Numerical simulation of fully developed turbulent flow and heat transfer in annular-sector ducts

The mixing length theory is employed to simulate the fully developed turbulent heat transfer in annular-sector ducts with five apex angles (θ₀ = 18, 20, 24, 30, 40°) and four radius ratios (R_o/R_i = 2, 3, 4, 5). The Reynolds number range is 10⁴-10⁵. The numerical results agree well with an available correlation which was obtained in following parameter range: θ₀ = 18, 20, 24, 30, 40°, R_o/R_i = 4 and Re = 10⁴-5 × 10⁴. The present work demonstrates that the application range of the correlation can be much extended. Apart from the mixing length theory, the k-ε model with wall function and the Reynolds stress model are also employed. None of the friction factor results predicted by the three models agrees well with the test data. For the heat transfer prediction the mixing length theory seems the best for the cases studied.