Heat transfer and fluid dynamics of concave-surface curvature. Final report, 1 January 1986-31 December 1988

Technical Report · Thu Apr 21 04:00:00 EDT 1988

OSTI ID:5882695

Bradshaw, P; Johnston, J P; Moffat, R J

This project investigated the mechanisms responsible for the known increases in shear stress and convective heat transfer when a turbulent boundary layer flows over a concave wall compared to a similar flow over a flat wall. The effects of grid-generated Free-Stream Turbulence (FST level< or = 7.5% ) were also examined for flat and concave-wall TBL's. The work was conducted in a large scale boundary layer using low-speed water flow. Momentum thickness Re was = 1400. Surface heat-transfer rate was measured with a constant-temperature metal surface and by use of a liquid-crystal surface. Temperature profiles were obtained by miniature thermocouple probe down to y+ = 3 and all three velocity components by a 3-D, laser velocimeter down to y+ = 7. Heat transfer and wall shear stress were both found to be augmented by curvature and free-stream turbulence applied separately, but the combined effect of curvature and FST is not simply the sum of the individual effects. In the case of wall stress, the effects of curvature are much larger than FST effects once the flow develops downstream. The nature of the interaction is being investigated using a working hypothesis based on the ideas of active (Reynolds stress producing) and inactive can stimulate only a limited increase (order 25%) in wall friction coefficient. However, for the moderate levels of FST used in this study, no such saturation process exists to limit the increase in surface heat-transfer rate.

• Research Organization: Stanford Univ., CA (USA). Dept. of Mechanical Engineering
• OSTI ID: 5882695
• Report Number(s): AD-A-207811/1/XAB
• Country of Publication: United States
• Language: English

Related Subjects

42 ENGINEERING
420400* -- Engineering-- Heat Transfer &amp; Fluid Flow
AUGMENTATION
BOUNDARY LAYERS
CONFIGURATION
CONVECTION
CRYSTALS
CYLINDRICAL CONFIGURATION
DIMENSIONS
DOCUMENT TYPES
ELEMENTS
ENERGY TRANSFER
FLUID FLOW
FLUID MECHANICS
FLUIDS
FRICTION
HEAT TRANSFER
LAYERS
LIQUID CRYSTALS
LIQUIDS
MASS TRANSFER
MEASURING INSTRUMENTS
MECHANICS
METALS
MINIATURIZATION
MOMENTUM TRANSFER
PROBES
PROGRESS REPORT
SATURATION
SHEAR
SURFACES
THERMOCOUPLES
THICKNESS
TURBULENCE
TURBULENT FLOW
VELOCITY
WALLS