Though predicting heat transfer characteristics in regenerative cooling channels is crucial to thermal designs of liquid rocket engines, past numerical studies have indicated that current Reynolds-Averaged Navier-Stokes (RANS) simulation has poor accuracy in predicting heat transfer characteristics of trasncritical flow with deteriorated heat transfer. Direct numerical simulation (DNS) is an attractive approach to modify turbulence models in RANS simulation. However, Reynolds numbers of DNS simulations are lower than those of real regenerative cooling channel flows due to computational cost problems. In addition, it is unknown whether deteriorated heat transfer can be found in low Reynolds number flow-fields because the mechanism of it is not clarified. In this study, to investigate the mechanism and clarify whether deteriorated heat transfer can be found in low Reynolds number flow-fields, RANS simulations of a turbulent heated channel flow under transcritical condition are conducted on both low and high Reynolds number conditions. The simulations indicate that the wall temperature has a strong relationship with effective thermal conductivity distribution in wall normal direction. The decrease in effective thermal conductivity is showed in the region where the wall temperature gets maximum. That decrease is caused by the deterioration in turbulent thermal conductivity. Those results are common in both low and high Reynolds number simulations.
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