Wall modeled Large-Eddy Simulations in rotating systems for applications to turbine blade internal cooling

Abstract

Large-Eddy Simulations (LES) has been used extensively in capturing the physics of anisotropic turbulent flows. However, near wall turbulent scales in the inner layer in wall bounded flows makes it unfeasible for large Reynolds numbers. This study evaluates the use of a wall model for LES of a rotating turbulent channel flow at Reb = 34,000 and a rotating ribbed duct at Reb = 20,000 with comparisons to wall resolved LES and experiments. It is found that compared to calculations on the same grid without a wall model, the wall model plays an important role in correct predictions in turbulent channel flow. However, it is not that effective in the ribbed duct. It is reasoned that the turbulent flow and heat transfer characteristics in the ribbed duct are largely driven by shear layer separation and reattachment which is independent of the wall model, but largely dependent on the turbulence generated in the shear layer. It is shown that the coarse grid in the ribbed duct captures the gross effects of Coriolis forces and predicts mean heat transfer augmentation and attenuation to within 15–20 % of wall resolved LES on the leading and trailing sides of the duct at a cost about 150th of the fully wall resolved LES.