Abstract
Heat transfer experiments have been conducted for strongly heated gas flow in an annular duct. Special attention is paid to the laminar-turbulent transitional region. The results show that laminarization was not observed within the range of the experiments, although this phenomenon took place in a heated circular pipe when other conditions were the same. Above a certain heat flux, the heat transfer coefficient in the downstream region tends to follow a new correlation : Nus=0.071Re0.6b Pr0.4b, which is independent of the heat flux. Numerical analyses are made using three types of turbulence models : k-kL-(uv)^^-, k-ε-(uv)^^-, and k-εmodels. The calculations were compared with the measurements, and better agreement was obtained for the k-kL-(uv)^^- model.
