THERMAL TRANSPORT PHENOMENA IN TURBULENT GAS-FLOW THROUGH A TUBE AT HIGH-TEMPERATURE DIFFERENCE AND UNIFORM WALL TEMPERATURE

A numerical study is performed to investigate thermal transport phenom ena in turbulent gas flow through a tube heated at high temperature di fference and uniform wall temperature. A k-epsilon turbulence model is employed to determine the turbulent viscosity and the turbulent kinet ic energy. The turbulent heat flux is expressed by a Boussinesq approx imation ill which the eddy diffusivity of the heat is determined by a <(t(2))over bar>-epsilon(t) heat transfer model. The governing boundar y layer equations are discretized by means of a control-volume finite difference technique and are numerically solved using a marching proce dure. It is disclosed from the study thar (i) laminarization takes pla ce in a turbulent gas flow through a pipe with high uniform wall tempe rature just as it does in a pipe with high uniform wall heat flux, and (ii) the flow in a tube heated to high temperature difference and uni form wall temperature is laminarized at a lower heat than that under t he uniform heat flux condition.