The Variation of Slat Noise with Mach and Reynolds Numbers

Lockard, David P.; Choudhari, Meelan M.

doi:10.2514/6.2011-2910

Cited by 16 publications

(8 citation statements)

References 25 publications

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“…The scaled horizontal coordinate uses the Strouhal number based on the slat chord and the freestream velocity. The vertical coordinate shows the power spectral density (PSD) levels adjusted to a fifth power of Mach the number [10]. Unscaled results are given for reference.…”

Section: Overall Sound Pressure Levelmentioning

confidence: 99%

“…Slat noise has been studied from wind-tunnel measurements [4][5][6][7], numerical simulations [8][9][10][11][12], and flyover tests [13]: in all of which the upper slat trailing-edge appears as a potential region for noise emission. A limited number of unswept and untapered high-lift scaled models has been studied in the literature, e.g., the MD30P30N [14][15][16], the Boeing 777 two-dimensional (2-D) high lift [17], and energy-efficient transport [18,19].…”

Section: Introductionmentioning

confidence: 99%

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Slat Noise from an MD30P30N Airfoil at Extreme Angles of Attack

et al. 2018

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This study investigates the slat noise of a two-dimensional scaled, unswept, and untapered MD30P30N high-lift model. The experimental data refer to aeroacoustic and aerodynamic measurements in a closed-section wind tunnel for a wide range of angles of attack (from −6 deg up to the stall; approximately at 18 deg) and Mach numbers between 0.07 and 0.1. Three slat configurations (the original MD30P30N, another with a higher slat deflection, and one with smaller slat gap and overlap) are studied experimentally. The signal processing applied to the acoustic data involves conventional beamforming enhanced by two deconvolution algorithms, namely, DAMAS and CLEAN-SC. An original variation of the beamforming cluster approach that is based on the coherence level among microphone pairs is introduced, and it improves the results obtained by DAMAS. Below −2 deg and above 12 deg angles of attack, the slat noise is very small and mostly below the wind-tunnel background noise for all configurations. Between −2 and 12 deg angles of attack, the slat noise spectra are substantially affected by the slat configuration, although it always contains a dominant low-frequency content, a midfrequency broadband noise, and a single high-frequency broad peak. Within this range, the lower angles of attack display the strongest low-frequency narrowband peaks. In fact, at lower angles of attack, the low-frequency narrowband peaks scale with a Mach power above 10.

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Section: Overall Sound Pressure Levelmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Slat Noise from an MD30P30N Airfoil at Extreme Angles of Attack

et al. 2018

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“…26 Subsequent measurements 27,28 and computations [29][30][31][32][33][34][35][36] at NASA Langley Research Center targeted the unsteady aspects of the flow field associated with the 30P30N configuration. Two different wind tunnel entries in NASA's Basic Aerodynamic Research Tunnel (BART) provided particle image velocimetry (PIV) measurements of the unsteady flow field within the slat cove region, along with steady pressure measurements on the entire airfoil.…”

Section: Physical Configurationmentioning

confidence: 99%

Assessment of Slat Noise Predictions for 30P30N High-Lift Configuration from BANC-III Workshop

Choudhari

Lockard

2015

21st AIAA/CEAS Aeroacoustics Conference

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This paper presents a summary of the computational predictions and measurement data contributed to Category 7 of the 3 rd AIAA Workshop on Benchmark Problems for Airframe Noise Computations (BANC-III), which was held in Atlanta, GA, on June 14-15, 2014. Category 7 represents the first slat-noise configuration to be investigated under the BANC series of workshops, namely, the 30P30N two-dimensional high-lift model (with a slat contour that was slightly modified to enable unsteady pressure measurements) at an angle of attack that is relevant to approach conditions. Originally developed for a CFD challenge workshop to assess computational fluid dynamics techniques for steady high-lift predictions, the 30P30N configurations has provided a valuable opportunity for the airframe noise community to collectively assess and advance the computational and experimental techniques for slat noise. The contributed solutions are compared with each other as well as with the initial measurements that became available just prior to the BANC-III Workshop. Specific features of a number of computational solutions on the finer grids compare reasonably well with the initial measurements from FSU and JAXA facilities and/or with each other. However, no single solution (or a subset of solutions) could be identified as clearly superior to the remaining solutions. Grid sensitivity studies presented by multiple BANC-III participants demonstrated a relatively consistent trend of reduced surface pressure fluctuations, higher levels of turbulent kinetic energy in the flow, and lower levels of both narrow band peaks and the broadband component of unsteady pressure spectra in the nearfield and farfield. The lessons learned from the BANC-III contributions have been used to identify improvements to the problem statement for future Category-7 investigations. Nomenclature a = speed of sound b sim = spanwise extent of simulation domain b = model span c = chord length of stowed configuration = 0.4572 m (18 inches) c s = slat chord C d = computed overall drag coefficient (scaled by planform area c⋅b sim ) C L = computed overall lift coefficient (scaled by planform area c⋅b sim ) C L, RMS= computed RMS lift coefficient (scaled by planform area c⋅b sim ) C L,s = contribution to overall lift coefficient (scaled by planform area c⋅b sim ) from slat C L,m = contribution to overall lift coefficient (scaled by planform area c⋅b sim ) from main wing C L,f = contribution to overall lift coefficient (scaled by planform area c⋅b sim ) from flap 1 Aerospace Technologist, Computational AeroSciences Branch, M.S. 128. Associate Fellow, AIAA. 2 Aerospace Technologist, Computational AeroSciences Branch, M.S. 128. Senior Member, AIAA. 3 Team members are listed in Table 1. Downloaded by PURDUE UNIVERSITY on July 26, 2015 | http://arc.aiaa.org | 2 Cp = surface pressure coefficient = (p-p ∞ )/(ρ ∞ U ∞ 2)/2 d impingement = distance between shear layer impingement location and slat trailing edge, normalized by c K = coverage factor for confidence interval L xy = minimum distanc...

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“…Slat noise has been studied from wind tunnel measurements 5,6,7,8,9 , numerical simulations 10,11,12,13,14,15 , and flyover tests 16 . Wind tunnel experiments using scaled high-lift models have revealed a slat noise signature featuring from broadband to tonal noise components.…”

Section: Introductionmentioning

confidence: 99%

Experiments on Slat Noise from -6° to 18° Angles of Attack

Amaral

Pagani

Himeno

et al. 2016

46th AIAA Fluid Dynamics Conference

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This study focuses on investigating the slat noise of a two-dimensional scaled, unswept and untapered, MD30P30N high-lift model. The database refers aeroacoustic and aerodynamic measurements in a closed-section wind tunnel for a wide range of angles of attack, namely from −6 • and 18 • , and Mach number ranging from 0.07 to 0.1. Aeroacoustic measurements were carried using a wall-mounted microphone array. The signal processing applied to the acoustic data involved conventional beamforming enhanced by two deconvolution algorithms, DAMAS and CLEAN-SC. Suction-based wall boundary-layer control was applied to provide a more two dimensional flow over the model span. Chord-wise and span-wise static pressure measurements were performed. Slat noise spectra revel low-frequency tones, broadband noise and a single broad tone in the higher frequency range. The results show all slat noise components are strongly affected by wing angle of attack. The low-frequency tones vanish at lower negative wing angles of attack but reach their higher level at lower positive angles of attack. The tones level variation within a narrow range of angles of attack may be over 10 dB/Hz. Overall, the dominant part in the slat noise spectra reduces as the wing angle of attack increases, rendering higher frequency noise components potential contributors to the overall noise.

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The Variation of Slat Noise with Mach and Reynolds Numbers

Cited by 16 publications

References 25 publications

Slat Noise from an MD30P30N Airfoil at Extreme Angles of Attack

Slat Noise from an MD30P30N Airfoil at Extreme Angles of Attack

Assessment of Slat Noise Predictions for 30P30N High-Lift Configuration from BANC-III Workshop

Experiments on Slat Noise from -6° to 18° Angles of Attack

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