LAMINAR FORCED-CONVECTION IN THE ENTRANCE REGION OF HELICAL PIPES

In the present study, three-dimensional laminar forced flow and heat t ransfer in the entrance region of helical pipes have been investigated using a fully elliptic numerical method. Laminar flow and heat transf er were assumed to develop from the inlet to the outlet simultaneously . The governing equations were solved by means of a control-volume fin ite element method. The results presented in this paper cover a Reynol ds number range of 250-2000, a pitch range of 0.0-0.6, and a curvature ratio range of 0.025-0.20. The present elliptic numerical results are compared with previous experimental data and parabolic numerical data . The developments of temperature field, main and secondary velocity f ields, local and average friction factors, and local and average Nusse lt numbers are given and discussed. It has been found that both the fr iction factor and Nusselt number are oscillatory in the entrance regio n of helical pipes. The pitch and Reynolds number exert different effe cts on the developments of the friction factor and Nusselt number than the curvature ratio. (C) 1997 Elsevier Science Ltd.