Boundary Layer Noise in Aeroacoustic Wind Tunnels

Duell, Edward; Walter, Joel; Arnette, Steve; Yen, Joseph

doi:10.2514/6.2004-1028

Cited by 12 publications

(5 citation statements)

References 6 publications

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“…The result is shown in Figure 4 (b). Scaling is seen to range between about n = 5 and n = 7, which is consistent with the findings of Duell et al 13 A minimum is evident at about f ′ = 13, 000, but this seems to be due to the imperfect alignment of the particular local maxima in the spectral density. The scaling with Mach number aligns most, but not all of the features in the spectra.…”

Section: Iib Increase In Tunnel Noise Level With Mach Numbersupporting

confidence: 90%

“…or 10 log 10 p 2 ∝ n10 log 10 (M ) , where p 2 is the variance of the acoustic pressure, M is the tunnel Mach number and n is an exponent that we wish to determine. Such an analysis was performed on a one-third octave band basis by Duell et al, 13 and values of n between 5 and 7 were found, depending on frequency.…”

Section: Iib Increase In Tunnel Noise Level With Mach Numbermentioning

confidence: 99%

“…The spectral features of the measured noise are seen to be largely aligned with this normalization, although some irregularities are apparent. Based on their prior experience with large scale acoustic wind tunnels, 13 the consultants from Jacobs Engineering Group advised NASA that the major contributor to the noise spectra at Mach 0.20 above 2 kHz (as seen in Figure 3) was likely due to airflow over the perforated plate of the tunnel walls. This corresponds to the portion of the normalized sound spectra with f ′ > 13, 000, as seen in Figure 4 (a).…”

Section: Iib Increase In Tunnel Noise Level With Mach Numbermentioning

confidence: 99%

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The Acoustic Environment of the NASA Glenn 9- by 15-Foot Low-Speed Wind Tunnel

Stephens

2015

21st AIAA/CEAS Aeroacoustics Conference

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The 9-by 15-Foot Low Speed Wind Tunnel is an acoustic testing facility with a long history of aircraft propulsion noise research. Due to interest in renovating the facility to support future testing of advanced quiet engine designs, a study was conducted to document the background noise level in the facility and investigate the sources of contaminating noise. The anechoic quality of the facility was also investigated using an interrupted noise method. The present report discusses these aspects of the noise environment in this facility.

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Section: Iib Increase In Tunnel Noise Level With Mach Numbersupporting

confidence: 90%

Section: Iib Increase In Tunnel Noise Level With Mach Numbermentioning

confidence: 99%

Section: Iib Increase In Tunnel Noise Level With Mach Numbermentioning

confidence: 99%

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The Acoustic Environment of the NASA Glenn 9- by 15-Foot Low-Speed Wind Tunnel

Stephens

2015

21st AIAA/CEAS Aeroacoustics Conference

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“…The fast Fourier transform was performed on the sound pressure time course to obtain the sound pressure level spectra under each working condition, which were then sliding averaged [30][31][32]. The finite adjacent values of the experimental data with and without the model were respectively averaged to suppress the influence of random errors on the experimental results, as shown in Figure 15.…”

Section: Frequency Domain Analysismentioning

confidence: 99%

Numerical Simulation Study of Aerodynamic Noise in High-Rise Buildings

2022

Applied Sciences

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In order to study the aerodynamic noise on the surfaces of high-rise buildings under the action of strong winds, this paper numerically simulated the sound pressure field on the surface of a high-rise building using the large-eddy simulation method combined with the acoustic analog method of FW-H (Ffowcs Williams–Hawkings) equation and obtained the intensity radiation distribution of sound pressure on the surface of the building to further identify the area with the maximum sound pressure intensity of the noise radiation and thus achieve the purpose of locating noise source. The accuracy of the numerical simulation results for aerodynamic noise obtained in this paper was then verified by comparing with the acoustic wind tunnel experimental results. The locations of noise source obtained by numerical simulation and acoustic wind tunnel experiment were in good agreement. The sound pressure intensity pulsation time course was measured by the acoustic wind tunnel experiment, and the noise sound pressure level spectrum of each part of the building surface was obtained by fast Fourier transform (FFT). Furthermore, the spectral characteristics of the noise sound pressure level were analyzed. The results of the sound pressure level spectrum of aerodynamic noise obtained from the numerical simulation were compared with the acoustic wind tunnel experimental results, which were found to be very similar. The analysis of the sound pressure level spectrum of aerodynamic noise on the building surface reveals that the numerical simulation results in the middle- and high-frequency bands of the spectrum are in good agreement with the acoustic wind tunnel experimental results, but there is a difference between those in the low-frequency bands and the acoustic wind tunnel experimental results. The microphone array used to locate the noise source in the acoustic wind tunnel was found to suffer non-eliminable measurement errors, which might be a potential reason for a reasonably slight difference between the experimental and numerical simulation results. The background noise in the low-frequency band of the acoustic wind tunnel sound pressure level spectrum was relatively large, while there was basically no background noise in the numerical simulation. This paper shows that the numerical simulation method combined with large-eddy simulation and acoustic analogy (FW-H) can calculate the aerodynamic noise intensity at various points on the surfaces of high-rise buildings and reasonably predict the location of sound source. In addition, the numerical simulation results are similar to the acoustic wind tunnel experimental results in most frequency bands.

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“…The blade passage frequency (BPF = R • N blades ) and its harmonics appear as discrete tones in the test section background noise spectra at a fixed tunnel speed and may contaminate sensor measurements and affect flow physics. A spectrogram (contour plots of sensor signal power vs. frequency) obtained via short-time discrete Fourier transforms as the tunnel speed is increased is an effective tool to reveal blade passage contamination (Duell et al, 2004). Such contamination can be reduced via acoustic treatment of the tunnel circuit and other acoustic paths (in open-circuit case) between the fan and test section.…”

Section: Drive System Selectionmentioning

confidence: 99%

Fundamentals of Wind‐Tunnel Design

Cattafesta

Bahr

Mathew

2010

Encyclopedia of Aerospace Engineering

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Wind tunnels offer an effective tool to rapidly obtain data associated with flow over scaled or full‐scale models. Given their ubiquitous nature and utility, a wind‐tunnel design project is a fairly common yet complex exercise. We therefore review in this article the fundamentals of low‐speed wind‐tunnel design. The research goals and the specific measurement requirements are discussed, as well as the various space, budget, and power constraints that guide the tunnel design. Design guidelines are provided for the most common wind‐tunnel components, including flow conditioners, contraction, test section, diffuser, drive, and other optional components. Finally, facility characterization procedures are briefly summarized, including flow uniformity, turbulence intensity, and background noise and vibration levels.

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Boundary Layer Noise in Aeroacoustic Wind Tunnels

Cited by 12 publications

References 6 publications

The Acoustic Environment of the NASA Glenn 9- by 15-Foot Low-Speed Wind Tunnel

The Acoustic Environment of the NASA Glenn 9- by 15-Foot Low-Speed Wind Tunnel

Numerical Simulation Study of Aerodynamic Noise in High-Rise Buildings

Fundamentals of Wind‐Tunnel Design

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