Digitale Medien
Springer
Experiments in fluids
21 (1996), S. 417-426
ISSN:
1432-1114
Quelle:
Springer Online Journal Archives 1860-2000
Thema:
Maschinenbau
Notizen:
Abstract An experimental study was made of the flow over a backward-facing step. Excitations were given to separated flow by means of a sinusoidally oscillating jet issuing from a thin slit near the separation line. The Reynolds number based on the step height (H) varied 13000 ⩽ Re H ⩽ 33000. Effect of local forcing on the flow structure was scrutinized by altering the forcing amplitude (0 ⩽ A 0 ⩽ 0.07) and forcing frequency (0 ⩽ St H ⩽ 5.0). Small localized forcing near the separation edge enhanced the shear-layer growth rate and produced a large roll-up vortex at the separation edge. A large vortex in the shear layer gave rise to a higher rate of entrainment, which lead to a reduction in reattachment length as compared to the unforced flow. The normalized minimum reattachment length (x r )min/x x0 was obtained at St θ ≅ 0.01. The most effective forcing frequency was found to be comparable to the shedding frequency of the separated shear layer.
Materialart:
Digitale Medien
URL:
http://dx.doi.org/10.1007/BF00189044
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