Reduction of Airfoil Turbulence-Impingement Noise by Means of Leading-Edge Serrations and/or Porous Material

Roger, Michel; Schram, Christophe; Santana, Leandro D. de

doi:10.2514/6.2013-2108

Cited by 108 publications

(87 citation statements)

References 19 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In their paper they attribute the reductions in noise to a more rapid phase variation of pressure fluctuations along the serrated LE compared to the straight leading edge. This explanation of the noise reduction mechanism is consistent with the strip model proposed by Roger et al (2013). Clair et al (2013) have presented a numerical and experimental investigation into the effect of sinusoidal leading edge serrations for the reduction of turbulence-aerofoil interaction noise.…”

Section: Introductionsupporting

confidence: 64%

“…Roger et al (2013) have formulated an analytic model for the sound generation due to a turbulent flow interacting with a flat plate serrated leading edge of infinite chord. Their model treats the serrations as a continuously varying leading-edge sweep whose unsteady aerodynamic response is predicted by splitting the aerofoil into strips of small spanwise extent and assimilating the local curved edge to its tangent to make each strip a slice of a swept aerofoil, whose response functions are known.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Performance and mechanism of sinusoidal leading edge serrations for the reduction of turbulence–aerofoil interaction noise

et al. 2017

View full text Add to dashboard Cite

This paper presents the results of a detailed experimental investigation into the effectiveness of sinusoidal leading edge serrations on aerofoils for the reduction of the noise generated by the interaction with turbulent flow. A detailed parametric study is performed to investigate the sensitivity of the noise reductions to the serration amplitude and wavelength. The study is primarily performed on flat plates in an idealized turbulent flow, which we demonstrate captures the same behaviour as when identical serrations are introduced onto 3D aerofoils. The influence on the noise reduction of the turbulence integral length-scale is also studied. An optimum serration wavelength is identified whereby maximum noise reductions are obtained, corresponding to when the transverse integral length-scale is roughly one-forth the serration wavelength. This paper proves that, at the optimum serration wavelength, adjacent valley sources are excited incoherently. One of the most important findings of this paper is that, at the optimum serration wavelength, the sound power radiation from the serrated aerofoil varies inversely proportional to the Strouhal number St h = f h U , where f , h and U are frequency, serration amplitude and flow speed, respectively. A simple model is proposed to explain this behaviour. Noise reductions are observed to generally increase with increasing frequency until the frequency at which aerofoil self-noise dominates the interaction noise. Leading edge serrations are also shown to reduce trailing edge self-noise. The mechanism for this phenomenon is explored through PIV measurements. Finally, the lift and drag of the serrated aerofoil are obtained through direct measurement and compared against the straight edge baseline aerofoil. It is shown that aerodynamic performance is not substantially degraded by the introduction of the leading edge serrations on the aerofoil.

show abstract

Section: Introductionsupporting

confidence: 64%

Section: Introductionmentioning

confidence: 99%

Performance and mechanism of sinusoidal leading edge serrations for the reduction of turbulence–aerofoil interaction noise

et al. 2017

View full text Add to dashboard Cite

show abstract

“…Roger et al [59] studied the effect of tubercles, along with porous materials, on the NACA 0012 airfoil in reducing tonal noise. Experiments were carried out on TLE with A¼ 0.12%c and λ¼0.10% c, for a Re range 1.3 Â 10 5 -2 Â 10 5 .…”

Section: Influence Of Tle On Tonal Noise and Broadband Noisementioning

confidence: 99%

“…Van Nierop et al [22] hypothesised that tubercles can effectively reduce airfoil tonal noise. Implementing TLE reduces tonal and broadband noise on the airfoils [50][51][52][53][54][55][56][57][58][59][60][61][62][63][64][65][66].…”

Section: Influence Of Tle On Tonal Noise and Broadband Noisementioning

confidence: 99%

Mimicking the humpback whale: An aerodynamic perspective

Aftab

Razak

Rafie

et al. 2016

Progress in Aerospace Sciences

View full text Add to dashboard Cite

“…Roger et al [7] have also studied experimentally the sound generation due to the impingement of turbulent flow at the LE of a NACA-12 aerofoil and its reductions using sinusoidal LE serrations. They proposed a new analytical model for the noise reductions due to serrated leading edges by extending Amiet's theory [8].…”

Section: Introductionmentioning

confidence: 99%

Airfoil noise reductions through leading edge serrations

et al. 2015

View full text Add to dashboard Cite

This paper provides an experimental investigation into the use of leading edge serrations as a means of reducing the broadband noise generated due to the interaction between the aerofoil's leading edge (LE) and impinging turbulence. Experiments are performed on a flat plate in an open jet wind tunnel. Grids are used to generate isotropic homogeneous turbulence. The leading edge serrations are in the form of sinusoidal profiles of wavelengths, λ, and amplitudes, 2h. The frequency and amplitude characteristics are studied in detail in order to understand the effect of LE serrations on noise reduction characteristics and are compared with straight edge baseline flat plates. Noise reductions are found to be insignificant at low frequencies but significant in the mid frequency range (500 Hz to 8 kHz) for all the cases studied. The flat plate results are also compared to the noise reductions obtained on a serrated NACA-65 aerofoil with the same serration profile. Noise reductions are found to be significantly higher for the flat plates with a maximum noise reduction of around 9 dB compared with about 7 dB for the aerofoil. In general, it is observed that the sound power reduction level (∆PWL) is sensitive to the amplitude, 2h of the LE serrations but much less sensitive to the serration wavelength, λ. Thus, this paper sufficiently demonstrates that the LE amplitude act as a key parameter for enhancing the noise reduction levels in flat plates and aerofoils.

show abstract

Reduction of Airfoil Turbulence-Impingement Noise by Means of Leading-Edge Serrations and/or Porous Material

Cited by 108 publications

References 19 publications

Performance and mechanism of sinusoidal leading edge serrations for the reduction of turbulence–aerofoil interaction noise

Performance and mechanism of sinusoidal leading edge serrations for the reduction of turbulence–aerofoil interaction noise

Mimicking the humpback whale: An aerodynamic perspective

Airfoil noise reductions through leading edge serrations

Contact Info

Product

Resources

About