Velocity and Temperature Profiles in Turbulent Channel Flow at Supercritical Pressure

摘要

Understanding the effects of property variations on velocity and temperature profiles is important for the accurateprediction of supercritical heat transfer in regenerative cooling channels. In this study, direct numerical simulationsof a planar turbulent channel flow with a wall-normal temperature gradient were conducted to understand the meantemperature profiles that are affected by property variations at supercritical pressure. The working fluid used wassupercritical nitrogen. The density ratios between two walls were four and eight. The Van Driest transformation forthe mean velocity profiles holds true in the present conditions. This result implies that discussions based on a mixinglength hypothesis are valid for the conditions that were studied. Mean temperature profiles in the viscous sublayer arecorrelated to those of incompressible constant-property flows using a local Prandtl number. For the meantemperature profiles in the logarithmic region, a new temperature transformequation that accounts for the variationin mean density and isobaric specific heat was introduced. It was demonstrated that the gradients of temperatureprofiles transformed by the transform equation coincide with the ones in incompressible constant-property flows inthe logarithmic region.