Cylinder wake influence on the tonal noise and aerodynamic characteristics of a NACA0018 airfoil

Takagi, Yuya; Fujisawa, Nobuyuki; Nakano, Tamaki; Nashimoto, Atsushi

doi:10.1016/j.jsv.2006.04.012

Cited by 23 publications

(9 citation statements)

References 20 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The occurrence of multiple equispaced peaks following a ladder structure has been observed experimentally in several studies, among them Arbey & Bataille (1983), Nakano et al (2006), Takagi et al (2006), Arcondoulis et al (2009) and Chong & Joseph (2012). In numerical studies, the same multiple-peak structure of the far-field pressure spectrum has been confirmed by Desquesnes et al (2007), Le Garrec et al (2008) and Jones & Sandberg (2011); the frequency-ladder structure induced by a varying free-stream velocity, on the other hand, has not been investigated numerically as the calculations are computationally expensive.…”

Section: Introductionmentioning

confidence: 85%

A global analysis of tonal noise in flows around aerofoils

Pando

Schmid

Sipp³

2014

J. Fluid Mech.

View full text Add to dashboard Cite

International audienceThe generation of discrete acoustic tones in the compressible flow around an aerofoil is addressed in this work by means of nonlinear numerical simulations and global stability analyses. The nonlinear simulations confirm the appearance of discrete tones in the acoustic spectrum and, for the chosen flow case, the global stability analyses of the mean-flow dynamics reveal that the linearized operator is stable. However, the flow response to incoming disturbances exhibits important transient growth effects that culminate in the onset of aeroacoustic feedback loops, involving instability processes on the suction- and pressure-surface boundary layers together with their cross-interaction by acoustic radiation at the trailing edge. The features of the aeroacoustic feedback loops and the appearance of discrete tones are then related to the features of the least-stable modes in the global spectrum: the spatial structure of the direct modes displays the coupled dynamics of hydrodynamic instabilities on the suction surface and in the near wake. Finally, different families of global modes will be identified and the dynamics that they represent will be discussed

show abstract

Section: Introductionmentioning

confidence: 85%

A global analysis of tonal noise in flows around aerofoils

Pando

Schmid

Sipp³

2014

J. Fluid Mech.

View full text Add to dashboard Cite

show abstract

“…Mean flow quantities, velocity spectra of the turbulent motions as well as pressure spectra in the far-field are available. In a similar manner, Takagi et al 24 investigated the influence of the cylinder transverse location (perpendicular to the freestream flow direction) on the turbulent development of the flow around the airfoil and showed that it may have an impact on the radiated acoustic field.…”

Section: Introductionmentioning

confidence: 99%

A parametric study of the noise radiated by the flow around multiple bodies: direct noise computation of the influence of the separating distance in rod-airfoil flow configurations

Berland

Lafon

Crouzet

et al. 2011

17th AIAA/CEAS Aeroacoustics Conference (32nd AIAA Aeroacoustics Conference)

View full text Add to dashboard Cite

The sound radiated by an airfoil in the wake of a rod is predicted by means of compressible large-eddy (LES) simulation. The LES strategy is based on high-order spectral-like numerical methods to allow the direct noise calculation of the sound sources. Owing to the complexity of the geometry, an overset grid approach is implemented in order to tackle with turbulent flows around multiple solid bodies. First, the aerodynamic data as well as the acoustic far-field are thoroughly compared to the experimental data of Jacob et al. [J. Theoret. Comput. Fluid Dyn., 19(3), 2005] in order to demonstrate the accuracy of the present simulation. Then a parametric study of the influence of separating rod-airfoil distance on the flow regimes and on the acoustic radiation is performed.

show abstract

“…Although these studies on flow field around the fan blade allow for the understanding of flow phenomena, such as separation, reattachment and vortex shedding, these techniques are not suitable for identifying the noise source distribution. For such a problem, cross-correlation analysis of noise signal and velocity fluctuation provides an effective measure for visualizing the noise source distribution , which is originally developed for the detection of discrete frequency noise source from a symmetrical airfoil (Takagi et al, 2006;Nakano et al, 2007;. In this technique, flow structure regarding noise generation is detected by cross-correlation analysis, and the generation mechanism of aerodynamic noise is examined through the flow structure related to the noise generation.…”

Section: Regular Papermentioning

confidence: 99%

Visualization of aerodynamic noise source around a rotating fan blade

Nashimoto

Fujisawa

Nakano

et al. 2008

J Vis

Self Cite

View full text Add to dashboard Cite

The purpose of this study is to understand the aerodynamic noise source distribution around a rotating fan blade by measuring the noise signal and velocity field around the blade. The local noise-level distribution over the fan blade is measured by microphone arrays, and the flow field is visualized by smoke and phase-averaged PIV measurement. The noise source distribution is examined by cross-correlation analysis between noise signal and velocity fluctuation. It is found that the noise source is located near the rotating fan blade, especially around leading and trailing edges. The separation and reattachment of flow are observed near the leading edge, and the tip vortices and vortex shedding are found near the trailing edge. The cross-correlation distribution of the noise signal and the radial velocity fluctuation shows large magnitude in the correlated regions, which indicates the noise generation by the formation of vortex structure around the blade.

show abstract

Cylinder wake influence on the tonal noise and aerodynamic characteristics of a NACA0018 airfoil

Cited by 23 publications

References 20 publications

A global analysis of tonal noise in flows around aerofoils

A global analysis of tonal noise in flows around aerofoils

A parametric study of the noise radiated by the flow around multiple bodies: direct noise computation of the influence of the separating distance in rod-airfoil flow configurations

Visualization of aerodynamic noise source around a rotating fan blade

Contact Info

Product

Resources

About