Numerical investigation of the flow dynamics past a three-element aerofoil
| Autor: | Romain Laraufie, Sébastien Deck |
|---|---|
| Rok vydání: | 2013 |
| Předmět: |
Length scale
Chord (aeronautics) Airfoil Physics 020301 aerospace & aeronautics Mechanical Engineering Geometry 02 engineering and technology Aerodynamics Condensed Matter Physics 01 natural sciences 010305 fluids & plasmas symbols.namesake 0203 mechanical engineering Mach number Mechanics of Materials 0103 physical sciences symbols Aeroacoustics Strouhal number Detached eddy simulation |
| Zdroj: | Journal of Fluid Mechanics. 732:401-444 |
| ISSN: | 1469-7645 0022-1120 |
| DOI: | 10.1017/jfm.2013.363 |
| Popis: | A numerical investigation of the flow dynamics around a two-dimensional high-lift configuration was carried out by means of a zonal detached eddy simulation (ZDES) technique for flow conditions corresponding to aircraft approach. Both slat and flap regions have been scrutinized and compared with experimental data available in the literature. It is shown that slat and flap coves behave like shallow cavities. The distance between the upstream cusp and the downstream edge is the relevant length scale for each cove taken separately. Consistently with previous findings, this study indicates that the maximum of the broadband spectrum of slat (respectively flap) pressure fluctuations occurs for Strouhal numbers $0. 5\leq \mathit{St}\leq 4$ when based on slat chord (respectively on flap chord) and free-stream velocity. It is shown that mode $(n)$ of the slat cove and mode $(n+ 1)$ of the flap cove are very close making a coherent phase relationship possible. A large-scale coupled self-sustained oscillations mechanism between slat and flap cavities, evidenced by spectral analysis, occurs at a Strouhal number $\mathit{St}= 3{\unicode{x2013}} 6$ based on the main wing chord and free-stream velocity. This yields to an acoustic feedback mechanism characterized by a normalized frequency depending on the free stream Mach number like $\mathit{St}= (1- { M}_{0}^{2} )/ 2{M}_{0} $. The present result appears to line up with the findings by Hein et al. (J. Fluid Mech., vol. 582, 2007, pp. 179–202) who showed that two types of resonance could exist: surface waves ones, scaling with the total aerofoil length and longitudinal cavity-type resonances, scaling with the slat cove length. |
| Databáze: | OpenAIRE |
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