Experimental Investigation on 3D Acoustic Receptivity of a Laminar Boundary Layer in the Presence of Surface Non-Uniformities

Würz, W.; Herr, S.; Wagner, Siegfried; Kachanov, Y. S.

doi:10.1007/978-3-663-10901-3_68

Cited by 3 publications

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“…Cullen & Horton (1999) studied the acoustic receptivity for a stationary localized three-dimensional roughness in a two-dimensional boundary layer, but no quantitative receptivity coefficients were evaluated. For the first time, these coefficients were obtained experimentally by Würz et al (1998) for a single acoustic frequency and compared with calculations in Würz et al (1999). The subsequent development of these studies is discussed in the present paper.…”

Section: Introductionmentioning

confidence: 89%

Three-dimensional acoustic-roughness receptivity of a boundary layer on an airfoil: experiment and direct numerical simulations

et al. 2003

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The paper is devoted to an experimental and numerical investigation of the problem of excitation of three-dimensional Tollmien–Schlichting (TS) waves in a boundary layer on an airfoil owing to scattering of an acoustic wave on localized microscopic surface non-uniformities. The experiments were performed at controlled disturbance conditions on a symmetric airfoil section at zero angle of attack. In each set of measurements, the acoustic wave had a fixed frequency fac, in the range of unstable TS-waves. The three-dimensional surface non-uniformity was positioned close to the neutral stability point at branch I for the two-dimensional perturbations. To avoid experimental difficulties in the distinction of the hot-wire signals measured at the same (acoustic) frequency but having a different physical nature, the surface roughness was simulated by a quasi-stationary surface non-uniformity (a vibrator) oscillating with a low frequency fv. This led to the generation of TS-wavetrains at combination frequencies f1,2=fac ∓ fv. The spatial behaviour of these wavetrains has been studied in detail for three different values of the acoustic frequency. The disturbances were decomposed into normal oblique TS-modes. The initial amplitudes and phases of these modes (i.e. at the position of the vibrator) were determined by means of an upstream extrapolation of the experimental data. The shape of the vibrator oscillations was measured by means of a laser triangulation device and mapped onto the Fourier space.

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Section: Introductionmentioning

confidence: 89%