Numerical simulation of developing compressible turbulent flow with heat transfer

Abstract

This study investigates the effects of wall heating and skin friction on the characteristics of a compressible turbulent flow in developing and developed regions of a pipe. The numerical solution is performed by finite-element-based finite volume method applied on unstructured grids. A modified κ-ε model with a two-layer equation for the near-wall region and a compressibility correction are used to predict turbulent viscosity. The results show that shear stress in fully developed flow is nearly constant from the centerline up to 75% of the pipe radius, then increases sharply next to the wall, and the ratio of the turbulent viscosity to the molecular one is less than 0.2. Under a uniform wall heat flux condition, the friction factor decreases in the entrance region and will be fully developed after Z/D > 50, but the Nusselt number increases first and then will be fully developed after Z/D > 10. In addition, the heat flux accelerates the developing compressible flow and causes the entrance length to decrease, unlike the incompressible flow.