Flow Characteristics over Double Delta Wings at Low Reynolds Numbers
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Tarih
2020
Yazarlar
Dergi Başlığı
Dergi ISSN
Cilt Başlığı
Yayıncı
Asce-Amer Soc Civil Engineers
Erişim Hakkı
info:eu-repo/semantics/closedAccess
Özet
Within the scope of this study, a quantitative investigation was carried out employing the particle image velocimetry (PIV) technique to determine vortical flow characteristics of 70 degrees/40 degrees, 70 degrees/50 degrees, and 70 degrees/55 degrees double delta wings (DDWs). Experiments were performed in four chordwise sections (x/c=0.5, 0.6, 0.8, and 1) at two Reynolds numbers (R=1x104 and 2.5x104) and different angles of attack (alpha=5 degrees, 10 degrees, 15 degrees, and 25 degrees). It was observed that the secondary vortex is dominant on flow characteristics of double delta wings at low Reynolds numbers. The strengths of vortices increase with increases of both the wing sweep angle and Reynolds number. Furthermore, the location of wing vortex breakdown moves farther downstream as the wing sweep angle increased. Depending on the angle of attack, Reynolds number, and the wing sweep angle, either dual (strake and wing) or triple (strake, wing, and secondary) leading-edge vortices were observed. At a Reynolds number value R=1x104 and angles of attack in the range of alpha <= 15 degrees, the interactions of the vortices influence the flow structure significantly. Dominant frequencies of the vortices are detected near the shear layer formed between the strake vortex and secondary vortex, generally. Moreover, the spectral analyses indicated that bursting of the vortices causes complicated flow patterns over double delta wings, including small-scale vortices. It was found that the transverse Reynolds normal stress concentrates at chordwise sections where secondary vortices are dominant, whereas the locations of peak magnitude of vertical Reynolds normal stress coincide with the strake vortex cores.
Açıklama
Anahtar Kelimeler
Double delta wing (DDW), Vortical flow, Wing sweep angle, Particle image velocimetry (PIV)
Kaynak
Journal of Aerospace Engineering
WoS Q Değeri
Q2
Scopus Q Değeri
Q2
Cilt
33
Sayı
4
