Prediction of high frequency gust response with airfoil thickness effects

Lysak, Peter D.; Capone, Dean E.; Jonson, Michael L.

doi:10.1016/j.jfluidstructs.2013.02.006

Cited by 26 publications

(32 citation statements)

References 27 publications

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“…Semi-analytical models have been developed to predict turbulence-aerofoil interaction noise for realistic aerofoils, that includes the effects of thickness Gershfeld (2004); Roger (2010); Glegg and Devenport (2010); Moriarty et al (2005); Lysak et al (2013); Billson (2002). This work will be discussed in section 2.1 and compared against careful measured noise data.…”

Section: Analytical and Experimental Studiesmentioning

confidence: 99%

“…2.6. Gershfeld's correction can be rewritten in terms of an attenuation coefficient as: Lysak et al (2013);Lysak (2011) developed an empirical expression for β(t) based on timedomain calculations, accounting for the gust distortion by the mean flow around the aerofoil. In the study, Lysak considered NACA 65 aerofoils of different thickness to chord ratio in the range of 4% to 20%.…”

Section: Comparison Of Thickness-based Empirical Models For the Predimentioning

confidence: 99%

“…By fitting the numerical predicted noise data Lysak et al (2013) obtained second order polynomial fit is given by: Moriarty et al (2005) developed an empirical relation for the noise reduction using a boundary element method. His correction expressed as a β factor is of the form:…”

Section: Comparison Of Thickness-based Empirical Models For the Predimentioning

confidence: 99%

“…A time-domain analytical method based on the vortex lift theory of Howe (2001) has been developed by Lysak et al (2013);Lysak (2011), to capture the effects of aerofoil thickness on the high frequency aerofoil response to an impinging vortical gust. This approach can account for gust distortion by the mean flow around the aerofoil leading edge.…”

Section: Introductionmentioning

confidence: 99%

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Aerofoil geometry effects on turbulence interaction noise

Paruchuri

2015

21st AIAA/CEAS Aeroacoustics Conference

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Faculty of Engineering and the Environment Institute of Sound and Vibration Research Doctor of PhilosophyAerofoil geometry effects on turbulence interaction noise by Chaitanya PARUCHURI Fan broadband is one of the dominant noise sources on an aircraft engine, particularly at approach. The dominant noise generation mechanism is due to turbulent-aerofoil interaction noise (TAI). This thesis investigates the effect of changes in 2D aerofoil geometry on TAI noise. The main focus of this thesis is to attempt to reduce it through the development of innovative leading edge geometries. The first two chapters of the thesis deals with an experimental and numerical investigation into the effect of aerofoil geometry on interaction noise on single aerofoils and on cascades. Consistent with previous work, they show that variations in aerofoil parameters, such as aerofoil thickness, leading edge nose radius and camber, produce only a small changes in broadband interaction noise at approach conditions. Subsequent chapters deal with the development of innovative leading edge serration profiles aimed at reducing interaction noise. Chapter 4 is a detailed study into the limitations of single-wavelength serrations in reducing interaction noise. The optimum profile is identified. Chapters 5, 6 and 7 all deal with the development of innovative profiles that can provide up to 10dB of additional noise reductions compared to single-wavelength serrations. For each of the profiles investigated a simple model is developed to aid the understanding of their interaction mechanism. v

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Section: Analytical and Experimental Studiesmentioning

confidence: 99%

Section: Comparison Of Thickness-based Empirical Models For the Predimentioning

confidence: 99%

Section: Comparison Of Thickness-based Empirical Models For the Predimentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Aerofoil geometry effects on turbulence interaction noise

Paruchuri

2015

21st AIAA/CEAS Aeroacoustics Conference

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“…The effects of aerofoil geometry on turbulence-aerofoil interaction noise has been studied extensively (Gershfeld 2004;Roger 2010;Moriarty et al 2005;Lysak et al 2013;Gill et al 2013;Devenport et al 2010;Evers & Peake 2002;Chaitanya et al 2015a). It has been demonstrated by the authors of the current paper Haeri et al 2014;Narayanan et al 2015;Chaitanya et al 2015b;Kim et al 2016) and others that introducing leading edge serrations can be an effective method of reducing far field noise.…”

Section: Introductionmentioning

confidence: 99%

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

et al. 2017

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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.

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Unsteady aerodynamics of a wing in a novel small-amplitude transverse gust generator

Fernandez¹,

Cleaver²,

Gursul³

2020

Exp Fluids

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A novel small-amplitude high-frequency gust generator has been developed that works by oscillating a small fence on the wind tunnel wall. The gust generator produces approximately constant local angle of attack in the chordwise direction. Due to the challenges of measuring small and slightly non-uniform gust angles the gust generator was calibrated using direct lift measurements on a symmetric wing set at zero geometric angle of attack. Unsteady lift force measurements and the Theodorsen's theory were used for the dynamic calibration of the gust angle. At nonzero geometric angles of attack, if the wing’s effective angle of attack remains below the stall angle, unsteady lift closely follows the static lift curve with very small hysteresis. Beyond the stall angle, dynamic stall and larger lift hysteresis are observed. Interestingly, in this regime, if flow is separated and a separation bubble is maintained on the wing throughout the cycle then increasing frequency reduces lift hysteresis. The slope of the lift curve, averaged over the cycle, may be greater than that of attached flow. The gust response is more sensitive to maximum effective angle of attack than the reduced frequency or the reduced pitch rate. The normalized lift change is much larger for separated flows than for attached flows. Graphic abstract

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Prediction of high frequency gust response with airfoil thickness effects

Cited by 26 publications

References 27 publications

Aerofoil geometry effects on turbulence interaction noise

Aerofoil geometry effects on turbulence interaction noise

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

Unsteady aerodynamics of a wing in a novel small-amplitude transverse gust generator

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