Annals of the Assembly for International Heat Transfer Conference 13

ISBN 1-56700-225-0 / CD 1-56700-226-9

Year 2006

M. Yang
University of Shanghai for Science and Technology, Shanghai, China

B. W. Zhang
Northeast Dianli University, Jilin, China

F. Q. Huang
University of Shanghai for Science and Technology, Shanghai, China

M. Yu
University of Shanghai for Science and Technology, Shanghai, China

M. Lu
University of Shanghai for Science and Technology, Shanghai, China

L. Li
University of Shanghai for Science and Technology, Shanghai, China

To be presented in this paper are nonlinear characters of natural convection in an annulus with an internal concentric slotted cylinder. The engineering background of this work is natural convection heat transfer in enclosed isolated-phase buses used in power plants. Numerical simulations have been performed using SIMPLE algorithm with QUICK scheme for the nonlinear phenomena of natural convection, and oscillation and bifurcation are studied. For the numerical simulations, an unsteady mathematical model is adopted and the whole annulus with an internal concentric slotted cylinder is taken as the solution domain. It can be found from the numerical results that even though the all boundary conditions are steady and symmetrical about the vertical central line, the flow and heat transfer in the annulus are oscillatory and unsymmetrical when the Rayleigh number is over a critical value Ra_c2, and when the Rayleigh number is over another critical value Ra_c1, two different flow patterns can be obtained using different initial conditions, i.e. the numerical solution is not unique. The values of two critical Rayleigh numbers Ra_c1 and Ra_c2 are dependent on the slot width S of slotted inner cylinder. Ra_c1 and Ra_c2 at different slot widths are given numerically in this paper by gradual approaching method.

MTH-17 pages DOI: 10.1615/IHTC13.p9.170 Download article

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