Abstract
The effects of moderate streamwise (longitudinal) curvature on the growth, development, mixing and turbulence transport in parallel, co-flowing, two-stream mixing (free-shear) layers have been experimentally investigated. Stabilizing and destabilizing configurations (in the Taylor-Görtler sense) with identical boundary and initial conditions have been studied and compared to a plane mixing layer. Flow visualization and three-component laser Doppler velocimetry (LDV) techniques have been applied to investigate these flows. It was found that destabilizing curvature enhances the streamwise growth rate of the shear layer. Turbulence production, three-dimensionality, and fine-scale mixing are enhanced by destabilizing curvature, as well.
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Abbreviations
- r :
-
Moment of momentum ratio, (UR)min/(UR)max outside shear layer
- R :
-
Local radius of streamline curvature, R c + Y
- R c :
-
Mean radius of curvature at mid-profile, R c = R cl + Y 0
- R cl :
-
Radius of arc that is centered on splitter plate trailing edge
- Re δ :
-
Reynolds number = ΔUδ/v
- U, V, W :
-
Mean velocities along x, y, and z directions
- U*:
-
Normalized mean velocity, [(UR) - (UR)min]/[Rc × ΔU]
- u′,v′,w′ :
-
Velocity fluctuations
- x,y,z :
-
Streamwise, normal and spanwise coordinates
- Y 0 :
-
Y shift, evaluated at mid-profile, ΔU/2
- ΔU :
-
Velocity scale, (U 0 R 0 - U i R i )/R c
- δ :
-
Slope thickness of the shear layer, based on straight line through the central portion of the layer
- η :
-
Normalized cross-stream coordinate for profiles, (y - Y 0 )/δ
- λ :
-
(1 + r)/(1 - r)
- v :
-
Kinematic viscosity
- θ :
-
Momentum thickness
- σ :
-
Spreading parameter
- σ 0 :
-
Spreading parameter for single-stream mixing layer
- Ωx :
-
Streamwise component of vorticity
- ()i,()0 :
-
Inner or outer stream’s irrotational region
- (UR)min :
-
UR in irrotational region of lower speed stream
- (UR) max :
-
UR in irrotational region of higher speed stream
- < >:
-
Time averaged quantity
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Plesniak, M.W., Johnston, J.P. (1991). Reynolds Stress Evolution in Curved Two-Stream Turbulent Mixing Layers. In: Durst, F., Launder, B.E., Reynolds, W.C., Schmidt, F.W., Whitelaw, J.H. (eds) Turbulent Shear Flows 7. Springer, Berlin, Heidelberg. https://doi.org/10.1007/978-3-642-76087-7_18
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DOI: https://doi.org/10.1007/978-3-642-76087-7_18
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