| Summary: | 博士 === 大同大學 === 機械工程學系(所) === 93 === ABSTRACT
Experimental and numerical study has been performed to investigate the combined effects of lid movement and buoyancy on flow pattern and heat transfer characteristics for the mixed convective flow inside an arc-shape cavity. The governing equations in terms of the stream function-vorticity formulation are solved by the finite-volume method coupled with a body-fitted coordinate transformation scheme. In experiments, steady-state temperature data are measured by K-type thermocouples, and the flow field is visualized by using kerosene smoke.
The task of the present study includes the numerical and experimental investigation of
(1) Natural convection heat transfer and flow pattern in the horizontal and the inclined cavities.
(2) Steady mixed convection heat transfer and flow pattern in the horizontal cavities with a moving lid.
(3) Unsteady (periodic) mixed convection heat transfer and flow pattern in the horizontal and the inclined cavities, particularly under the effects of irregular shape and lid oscillation.
Results show that only when the inertial and buoyant forces are of approximately equal strength the periodic flow pattern can be observed. For an inertia-dominant or buoyancy-dominant situation, the periodic flow pattern is not visible. Flow pattern, friction factor, and Nusselt numbers are investigated in wide ranges of parameters. Close agreement in the comparison between the predicted and the visualized flow patterns has been found. In these above ranges of the parameters, two kinds of oscillatory flow pattern have been observed, namely, the traversing-periodic and the half-periodic patterns. Attention has been focused on the effects of the inclination effects on the occurrence of these two different oscillatory flow patterns. Meanwhile, periodic variation in the mixed convection heat transfer accompanying the oscillatory moving lid has also been studied, and the results for the local and the overall Nusselt numbers are presented. This report is also concerned with transient behavior of a buoyancy-induced periodic flow in different lid-driven cavities with different cross-sectional shapes. Periodic flow patterns and heat transfer characteristics for various geometries are predicted.
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