EXPERIMENTAL AND NUMERICAL STUDY OF BUOYANCY-INDUCED FLOW AND HEAT-TRANSFER IN AN OPEN ANNULAR CAVITY

This paper presents experimental and numerical results for natural con vection in a horizontal, annular cavity which communicates with the su rroundings through its open end. In the experimental study, a known he at flux was applied to each component of the cavity (inner cylinder, i nner cylinder tip, outer cylinder and end-wall) and local surface temp erature measurements were made to determine heat transfer characterist ics of the convective flow. Trends in the experimental data have been explained in terms of the physical mechanisms underlying the buoyancy induced flow. Smoke flow visualization using laser-induced lighting wa s performed to understand the flow field around. the open end of the c avity. The heat transfer results were correlated by Nu(av) = 0.0131(Ra )(0.378) for the range of Rayleigh numbers considered (1.3 x 10(9) < Ra < 5.1 x 10(9)) in the experiments. In the numerical investigation, solutions to the three-dimensional time-averaged (Reynolds') steady-s late equations of fluid motion and heat transfer, were obtained using a finite element analysis. Results of the conjugate study including th e local temperature distributions, heat transfer coefficients and the flow field showing the interactions between the ambient and cavity flo w fields agreed favorably with experimental results. The present work provides, for the first time, validated heat transfer data for high Ra yleigh number buoyancy-induced flows in open annular cavities. Copyrig ht (C) 1996 Elsevier Science Ltd.