Large eddy simulation of turbulent forced gas flows in vertical pipes with high heat transfer rates

摘要

Large eddy simulation (LES) of vertical turbulent pipe flows with significant property variations has been performed to investigate the effects of high heat fluxes on the turbulent structures and transport. The Cartesian-based, compressible filtered Navier-Stokes equations were solved using a second-order accurate finite volume method. Low Mach number preconditioning was used to enable the compressible code to perform efficiently at low Mach numbers. A dynamic subgrid-scale stress model accounted for the subgrid-scale turbulence. In this study, the simulations were designed to simulate the experiments of Shehata and McEligot with three different near-constant heat fluxes. Step-periodic boundary conditions based on a quasi-developed assumption were used. The predicted integral parameters and mean velocity and temperature profiles agreed well with the experimental data. The fluid structures have been distorted due to high heat fluxes leading to significant property variations in the near wall region. The results showed that strong heating resulted in remarkable reductions of turbulent intensities, shear stresses, and turbulent heat flux. Apparent "laminarization" of the flow has been observed.