A rod-airfoil experiment as a benchmark for broadband noise modeling

Jacob, Marc C.; Boudet, Jérôme; Casalino, Damiano; Michard, Marc

doi:10.1007/s00162-004-0108-6

Cited by 234 publications

(247 citation statements)

References 29 publications

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“…Acoustic waves propagate predominantly in directions normal to the flow axis, and slightly upstream. This indicated directivity pattern is qualitatively the same as that identified by Jacob et al (2005). …”

Section: Resultssupporting

confidence: 74%

“…The techniques developed are applied to a time-resolved rod-airfoil PIV experiment, which is a useful benchmark for turbulence structure interaction noise Jacob et al 2005) and has received quite some treatment including Jacob et al (2008), Siller et al (2005), and Casalino et al (2003). This benchmark is particularly tractable for aeroacoustic analysis, as the dominant acoustic source is the impingement of large 2-D vortex rolls on the airfoil leading edge, which are readily resolvable by the PIV measurement.…”

Section: Introductionmentioning

confidence: 99%

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Two techniques for PIV-based aeroacoustic prediction and their application to a rod-airfoil experiment

2010

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In this paper, we discuss techniques by which the aeroacoustic properties of the turbulent flow in a rod-airfoil benchmark experiment can be inferred from time-resolved PIV measurement. While acoustic measurements can be made directly using microphones, the proposed techniques provide a means to directly link acoustic waves with specific flow events, which is invaluable in devising noise mitigation strategies. The approaches are possible thanks to recent improvements in digital and camera technology that can provide time-resolved measurements in air flows, necessary for the determination of unsteady flow quantities related to aeroacoustic production. Both techniques are based on Curle's acoustic analogy, where one is based on Lagrangian determination of the required quantities, while the other requires all flow quantities to be converted into Fourier modes. Application of both techniques yields results that are in reasonable agreement with microphone noise measurements for the rod-airfoil experiment.

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Section: Resultssupporting

confidence: 74%

Section: Introductionmentioning

confidence: 99%

Two techniques for PIV-based aeroacoustic prediction and their application to a rod-airfoil experiment

2010

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“…4. Black solid line represents the present simulated result while dashed line with solid squares is the measured data of Jacob et al [38]. It is shown that the calculated sound pressure frequency spectra agree well with the experiment results.…”

Section: Validation Of the Methodssupporting

confidence: 75%

On aerodynamic noises radiated by the pantograph system of high-speed trains

Zhang

2013

Acta Mech Sin

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Pantograph system of high-speed trains become significant source of aerodynamic noise when travelling speed exceeds 300 km/h. In this paper, a hybrid method of non-linear acoustic solver (NLAS) and Ffowcs WilliamsHawkings (FW-H) acoustic analogy is used to predict the aerodynamic noise of pantograph system in this speed range. When the simulation method is validated by a benchmark problem of flows around a cylinder of finite span, we calculate the near flow field and far acoustic field surrounding the pantograph system. And then, the frequency spectra and acoustic attenuation with distance are analyzed, showing that the pantograph system noise is a typical broadband one with most acoustic power restricted in the medium-high frequency range from 200 Hz to 5 kHz. The aerodynamic noise of pantograph systems radiates outwards in the form of spherical waves in the far field. Analysis of the overall sound pressure level (OASPL) at different speeds exhibits that the acoustic power grows approximately as the 4th power of train speed. The comparison of noise reduction effects for four types of pantograph covers demonstrates that only case 1 can lessen the total noise by about 3 dB as baffles on both sides can shield sound wave in the spanwise direction. The covers produce additional aerodynamic noise themselves in the other three cases and lead to the rise of OASPLs.

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“…For the rod-airfoil benchmark configuration (Jacob et al 2004), Henning et al (2009) recently investigated the mechanism of sound generation by means of simultaneous planar PIV in the near-field and phased-microphone-array measurements in the far-field. Cross-correlation between the acoustic pressure and velocity or vorticity fluctuations (Henning et al 2008) was applied to characterize flow structures involved in noise production.…”

Section: Introductionmentioning

confidence: 99%

Lagrangian and Eulerian pressure field evaluation of rod-airfoil flow from time-resolved tomographic PIV

2010

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This work investigates the rod-airfoil air flow by time-resolved Tomographic Particle Image Velocimetry (TR-TOMO PIV) in thin-light volume configuration. Experiments are performed at the region close to the leading edge of a NACA0012 airfoil embedded in the von Kármán wake of a cylindrical rod. The 3D velocity field measured at 5 kHz is used to evaluate the instantaneous planar pressure field by integration of the pressure gradient field. The experimental data are treated with a discretized model based on multiple velocity measurements. The time separation used to evaluate the Lagrangian derivative along a fluid parcel trajectory has to be taken into account to reduce precision error. By comparing Lagrangian and Eulerian approaches, the latter is restricted to shorter time separations and is found not applicable to evaluate pressure gradient field if a relative precision error lower than 10% is required. Finally, the pressure evaluated from tomographic velocity measurements is compared to that obtained from simulated planar ones to discuss the effect of 3D flow phenomena on the accuracy of the proposed technique.

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A rod-airfoil experiment as a benchmark for broadband noise modeling

Cited by 234 publications

References 29 publications

Two techniques for PIV-based aeroacoustic prediction and their application to a rod-airfoil experiment

Two techniques for PIV-based aeroacoustic prediction and their application to a rod-airfoil experiment

On aerodynamic noises radiated by the pantograph system of high-speed trains

Lagrangian and Eulerian pressure field evaluation of rod-airfoil flow from time-resolved tomographic PIV

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