Application of an acoustic analogy to PIV data from rectangular cavity flows |
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Authors: | Christian Haigermoser |
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Institution: | (1) Politecnico di Torino, DIASP, Corso Duca degli Abruzzi 24, 10129 Turin, Italy |
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Abstract: | The present paper describes a method to derive information about the acoustic emission of a flow using particle image velocimetry
(PIV) data. The advantage of the method is that it allows studying sound sources, the related flow phenomena and their acoustic
radiation into the far field, simultaneously. In a first step the time history of two-dimensional instantaneous pressure fields
is derived from planar PIV data. In a successive step the Curle’s acoustic analogy is applied to the pressure data to obtain
the acoustic radiation of the flow. The test cases studied here are two rectangular cavity flows at very low Mach number with
different aspect ratios L/H. The main sound source is located at the cavity trailing edge and it is due to the impingement of vortices shed in the shear
layer. It is shown that the flow emits sound with a main directivity in the upstream direction for the smaller aspect ratio
and the directivity is more uniform for the larger aspect ratio. In the latter case the acoustic pressure spectra has a broader
character due to the impact of the downstream recirculation zone onto the shear layer instabilities, destroying their regular
pattern and alternating the main sound source. |
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Keywords: | |
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