Heat Transfer Characteristics in a Horizontal Annulus Enclosure with Uniformly Heated Stationary Inner Cylinder and Rotating Outer Cylinder

An experimental and numerical investigations have been carried out to show the effect of rotating outer cylinder on heat transfer and fluid flow for a horizontal annulus filled with air. The rotating outer cylinder was cooled by ambient while the inner cylinder was kept stationary and subjected to uniform heat flux. The dimensionless parameters ranges that studied for this work were rotational Reynold’s number (0 ≤ 𝑅𝑒Ω ≤ 4000), Rayleigh number (2 × 104 ≤ 𝑅𝑎 ≤ 5 × 105), radius ratio η =3 and aspect ratio Ar=11.59. A computational fluid dynamic package ANSYS fluent (R.15) has been used to achieve the numerical simulations. The validation of present results shows a good agreement with previous works. The results show that the effect of increasing Rayleigh number more than the influence of rotational Reynolds number on average heat transfer coefficient since the increasing percentages were 16.33 and 0.0445 respectively. Empirical correlations have been deduced for the average Nusselt number Nu as a function of 𝑅𝑎 only for pure natural convection and as a function of 𝑅𝑒Ω and Ra for mixed convection.