DETACHED EDDY SIMULATION OF FLOW AND HEAT TRANSFER IN A STATIONARY INTERNAL COOLING DUCT WITH SKEWED RIBS

摘要

Numerical predictions of a hydrodynamic and thermally developed turbulent flow for a unit period of a stationary duct using Detached Eddy Simulation (DES) and Unsteady Reynolds Averaged Navier-Stokes (URANS) are presented. The domain under consideration is a square duct with 45° ribs on the top and bottom walls arranged in a staggered fashion. Computations are carried out for a bulk Re of 47,000. The rib height to channel hydraulic diameter (e/D_h) is 0.1 and the rib pitch to rib height (P/e) is 10. DES is applied on two grids 80 x 80 x 80 and 128 x 80 x 80 and the initial results are compared with the experimental results and LES computations. Based on this the 128 x 80 x 80 grid is chosen for the comprehensive study. DES and URANS computations are carried out on the grid. The rib geometry introduces a strong secondary flow along the rib. The presence of the secondary flow introduces a spanwise variation in the heat transfer. DES predicts flow features and heat transfer distribution which is consistent with the experimental observations and LES computations. The average friction and the augmentation ratios predicted by DES also concur with the earlier observations.