Trailing edge noise estimation by tomographic Particle Image Velocimetry

Pröbsting, Stefan; Tuinstra, Marthijn; Scarano, Fulvio

doi:10.1016/j.jsv.2015.02.018

Cited by 30 publications

(42 citation statements)

References 39 publications

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“…For the former, values of v ′ RMS also cover a smaller y r extent before dropping to zero. Translating the above observations in terms of noise generation by the trailing edge requires the evaluation of the intensity and spectrum of the hydrodynamic surface pressure fluctuations that are scattered by it (see Pröbsting et al 2015a;Bull 1979;Brooks and Hodgson 1981). In the present experiments, the measured amplitude of wall-normal RMS fluctuations and their closeness to the sharp edge is used to infer a trend in the expected sound level that is produced.…”

Section: Turbulence Statisticsmentioning

confidence: 96%

Flow topology and acoustic emissions of trailing edge serrations at incidence

et al. 2016

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Section: Turbulence Statisticsmentioning

confidence: 96%

Flow topology and acoustic emissions of trailing edge serrations at incidence

et al. 2016

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“…29,30 Wall-pressure fluctuations due to a convecting incompressible turbulent flow can be estimated by solving the Poisson equation. 31,32 The latter is obtained by combining the Navier-Stokes momentum equations with the one for continuity 33,34 and relates pressure fluctuations to a source term, which is a function of the velocity field.…”

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confidence: 99%

Three-dimensional flow field over a trailing-edge serration and implications on broadband noise

2016

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The three-dimensional flow field over the suction side of a NACA 0018 airfoil with trailing-edge serrations was studied by means of time-resolved tomographic particle image velocimetry. Mean flow results show that the boundary layer thickness decreases along the streamwise direction with a corresponding reduction of the size of the turbulent structures developing over the suction side of the serrations. At a positive angle of attack, streamwise-oriented and counter-rotating vortices aligned with the edge of the serrations are found to be the main features of the mean flow field. Their formation is attributed to the pressure imbalance between the two sides of the airfoil and the mixing layer at the edge. They locally modify the effective angle seen by the turbulent flow approaching the serrated edge. This effect may contribute to the serration underperformance in terms of noise reduction reported in literature. The spatial distribution of the spectra of the source term of the Poisson equation, which relates the velocity field to pressure fluctuations, suggests that the contribution of the serrations to far-field broadband noise is a function of the streamwise location. This observation is congruent with the spectra of the wall-normal and spanwise velocity fluctuations, which typically show low intensity close to the tips of the individual serrations. It follows that analytical models must take into account the local contribution to the far-field noise induced by the streamwise variation of the hydrodynamic pressure on the serration surface.

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“…A similar procedure for comparison between model equations and beamforming results was described by. 10 The raw and corrected sound pressure level values are shown in Fig. 9 for the chord based Reynolds number of 600, 000 case.…”

Section: B Acoustic Emissionmentioning

confidence: 99%

“…Amiet 6 and Howe 7 assumed that the incident pressure fluctuations on the surface below the turbulent boundary convect over the trailing edge, acting as an impedance discontinuity, where the fluctuations are scattered in the form of acoustic waves. This theory forms the basis of multiple experimental and numerical studies, such as the Large Eddy Simulation study of Christophe, 8 the surface pressure measurements of Brooks and Hodgson, 9 and the recent study of Pröbsting et al 10 with high-speed tomographic Particle Image Velocimetry based pressure reconstruction.…”

Section: Introductionmentioning

confidence: 99%

Numerical and experimental investigation of a beveled trailing edge flow and noise field

Velden

Pröbsting

Jong

et al. 2015

21st AIAA/CEAS Aeroacoustics Conference

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Efficient tools and methodology for the prediction of trailing edge noise experience substantial interest within the wind turbine industry. In recent years, the Lattice Boltzmann method has received increased attention for providing an efficient alternative for the numerical solution of complex flow problems. Based on the fully explicit, transient, compressible Lattice Boltzmann solution in combination with the Ffowcs Williams and Hawking analogy, an estimation of the acoustic emission in the far field is obtained. To validate this methodology for the prediction of trailing edge noise, the flow around a plate with an asymmetric 25 degree beveled trailing edge in low Mach number flow is analyzed. Flow field dynamics are compared to experimental data obtained from Particle Image Velocimetry measurements and show similar trends and behavior for both the mean and fluctuating velocity. Results of the acoustic prediction are compared to acoustic measurements obtained through phased array beamforming in combination with a source power integration technique. Vortex shedding is captured, broadband noise is present on both the experimental and numerical obtained noise spectra and a typical cardioid-like directivity behavior is found.

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Trailing edge noise estimation by tomographic Particle Image Velocimetry

Cited by 30 publications

References 39 publications

Flow topology and acoustic emissions of trailing edge serrations at incidence

Flow topology and acoustic emissions of trailing edge serrations at incidence

Three-dimensional flow field over a trailing-edge serration and implications on broadband noise

Numerical and experimental investigation of a beveled trailing edge flow and noise field

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