Natural Convection Heat Transfer in Enclosure with Uniformly Heated Inner Elliptic Cylinder and Outer square Cylinder


Experimental and numerical simulation study for natural convection heattransfer formed by uniformly heated inclined elliptical cylinder concentricallylocated in an enclosed square cylinder subjected to the ambient have beeninvestigated. Experiments have been carried out for Rayliegh number ranges from0.9×106 to 3.3×106. The enclosure angles of inclination are f =0o (horizontal), 45o(inclined), and 90o (vertical), and for axis ratio of elliptic cylinder(minor/major=b/c) of 1:2, while the dimensions of outer square cylinder was0.5×0.5×2 m. A numerical simulation was conducted by using commercialFluent CFD code to investigate the steady laminar natural convective heattransfer for air between a heated elliptic cylinder and its square enclosure. Itcovered a range of hydraulic radius ratios (HRR) of 1.97, 2.62, and 3.93 andfor orientation angles j = 0o (the major axis is vertical), 30o, 45o. Twovalues of Rayligh number were taken: 0.9×106 and 3.3×106. The experimentalresults showed that the heat transfer process improves as Rayliegh numberincreases and is better in f =0o than other angles of inclination at the sameheat input. Theoretical results showed that the HRR, Rayligh number, andangle of orientation have significant effect on the physical behavior ofstremlines and isotherms inside the equivalent annular gap.