Pressure-gradient turbulent boundary layers developing around a wing sectionShow others and affiliations
2017 (English)In: Flow Turbulence and Combustion, ISSN 1386-6184, E-ISSN 1573-1987, Vol. 99, no 3-4, p. 613-641Article in journal (Refereed) Published
Abstract [en]
A direct numerical simulation database of the flow around a NACA4412 wing section at R e (c) = 400,000 and 5(ay) angle of attack (Hosseini et al. Int. J. Heat Fluid Flow 61, 117-128, 2016), obtained with the spectral-element code Nek5000, is analyzed. The Clauser pressure-gradient parameter beta ranges from ae integral 0 and 85 on the suction side, and from 0 to - 0.25 on the pressure side of the wing. The maximum R e (oee integral) and R e (tau) values are around 2,800 and 373 on the suction side, respectively, whereas on the pressure side these values are 818 and 346. Comparisons between the suction side with zero-pressure-gradient turbulent boundary layer data show larger values of the shape factor and a lower skin friction, both connected with the fact that the adverse pressure gradient present on the suction side of the wing increases the wall-normal convection. The adverse-pressure-gradient boundary layer also exhibits a more prominent wake region, the development of an outer peak in the Reynolds-stress tensor components, and increased production and dissipation across the boundary layer. All these effects are connected with the fact that the large-scale motions of the flow become relatively more intense due to the adverse pressure gradient, as apparent from spanwise premultiplied power-spectral density maps. The emergence of an outer spectral peak is observed at beta values of around 4 for lambda (z) ae integral 0.65 delta (99), closer to the wall than the spectral outer peak observed in zero-pressure-gradient turbulent boundary layers at higher R e (oee integral) . The effect of the slight favorable pressure gradient present on the pressure side of the wing is opposite the one of the adverse pressure gradient, leading to less energetic outer-layer structures.
Place, publisher, year, edition, pages
Springer, 2017. Vol. 99, no 3-4, p. 613-641
Keywords [en]
Turbulent boundary layer, Pressure gradient, Wing section, Direct numerical simulation
National Category
Fluid Mechanics
Identifiers
URN: urn:nbn:se:kth:diva-220718DOI: 10.1007/s10494-017-9840-zISI: 000416838200005PubMedID: 30069159Scopus ID: 2-s2.0-85027373953OAI: oai:DiVA.org:kth-220718DiVA, id: diva2:1170421
Funder
Swedish Research CouncilKnut and Alice Wallenberg FoundationSwedish e‐Science Research Center
Note
QC 20180104
2018-01-032018-01-032025-02-09Bibliographically approved