Thermal Transport Phenomena in Turbulent Gas Flows Through a Tube With High Constant Wall Temperature

Abstract

A numerical study is performed to investigate thermal transport phenomena in turbulent gas flow through a tube with high uniform wall temperature. A k-ε turbulence model is employed to determine the turbulent viscosity and the turbulent kinetic energy. The turbulent heat flux is expressed by Boussinesq approximation in which the eddy diffusivity of heat is determined by a t2¯-εt heat-transfer model. The governing boundary-layer equations are discretized by means of a control volume finite-difference technique and numerically solved using a marching procedure. It is disclosed from the study that: (i) Like in a pipe with high uniform wall heat flux, laminarization takes place in a turbulent gas flow through a pipe with high uniform wall temperature, (ii) Once laminarization occurs, both velocity and temperature gradients at the wall diminish along the flow, resulting in a substantial reduction in both the turbulent kinetic energy and temperature variance across the whole tube cross section, and (iii) these attenuations cause a deterioration in heat transfer performance.