Free-stream turbulence and concave curvature effects on heated, transitional boundary layers

Journal Article · Fri May 01 04:00:00 EDT 1992 · Journal of Heat Transfer (Transactions of the ASME (American Society of Mechanical Engineers), Series C); (United States)

DOI:https://doi.org/10.1115/1.2911281· OSTI ID:7272993

Kim, J ^[1]; Simon, T W; Russ, S G ^[2]

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1. Calspan Corp., Buffalo, NY (United States)
2. Univ. of Minnesota, Minneapolis (United States)

An experimental investigation of transition in concave-curved boundary layers at two free-stream turbulence levels (0.6 and 8.6 percent) was performed. For the lower free-stream turbulence intensity case, Goertler vortices were observed in both laminar and turbulent flows using liquid crystal visualization and spanwise velocity and temperature traverses. Transition is thought to occur via a vortex breakdown mode. The vortex locations were invariant with time but were nonuniform across the span in both the laminar and turbulent flows. The upwash regions between two vortices were more unstable than were the downwash regions, containing higher levels of u{prime} and u{prime}v{prime}, and lower skin friction coefficients and shape factors. Turbulent Prandtl numbers, measured using a triple-wire probe, were near unity for all post-transitional profiles, indicating no gross violation of Reynolds analogy. No streamwise vortices were observed in the higher turbulence intensity case. This may be due to the high eddy viscosity, which reduces the turbulent intensity case. This may be due to the high eddy viscosity, which reduces the turbulent intensity case. This may be due to the high eddy viscosity, which reduces the turbulent Goertler number to subcritical values, thus eliminating the vortices, or due to an unsteadiness of the vortex structure that could both be observed by the techniques used. Based upon these results, predictions that assume two-dimensional modeling of the flow over a concave wall with high free-stream turbulence levels, as on the pressure surface of a turbine blade, seem to be adequate-there is no time-average, three-dimensional structure to be resolved. High levels of free-stream turbulence superimposed on a free-stream velocity gradient (which occurs within curved channels) cause a cross-total pressure within this region can rise above the value measured at the inlet to the test section.

• OSTI ID: 7272993
• Journal Information: Journal of Heat Transfer (Transactions of the ASME (American Society of Mechanical Engineers), Series C); (United States), Journal Name: Journal of Heat Transfer (Transactions of the ASME (American Society of Mechanical Engineers), Series C); (United States) Vol. 114:2; ISSN 0022-1481; ISSN JHTRA
• Country of Publication: United States
• Language: English

Related Subjects

42 ENGINEERING
420400* -- Engineering-- Heat Transfer & Fluid Flow
BENCH-SCALE EXPERIMENTS
BOUNDARY LAYERS
FLOW VISUALIZATION
FLUID FLOW
LAMINAR FLOW
LAYERS
MATHEMATICAL MODELS
PRANDTL NUMBER
TURBULENT FLOW
VORTEX FLOW
VORTICES