TRANSIENT CONJUGATED FORCED CONVECTION IN TURBULENT PIPE FLOWS

Abstract

This work deals with the problem of transient conjugated forced convection heat transfer in turbulent pipe flows. The external surface of the pipe over a finite heated section is subjected to either uniform heat flux or uniform wall temperature. The governing parameters indentified in this work are the Reynolds number Re, the wall-to-fluid conductivity ratio K, the wall-to-fluid diffusivity ratio A, the dimensionless wall thickness Δ, and the Prandtl number Pr. A modified tow-Re κ-ε turbulent model is adopted to solve for the fully developed velocity and eddy viscosity distributions. Predicted results show that effects of wall conduction and wall heat capacity have a significant impact on the unsteady heat transfer, especially in the early transient period.