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

Moore, Peter; Lorenzoni, Valerio; Scarano, Fulvio

doi:10.1007/s00348-010-0932-y

Cited by 30 publications

(22 citation statements)

References 21 publications

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“…The time history of the Lagrangian velocity derivative computed by single-step scheme (LO) and by the multistep scheme (MS) proposed Moore et al (2010) is illustrated in Fig. 10 (center).…”

Section: Lagrangian Approach: A-posteriori Analysismentioning

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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“…The time history of the Lagrangian velocity derivative computed by single-step scheme (LO) and by the multistep scheme (MS) proposed Moore et al (2010) is illustrated in Fig. 10 (center).…”

Section: Lagrangian Approach: A-posteriori Analysismentioning

confidence: 99%

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

2010

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“…The other approach is the evaluation of the cross-correlation between the fluctuating static pressure fluctuation and the sound pressure fluctuation emitted from a bluff body [11]. On the other hand, the method using time-resolved PIV provides the time-series data of instantaneous velocity field, which allows the evaluation of time-derivative of the vector product of vorticity and velocity in the flow field [12] and the evaluation of the pressure fluctuation on the cylinder surface [13]. This method using the time-resolved PIV is effective for evaluating the aerodynamic sound spectrum, although it is very expensive and requires too many PIV image data to analyze the time-series velocity data.…”

Section: Introductionmentioning

confidence: 99%

“…A variety of experimental methods for localizing the sound sources have been proposed in literature, such as the acoustic impedance method [7], microphone array method [8], cross-correlation method [9]- [11], and the method using time-resolved particle image velocimetry (PIV) [12] [13]. Among these experimental methods, the last two methods allow for localization of the aerodynamic sound sources because they can evaluate simultaneously the velocity field, which supports the understanding of the generation mechanism for aerodynamic sound.…”

Section: Introductionmentioning

confidence: 99%

Measurement of Aerodynamic Sound Source around a Circular Cylinder by Particle Image Velocimetry

Oguma

Yamagata²,

Fujisawa³

2014

JFCMV

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The purpose of this paper is to propose a sound localization method as an alternative of the time-resolved particle image velocimetry (PIV) system for detecting the aerodynamic sound source of a circular cylinder in a uniform flow. The sound source intensity of a circular cylinder in a uniform flow is evaluated by measuring the time-derivative of instantaneous velocity field in the flow field using a pair of planar PIV system. It allows the visualization of the sound source intensity distribution, which is the time-derivative of the vector product of vorticity and velocity. The experimental results indicate that the aerodynamic sound is generated from the separation point and the velocity fluctuation in the separating shear layer from the circular cylinder. These results agree qualitatively with the previous findings from experiment and numerical simulation, which supports the validity of the present experimental method for evaluating the sound source intensity distribution.

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“…The velocity material derivatives are computed directly, using the method proposed by Liu and Katz 34 and further developed by Moore et al 11 The method consists of the evaluation of the total derivative of the velocity by tracking a fluid parcel by means of a Lagrangian approach, under the assumption of Taylor's hypothesis of frozen turbulence. This is permitted, since the characteristic fluctuations of the flow are small with respect to the characteristic velocity of the mean recirculating flow in the cavity, and therefore the larger structures, which are primarily responsible for the total sound emission, convect without much deformation within the duration of our acquisition.…”

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confidence: 99%

A study on the application of two different acoustic analogies to experimental PIV data

2011

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The aim of the present study is to compare two different acoustic analogies applied to timeresolved particle image velocimetry (PIV) data for the prediction of the acoustic far-field generated by the flow over a rectangular cavity. We consider the model problem of sound radiating from an open, two-dimensional, shallow cavity with an aspect ratio of 2 at a Reynolds number of 3.0 Â 10 4 (based on the cavity length). The study is carried out by simultaneous high-speed two-dimensional PIV and sound measurements. The instantaneous flow field is obtained from the PIV measurements. The emitted sound is then calculated using Curle's analogy and Vortex Sound Theory. To our knowledge, Vortex Sound Theory is used here for the first time in combination with time-resolved PIV data. The acoustic analogies are derived through rather different pathways, and the mathematical schemes used to solve the equations are sensitive in a different way to factors such as data resolution, noise level, and complexity of the geometry. Both methods indicate that the trailing edge of the cavity is the main sound source. The predictions of the acoustic field obtained by applying the two methods are analyzed and compared with the measured sound. For the presented case, the results show that both analogies estimate the overall sound pressure level quite well and that they give very similar results, both in total intensity and in the spectral distribution of the emitted sound.

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

Cited by 30 publications

References 21 publications

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

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

Measurement of Aerodynamic Sound Source around a Circular Cylinder by Particle Image Velocimetry

A study on the application of two different acoustic analogies to experimental PIV data

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