Experimental simulation of turbulent boundary layer induced vibrations by using a synthetic array

Abstract

Of particular interest is the experimental feasibility of replacing wind tunnel measurements with a substitute experiment to simulate Turbulent Boundary Layer (TBL) induced vibrations. This paper describes the development of an experimental procedure to address this issue. The proposed approach is based on the concept of uncorrelated wall pressure plane waves, which is introduced as a prelude to this study. Concretely, an array of acoustic monopoles can be used to generate these wall pressure plane waves. To this end, the design parameters of the array are studied numerically. However, when dealing with experimental applications, the number of monopoles required being prohibitive, the principle of synthetic array is applied instead. This technique allows simulating the effect of an array of acoustic monopoles from sequential measurements. To assess the validity of the proposed approach, the whole procedure is applied to simulate TBL induced vibrations of a thin elastic plate. The results obtained are in good agreement with those

Use of beamforming for detecting an acoustic source inside a cylindrical shell filled with a heavy fluid

“…In this case, 9 78 is the unit matrix : ; . More complex models can be found in the literature; for instance, different formulations for the cross-spectrum matrix J Bg have been developed for plane structures excited by a turbulent boundary layer [18], [19].…”

Experimental vibroacoustic testing of plane panels using synthesized random pressure fields

“…These studies aim at replacing costly and complex in-flight or wind-tunnel tests, or at improving existing tests in coupled anechoic-reverberant rooms. [2][3][4][5][6][7][8] Compared with the reproduction of a DAF that implies only reproducing acoustic components, the specific case of a subsonic TBL means reproducing acoustic and convective components, the latter having smaller spatial scales than the acoustic scale. A dense and nearfield array of reproduction sources is needed for the reproduction of such subwavelength scales, which is highly limiting in practice.…”

“…A dense and nearfield array of reproduction sources is needed for the reproduction of such subwavelength scales, which is highly limiting in practice. Handling such an array can be made possible by using wave number filtering properties of a test panel, 4,6 which leads to a reduction of the number of needed reproduction sources but requires an a priori knowledge of the panel properties. Another interesting possibility is the use of the synthetic array principle, proposed by Aucejo 6 and investigated here.…”

“…The first proposed method is a least squares approach (see Bravo 4 and Aucejo 6 for random pressure fields, or Kirkeby 9 for acoustic plane waves), while the two other methods are based on sound field reproduction techniques: the Wave Field Synthesis 5,10 (WFS) and the Planar Nearfield Acoustic Holography (P-NAH). 7,11 The main objective of this paper is to confirm the simulation results obtained with the last two proposed methods, to verify their experimental feasibility using a synthetic array as suggested in Refs.…”

“…7 and 8 and compare the obtained results with others publications. 4,6 Another objective is to develop an experimental method, which allows quantifying the differences in terms of Transmission Loss (TL) between DAF and TBL excitations. It is known that the acoustic excitation has a larger transmission efficiency than the convective excitation, and that the magnitude of the acoustic components of a subsonic TBL is 15 to 30 dB lower than the magnitude of the convective components.…”