airfoil theory are coupled with Curle's and Ffowcs Williams and Hawkings' acoustic analogy in the frequency domain within a strip theory framework, to yield both far-field tonal and broadband noise. Including sweep in both tonal and broadband noise models is shown to significantly improve the comparison with experiments on a stationary swept airfoil in a uniform turbulent stream and on a realistic contrarotating open rotor geometry at approach conditions.

show abstract

“…The modal decomposition approach has been proved to be capable of characterizing a sample beyond the plane wave regime [10][11][12][13][14]. One advantage of this method over the spatial Fourier-transform method is its non-intrusiveness since it is sufficient to measure the pressure just at the boundaries to fully determine the system.…”

Section: Introductionmentioning

confidence: 99%