Momentum and heat transfer in a complex recirculating flow
Three-dimensional and turbulent recirculating flows in enclosed spaces occur in many engineering situations. Accurate measurements of momentum- and heat-transfer characteristics are needed for direct engineering-design applications and for developments of numerical-simulation codes of these flows. A facility to generate recirculating flows driven by buoyancy and/or shear forces in a rectangular cavity was constructed to model such flows. Also, a visualization technique, involving temperature-sensitive liquid-crystal microcapsules, was developed to visualize the temperature and velocity fields simultaneously in any flow plane. Two flow cases were studied: (1) natural convection driven by buoyancy in a bottom-heated cavity, with Gr = 2.4 10/sup 7/, and (2) mixed-convection driven by shear force from a moving lid and buoyancy, with Gr = 2.4 x 10/sup 7/ and Re = 3200. In the mixed-convection case, Gr/Re/sup 2/ = 2.3, indicating that buoyancy and shear forces acting on the flow are comparable. In addition to the flow/temperature visualizations, measurements were made of velocity, temperature, and surface heat flux. Overall heat-transfer measurements were conducted for a wide range of the mixed-convection parameter, Gr/Re/sup 2/, in the cavity. Smooth transitions were found from natural convection to forced convection. The mixed convection regime was found in 0.5 < Gr/Re/sup 2/ < 80, the upper found of 80 being larger than that of flat plate data (about 10). This was probably due to heat-transfer enhancement by the TGL vortices.
- Research Organization:
- Stanford Univ., CA (USA)
- OSTI ID:
- 7029708
- Country of Publication:
- United States
- Language:
- English
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