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.
Rod-Airfoil PIV Sound Acoustic Analogy Curle's Analogy Aeroacoustic analysis of a rod-airfoil flow by means of timeresolved PIV Left: Predicted wave fronts that are emanating from the airfoil Right: Predicted directivity pattern, green dots represent measurements Problem area The present paper investigates the feasibility of prediction of vortexstructure noise based on time resolved Particle Image Velocimetry (PIV). We consider the case of an airfoil immersed in the wake of a cylindrical rod.
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