Combined flow visualization and conjugated numerical heat transfer analysis were carried out to study the axial evolution of the buoyancy induced secondary vortex and reverse flow in a mixed convective air flow through a bottom heated, slightly inclined rectangular duct. Results were obtained for the Grashof number Gr ranging from 1.6 × 103 to 2.8 × 105, inclined angle φ from −20 deg to 26 deg and the Reynolds number Re below 102 covering the steady and time dependent flows. For the buoyancy-opposing case, at a certain critical buoyancy-to-inertia ratio depending on the Re and φ both the experimental and numerical results clearly showed the generation of the longitudinal vortex rolls in the entry half of the duct and a slender reverse flow zone was induced near the exit end of the duct. At a higher buoyancy-to-inertia ratio the stronger reverse flow moves upstream and is in a time periodic snaking motion which is considered to result from the Kelvin-Helmholtz instability associated with the two counter flow streams, namely, the downstream moving longitudinal vortex rolls and the upstream moving reverse flow. Through the viscous shearing effects the strong snaking reverse flow induces a number of eddies moving along it and the longitudinal rolls are pushed towards the duct sides. This strong interaction between the vortex flow and reverse flow leads to an earlier transition to turbulence. A correlation equation was proposed for the penetration length of the reverse flow. However, for buoyancy-assisting flow no reverse flow is induced and the longitudinal vortex rolls prevail for the buoyancy-to-inertia ratio up to 2.8 × 105. Significant conjugated heat transfer effects were noted from the numerical results.
Skip Nav Destination
Article navigation
Research Papers
Observation and Computation of Vortex and/or Reverse Flow Development in Mixed Convection of Air in a Slightly Inclined Rectangular Duct
W. L Lin,
W. L Lin
Department of Mechanical Engineering, National Chiao Tung University, 1001 Ta Hsueh Road, Hsinchu, Taiwan, R.O.C.
Search for other works by this author on:
T. F. Lin
T. F. Lin
Department of Mechanical Engineering, National Chiao Tung University, 1001 Ta Hsueh Road, Hsinchu, Taiwan, R.O.C.
Search for other works by this author on:
W. L Lin
Department of Mechanical Engineering, National Chiao Tung University, 1001 Ta Hsueh Road, Hsinchu, Taiwan, R.O.C.
T. F. Lin
Department of Mechanical Engineering, National Chiao Tung University, 1001 Ta Hsueh Road, Hsinchu, Taiwan, R.O.C.
J. Heat Transfer. Nov 1997, 119(4): 691-699 (9 pages)
Published Online: November 1, 1997
Article history
Received:
June 26, 1996
Revised:
June 11, 1997
Online:
December 5, 2007
Citation
Lin, W. L., and Lin, T. F. (November 1, 1997). "Observation and Computation of Vortex and/or Reverse Flow Development in Mixed Convection of Air in a Slightly Inclined Rectangular Duct." ASME. J. Heat Transfer. November 1997; 119(4): 691–699. https://doi.org/10.1115/1.2824173
Download citation file:
Get Email Alerts
Cited By
Related Articles
Buoyancy Effects on Forced Convection Heat Transfer in the Transition Regime of a Horizontal Boundary Layer Heated From Below
J. Heat Transfer (August,1988)
Reversed Flow Structure and Heat Transfer Measurements for Buoyancy-Assisted Convection in a Heated Vertical Duct
J. Heat Transfer (November,1992)
Stabilization of Buoyancy-Driven Unstable Vortex Flow in Mixed
Convection of Air in a Rectangular Duct by Tapering Its Top Plate
J. Heat Transfer (February,2000)
A Time-Dependent Analysis of the Vortex Instability in the Thermal Entrance Region of an Inclined Parallel-Plate Channel
J. Heat Transfer (August,1992)
Related Proceedings Papers
Related Chapters
Crack(s) in a Rod or a Plate by Energy Rate Analysis
The Stress Analysis of Cracks Handbook, Third Edition
Cavitating Structures at Inception in Turbulent Shear Flow
Proceedings of the 10th International Symposium on Cavitation (CAV2018)
Natural and Mixed Convection
Thermal Management of Microelectronic Equipment