On a three-dimensional investigation of airfoil turbulence-impingement noise and its reduction by leading-edge tubercles

Bampanis, Georgios; Roger, Michel; Moreau, Stéphane

doi:10.1016/j.jsv.2021.116635

Cited by 12 publications

(11 citation statements)

References 23 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The acoustic measurements presented in this paper were performed in the low-speed open-jet anechoic wind tunnel of Ecole Centrale de Lyon (ECL), which has been described in detail elsewhere [17,18]. A rectangular nozzle with a vertical exit cross-section of 15 cm x 30 cm delivers a clean uniform flow with turbulence intensity of 0.3% [19], at velocities ranging between 19 m/s to 32 m/s, into an anechoic chamber of 4 m x 5 m x 6 m. The contraction ratio of the nozzle is 2:1 from an initial section of 30 cm x 30 cm. A cambered airfoil NACA 6512-10 with a chord of = 13 cm is Simple SDOF cavity liners were used in this instance so that well-established models could be used to predict the liner acoustic impedance.…”

Section: A Wind-tunnel Set-up Airfoil and Over-tip Linermentioning

confidence: 99%

“…12a and 12b for the pressure side and the suction side respectively. The trends of the noise increase with the gap size vary across the spectrum but can be broadly divided into three groups: f=[2-6] kHz, f= [6][7][8][9][10][11][12] kHz and f= [12][13][14][15][16][17][18][19][20] kHz, which apply both in the pressure side and the suction side of the airfoil. The integrated spectrum for each frequency range and gap size is shown in Fig.…”

Section: Noise Localisation and Extractionmentioning

confidence: 99%

“…The second frequency range (f= [6][7][8][9][10][11][12] kHz), for which gap noise is dominant, does not present any saturation at the higher gap sizes but a monotonic increase of additional noise. In contrast, the noise sources at higher frequencies (f= [12][13][14][15][16][17][18][19][20] kHz) are quite insensitive to the gap size. The trends outlined above agree with the quantification of additional noise from the GAPB shown in Fig.…”

Section: Noise Localisation and Extractionmentioning

confidence: 99%

See 2 more Smart Citations

Aeroacoustic Assessment of Performance of Overtip Liners in Reducing Airfoil Noise

et al. 2021

Self Cite

View full text Add to dashboard Cite

The reduction of fan broadband noise in the next generation of Ultra-High By-pass-Ratio (UHBR) engines remains a key technology challenge for the foreseeable future. The Over-Tip-Rotor (OTR) liner concept has been studied as a technology with the potential to further reduce fan noise and significant noise reductions have been measured. This paper describes a fundamental experimental evaluation that represents the Over-Tip-Rotor liner as a static airfoil with its tip located over a flat plate containing a flush-mounted lined insert and separated from the airfoil tip by a small gap. Differences in measured far-field sound spectra and in source power estimates derived from post-processed spiral array data have shown broadband gap noise reductions of 5-10 dB, even in the absence of a tip gap. Over-tip liners are found to suppress noise sources when located in the immediate vicinity, irrespective of the generation mechanism, mainly due to back-reaction effects on the source. An analytical prediction model for the over-tip liner noise reduction, based on a point source located over an infinite lined plane, is evaluated and compared with the experimental data. The model captures the back-reaction effects and provides qualitative agreement with the measured data, including the variation of noise reduction with increasing gap size.

show abstract

Section: A Wind-tunnel Set-up Airfoil and Over-tip Linermentioning

confidence: 99%

Section: Noise Localisation and Extractionmentioning

confidence: 99%

Section: Noise Localisation and Extractionmentioning

confidence: 99%

See 1 more Smart Citation

Aeroacoustic Assessment of Performance of Overtip Liners in Reducing Airfoil Noise

et al. 2021

Self Cite

View full text Add to dashboard Cite

show abstract

“…Serrations Serrations are wavy-shape inserts that can be installed at both edges of a wing or blade profile. The leading-edge serrations have been applied to isolated profiles and fan blades [5,6]. The oblique edge on a leading-edge serration hill creates a destructive interference of the scattered surface pressure [7,8], resulting in a noise reduction in targeted frequency ranges.…”

Section: A Reduction Of Noise At the Sourcementioning

confidence: 99%

Development of the SmartAnswer Demonstrator: a Didactic Wind Tunnel for Aeroacoustic Applications

Tamaro

Zamponi

Schram

2022

28th AIAA/CEAS Aeroacoustics 2022 Conference

View full text Add to dashboard Cite

A small didactic wind tunnel demonstrator has been designed and manufactured at the von Karman Institute for Fluid Dynamics to illustrate the physical principles at stake in flow-induced noise generation, offer an audible perception of the effectiveness of noise-mitigation strategies, and serve as a practical test bench for aeroacoustic education and research. Seven mitigation technologies are embedded in a single facility, which addresses the noise generation by an airfoil, noise propagation in a duct, and noise transmission through a flexible panel. A challenging objective of this facility was to offer a perceptible impression of various aeroacoustic noise mechanisms at low flow speeds and a live assessment of the effectiveness of the noisereduction technologies. Different approaches combining multiple microphones, advanced signal-processing techniques, and real-time audio feedback have been implemented to this end. The results establish that the demonstrator enables a clear perception of the effectiveness of the noise-mitigation technologies. The facility is also suitable for fast and inexpensive preliminary investigations of future noise-reduction concepts, taking advantage of rapid prototyping techniques.

show abstract

“…The acoustic performances of serrations have been widely investigated, mostly on single airfoil configurations. Sinusoidal serrations are the most commonly studied [5][6][7][8][9], but other shapes such as the superposition of two sine curves [10] and a sawtooth pattern with or without slits [11] were also considered. These concepts showed promising performances, provided that the parameters defining the leading edge shape (pattern wavelength, serration depth) are carefully chosen with regards to the characteristic length of the incident turbulence.…”

Section: Introductionmentioning

confidence: 99%

Turbulence interaction noise from a rectilinear cascade of airfoils and effects of porous material inclusions

Clair

Salze

Souchotte

et al. 2023

AIAA AVIATION 2023 Forum

View full text Add to dashboard Cite

The broadband noise radiated by turbulent fan wakes interacting with the outlet guide vanes is one of the major broadband noise components of turbofan engines. In this paper, this broadband turbulence interaction noise is studied experimentally in an anechoic wind tunnel on a simplified configuration consisting in a rectilinear cascade of airfoils impinged by a turbulent flow generated by a turbulence grid. The cascade is made of 7 loaded airfoils with an adjustable incidence angle and the upstream flow velocities investigated are up to a Mach number of 0.53. The noise radiated by the cascade is evaluated using a circular array of microphones located in free-field downstream of the cascade, and also using a linear array of microphones flush mounted in the duct upstream of the cascade. A concept of airfoil with inclusions of porous material has been designed based on previous work and manufactured to be tested on this rectilinear cascade configuration. The results of the measurements performed with this airfoil concept are compared to the results of the fully rigid reference airfoil.

show abstract

On a three-dimensional investigation of airfoil turbulence-impingement noise and its reduction by leading-edge tubercles

Cited by 12 publications

References 23 publications

Aeroacoustic Assessment of Performance of Overtip Liners in Reducing Airfoil Noise

Aeroacoustic Assessment of Performance of Overtip Liners in Reducing Airfoil Noise

Development of the SmartAnswer Demonstrator: a Didactic Wind Tunnel for Aeroacoustic Applications

Turbulence interaction noise from a rectilinear cascade of airfoils and effects of porous material inclusions

Contact Info

Product

Resources

About