Measurement of flow noise generation and pressure loss of nets and screens

Geyer, Thomas; Poppe, W.; Sarradj, Ennes

doi:10.1016/j.apacoust.2018.01.008

Cited by 8 publications

(3 citation statements)

References 7 publications

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“…It is worth noting that, although the self-noise levels are within close proximity of the background noise level, the grid with highest solidity ratio (C1) seems to generate highest levels of self noise. These observations corroborate the link between the blockage created by the grid and generated self-noise reported by Geyer et al [30].…”

Section: B Far-field Noise Resultssupporting

confidence: 92%

“…The pressure drop across the grid is linked to the geometric property of , which is a factor in the self-noise generated by the grids the presented results in Fig. 12, consistent with the results in Geyer et al [30].…”

Section: B Far-field Noise Resultssupporting

confidence: 89%

“…Geyer et al [18] however, employed the use of a microphone beamforming array to measure the interaction noise, but concluded that turbulence generation for aeroacoustic facilities deserved further study [18]. In an effort to further understand the noise generated by grids and screens, Geyer et al [30], conducted a study using a plethora of grids, nets and screens mounted at the contraction nozzle outlet. The study assessed the pressure drop across the screen and related it to the grid self-noise, resulting in a basic prediction tool for the frequency-dependent noise generated by nets or screens.…”

Section: Introductionmentioning

confidence: 99%

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Grid Generated Turbulence for Aeroacoustic Facility

et al. 2022

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This paper provides an insight into the grid generated turbulence for aeroacoustic studies. Several passive grids of square bars were tested in the open-jet aeroacoustic facility at the University of Bristol. The geometric properties of the grids and their position within the tunnel contraction nozzle were varied to quantify their influence on the average and statistical flow properties, as well as the generated self-noise. Moreover, case studies involving turbulence interaction noise generation with a NACA0012 airfoil and cylinder were conducted. Turbulence intensity, integral length scale, and the anisotropy of the flow generated by each grid were characterized by hot-wire measurements, and the associated far-field noise was measured by a

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Section: B Far-field Noise Resultssupporting

confidence: 92%

Section: B Far-field Noise Resultssupporting

confidence: 89%

Section: Introductionmentioning

confidence: 99%

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Grid Generated Turbulence for Aeroacoustic Facility

et al. 2022

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Flow and acoustic characterization of turbulence grids at wind tunnel nozzle exit

Li,

Zhu,

Maryami

et al. 2024

Journal of Sound and Vibration

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A thorough experimental investigation on airfoil turbulence interaction noise

2023

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This paper on aerofoil turbulence interaction noise reveals the nature of the relation between the distortion type of turbulent structures and radiated far-field noise. The turbulence interaction phenomenon is explored through comprehensive simultaneous hot-wire, surface pressure and far-field noise measurements. Two grid turbulence cases are utilized to examine the effect of the coherent structure's length scale compared to the aerofoil's leading-edge radius. The results show that the turbulent structures with a size comparable to the leading-edge radius disperse into smaller three-dimensional structures, losing their spatial coherence in the vicinity of the stagnation point. In contrast, the structures with larger integral length scales distort into highly-coherent two-dimensional structures, yielding an increase in the surface pressure fluctuation energy spectra and the chordwise extent of the affected area by the interaction phenomenon, which is found to be responsible for the increased levels of far-field noise. The turbulence characteristics of the flow far upstream of the stagnation point determine the unsteady loading behaviour at the stagnation point yet have little influence on the unsteady loading of the full aerofoil chord. The stagnation point velocity fluctuations manifest a strong link to the remainder of the aerofoil chord, as well as the near-field hydrodynamic to far-field acoustic signal coherence, whilst demonstrating no communication with the surface pressure fluctuations at the stagnation point.

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Measurement of flow noise generation and pressure loss of nets and screens

Cited by 8 publications

References 7 publications

Grid Generated Turbulence for Aeroacoustic Facility

Grid Generated Turbulence for Aeroacoustic Facility

Flow and acoustic characterization of turbulence grids at wind tunnel nozzle exit

A thorough experimental investigation on airfoil turbulence interaction noise

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