Trailing-edge serrations: improving theoretical noise reduction models

Ayton, Lorna J.; Szőke, Máté; Paruchuri, Chaitanya C.; Devenport, William J.; Alexander, William N.

doi:10.2514/6.2021-2111

Cited by 4 publications

(2 citation statements)

References 14 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The scheduled experiments at the SWT investigated the trailing edge noise (Amiet 1976;Brooks, Pope, and Marcolini 1989) generation of a NACA0012 airfoil (Ayton et al 2021). This study was a collaborative work between VT, University of Southampton (UK) and University of Cambridge (UK).…”

Section: Introductionmentioning

confidence: 99%

Development of Hybrid Laboratory Sessions During the COVID-19 Pandemic

Szőke¹

2022

Advances

View full text Add to dashboard Cite

This paper presents the hybrid delivery method of a laboratory experiment at the Stability Wind Tunnel of Virginia Tech to some 170 students during April 2020, which can be considered the early stages of the COVID-19 induced lockdown. The steps of converting the hands-on labs to hybrid labs are presented in detail. Namely, a videoconferencing tool was used to (i) stream the instrumentation used, (ii) provide live video feed, and (iii) to interact with the students. Labs began with a remote tour of the facility, whilst the presence of an expert-at-a-distance added key value to the labs as it enhanced students conceptual understanding via verbal interaction. The experiments were then performed by laboratory personnel while student's engagement was kept high via the teleconferencing session. At the end of the two-week laboratory campaign, the students provided feedback of the laboratory sessions via an open-ended and closed-ended survey. They highlighted the added value of expert-at-distance, the live video feed, and the ability of working with instructors. While their feedback was rather positive, students showed a strong preference toward hands-on laboratories. Overall, the methodologies presented here can be considered a relatively low-cost method to upgrade hands-on laboratories to hybrid or remote labs.

show abstract

Section: Introductionmentioning

confidence: 99%

Development of Hybrid Laboratory Sessions During the COVID-19 Pandemic

Szőke¹

2022

Advances

View full text Add to dashboard Cite

show abstract

“…Among other authors, Guérin et al [1] showed that a satisfactory agreement can be reached when those isotropic turbulence spectra are used to predict rotor-stator-interaction noise. Trailing edge noise is caused by the interaction of boundary layer turbulence with the trailing edge of an airfoil and the critical ingredient for its prediction is the wall surface pressure autospectrum near the trailing edge, as Ayton et al [2] have also recently discussed in their paper. In contrast to the transverse velocity spectrum associated with leading edge noise, no comparable consensus exists within the scientific community for modeling the wall surface pressure autospectrum associated with trailing edge noise.…”

Section: Introductionmentioning

confidence: 99%

On the Modeling of Wall Surface Pressure Spectra for Trailing Edge Noise Prediction

Kissner

Guérin

Thisse

et al. 2022

28th AIAA/CEAS Aeroacoustics 2022 Conference

View full text Add to dashboard Cite

Broadband noise is a significant source for open rotors and Ultra High Bypass Ratio fans. The analytical description of the leading edge noise component is typically linked to the upwash velocity autospectrum of the impinging turbulence, and the modeling of the trailing edge component due to the interaction of the boundary layer turbulence with the trailing edge relies on the surface pressure autospectrum near the trailing edge. But while there is some consensus on describing transverse velocity frequency spectra for leading edge noise, there are a plethora of different models of varying complexity to describe wall surface pressure autospectra. Choosing an appropriate model to apply in the framework of fast and robust acoustic prediction tools is therefore no easy task. This paper aims to apply different models for predicting the surface pressure spectrum near the trailing edge of an airfoil. Experimental data for two airfoils at realistic flight Mach and Reynolds numbers were studied and different RANSinformed empirical models as well as the Stalnov TNO model were investigated regarding their ability to capture experimental trends.

show abstract

The impact of non-frozen turbulence on the modelling of the noise from serrated trailing edges

Tian,

Lyu

2024

J. Fluid Mech.

View full text Add to dashboard Cite

Serrations are commonly employed to mitigate the turbulent boundary layer trailing-edge noise. However, significant discrepancies persist between model predictions and experimental observations. In this paper, we show that this results from the frozen turbulence assumption. A fully developed turbulent boundary layer over a flat plate is first simulated using the large-eddy simulation method, with the turbulence at the inlet generated using the digital filter method. The space–time correlations and spectral characteristics of wall pressure fluctuations are examined. The simulation results demonstrate that the coherence function decays in the streamwise direction, deviating from the constant value of unity assumed in the frozen turbulence assumption. By considering an exponential decay function, we relax the frozen turbulence assumption and develop a prediction model that accounts for the intrinsic non-frozen nature of turbulent boundary layers. To facilitate a direct comparison with frozen models, a correction coefficient is introduced to account for the influence of non-frozen turbulence. The comparison between the new and original models demonstrates that the new model predicts lower noise reductions, aligning more closely with the experimental observations. The physical mechanism underlying the overprediction of the noise model assuming frozen turbulence is discussed. The overprediction is due to the decoherence of the phase variation along the serrated trailing edge. Consequently, the ratio of the serration amplitude to the streamwise frequency-dependent correlation length is identified as a crucial parameter in determining the correct prediction of far-field noise.

show abstract

Trailing-edge serrations: improving theoretical noise reduction models

Cited by 4 publications

References 14 publications

Development of Hybrid Laboratory Sessions During the COVID-19 Pandemic

Development of Hybrid Laboratory Sessions During the COVID-19 Pandemic

On the Modeling of Wall Surface Pressure Spectra for Trailing Edge Noise Prediction

The impact of non-frozen turbulence on the modelling of the noise from serrated trailing edges

Contact Info

Product

Resources

About