Aeroacoustic Analysis of a Rod-Airfoil Flow by Means of Time-Resolved PIV

Lorenzoni, Valerio; Moore, PD; Scarano, Fulvio

doi:10.2514/6.2009-3298

Cited by 20 publications

(27 citation statements)

References 21 publications

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“…This will help considerably to understand the sound production mechanisms and to investigate possible ways to reducing it. A similar approach was applied previously by Lorenzoni (2008) on a rod-airfoil configuration. This gave promising result for this simple case.…”

Section: Discussionmentioning

confidence: 99%

High speed PIV applied to aerodynamic noise investigation

et al. 2010

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In this paper, we study the acoustic emissions of the flow over a rectangular cavity. Especially, we investigate the possibility of estimating the acoustic emission by analysis of PIV data. Such a possibility is appealing, since it would allow to directly relate the flow behavior to the aerodynamic noise production. This will help considerably in understanding the noise production mechanisms and to investigate the possible ways of reducing it. In this study, we consider an open cavity with an aspect ratio between its length and depth of 2 at a Reynolds number of 2.4 9 10 4 and 3.0 9 10 4 based on the cavity length. The study is carried out combining high speed two-dimensional PIV, wall pressure measurements and sound measurements. The pressure field is computed from the PIV data. Curle's analogy is applied to obtain the acoustic pressure field. The pressure measurements on the wall of the cavity and the sound measurements are then used to validate the results obtained from PIV and check the range of validity of this approach. This study demonstrated that the technique is able to quantify the acoustic emissions from the cavity and is promising especially for capturing the tonal components on the sound emission.

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Section: Discussionmentioning

confidence: 99%

High speed PIV applied to aerodynamic noise investigation

et al. 2010

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“…From the temporal evolution of the cross-correlation coefficient, the authors suggested that the source region was located by the leading edge of the airfoil. With a similar experimental approach, the far-field aeroacoustic of the rod-airfoil configuration was investigated by Lorenzoni et al (2009) who reported a favorable comparison for the tonal component between microphone measurements and predictions based on Curle's acoustic analogy (1955) applied to time-resolved planar PIV (TR PIV).…”

Section: Introductionmentioning

confidence: 99%

“…Except for computational approaches, no account has been made of the 3-D features in the flow due to intrinsic limitation of the planar two-and threecomponent PIV technique. In the investigation of the rod-airfoil flow, Lorenzoni et al (2009) stated that a noise prediction more accurate than that obtained assuming 2-D flow could be achieved if 3-D flow effects are taken into account. Also, in the same investigation, the low temporal resolution limited the accuracy of the evaluated instantaneous pressure, as well as of the pressure time rate of change, which is of prior importance for the evaluation of Curle's aeroacoustic analogy.…”

Section: Introductionmentioning

confidence: 99%

“…By this work, tomographic particle image velocimetry technique (Elsinga et al 2006;Schröder et al 2008), in thin-volume configuration, enabling to fully describe the velocity gradient tensor, is applied to study the 3-D flow pattern of a rod-airfoil system similar to that investigated by Lorenzoni et al (2009). To discuss the 3-D flow effects neglected in the work by Lorenzoni et al (2009), pressure and material acceleration on the measurement domain midplane are compared to those evaluated from planar PIV.…”

Section: Introductionmentioning

confidence: 99%

“…Aeroacoustic predictions of flows interacting with bodysurfaces (Haigermoser 2009;Koschatzky et al 2010;Lorenzoni et al 2009) is a recent field where the aforementioned methods are applied to time-resolved PIV to extract the body-surface pressure distribution which is used to predict the instantaneous far-field acoustic pressure by means of Curle's analogy (1955). Higher accuracy in the pressure evaluation from PIV would lead to more reliable PIV-based sound predictions to be used together with computational aeroacoustics CAA (Crighton 1993), sensors and microphone arrays (Brooks and Humphreys 2003).…”

Section: Introductionmentioning

confidence: 99%

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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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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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Aeroacoustic Analysis of a Rod-Airfoil Flow by Means of Time-Resolved PIV

Cited by 20 publications

References 21 publications

High speed PIV applied to aerodynamic noise investigation

High speed PIV applied to aerodynamic noise investigation

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

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

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