Numerical Calculations on Flow and Heat Transfer in Smooth and Ribbed Two-Pass Square Channels under Rotational Effects

Abstract

U-shaped channel, which is also called two-pass channel, commonly exists in gas turbine internal coolant passages. Ribbed walls are frequently adopted in internal passage to enhance the heat transfer. Considering the rotational condition of gas turbine blade on operation, the effect of rotation is also investigated for the coolant channel which is close to real operation condition. Thus, the objective of this study is to discuss the effect of rotation on fluid flow and heat transfer performance of U-shaped channel with ribbed walls under high rotational numbers. Investigated Reynolds number is Re=12500and the rotation numbers areRob=0.4and 0.6. In the results, the spatially heat transfer coefficient distributions are exhibited to discuss the effect of rotation and roughened walls. It is found that ribbed walls enhance the heat transfer rate significantly. Under the rotational condition, theNuin the first pass with outward flow is increased while that in the second pass is decreased. Finally, averageNuratio, friction ratio, and thermal performance are all presented to discuss the thermal characteristics.

Influence of turn geometry on turbulent fluid flow and heat transfer in a stationary two-pass square duct

“…Shen et al [14] investigated numerically to discuss the combined effect of ribs and rotation of the duct on fluid flow and heat transfer characteristics in a U-shaped channel. The simulations were performed using SST k-x turbulence model at a Reynolds number of 12,500 and for two rotation numbers namely, 0.4 and 0.6.…”

Numerical Computation of MHD Thermal Flow of Cross Model over an Elliptic Cylinder: Reduction of Forces via Thickness Ratio

“…Due to the interaction between vortices introduced on the cylinders, the phenomenon of shear layer transfer in these flow types provides quite different signatures (see refs. [1][2][3][4][5][6][7][8][9][10][11][12][13]).…”

“…Flow evaluations have been carried out using structured and unstructured grids on the basis of Reynold numbers for steady and unstable flows. Shen et al [6] numerically investigated the effects of thermal features and rotational flow characteristics in ribbed channel at high Reynolds number and also computed the influence on the average Nusselt number. Zainuddin et al [7] numerically examined the free oscillatory convection in the presence of heat generation around the horizontal circular cylinder of a Newtonian fluid by using the final differentiation method.…”