Laminarization of annular duct flow (Part 3 symmetric heating)

Experimental and numerical procedures were applied to convective heat transfer in the annular channel with both inner and outer tubes heated. The authors\u27modified k-ε turbulence model sufficiently predicted the measured streamwise variation of the Nusselt number on each side of the annular channel. In the high flux case, the sudden deviation from the turbulence correlation was observed from both experimental and numerical results. Calculated radial profiles of the turbulence energy and the streamwise mean velocity showed the same behavior as the flow laminarization within the circular tube. It was found, therefore, that the heat transfer characteristic for the symmetrically heated annulus was definitely different from the one with only the inner tube heated. Moreover, obtained criteria for the occurrence of the laminarization were in full agreement with the existing experimental results for the circular tube flow