Unsteady RANS simulation of turbulent flow and heat transfer in ribbed coolant passages of different aspect ratios. (English) Zbl 1189.76276

Saha, Arun K.; Acharya, Sumanta

Int. J. Heat Mass Transfer 48, No. 23-24, 4704-4725 (2005).

Summary: The flow and heat transfer in ribbed coolant passages of aspect ratios (AR) 1:1, 4:1, and 1:4 are numerically studied through the solution of the unsteady Reynolds averaged Navier-Stokes (URANS) equations. The URANS procedure, which utilizes a two equation \(k-\varepsilon \) model for the turbulent stresses, is shown to resolve large-scale bulk unsteadiness. The computations are carried out for a fixed Reynolds number of 25,000 and density ratio of 0.13, while the Rotation number is varied between 0.12 and 0.50.
At higher rotation numbers (\(\geqslant 0.5\)) at least three inter-rib modules are required to ensure periodicity in the streamwise direction. The flow exhibits unsteadiness in the Coriolis-driven secondary flow and in the separated shear layer. The average duct heat transfer is the highest for the 4:1 AR case. For this case, the secondary flow structures consist of multiple roll cells that direct flow both to the trailing and leading surfaces. The 1:4 AR duct shows flow reversal along the leading surface at high rotation numbers. For this AR, the potential for conduction-limited heat transfer along the leading surface is identified. The friction factor reveals an increase with the rotation number, and shows a significant increase at higher rotation numbers (\(\sim Ro = 0.5\)).

MSC:

76F25	Turbulent transport, mixing
76M20	Finite difference methods applied to problems in fluid mechanics
80A20	Heat and mass transfer, heat flow (MSC2010)