Evaluation of heat transfer performances of various rib shapes

The heat transfer and friction loss performances of rib-roughened rectangular cooling channels having a variety of cross-sectional rib shapes were analyzed using three-dimensional Reynolds-averaged Navier–Stokes equations. Numerical simulations were conducted for sixteen rib shapes: square, isosceles triangular, fan-shaped, house-shaped, reverse cut-trapezoidal, cut-trapezoidal, reverse boot-shaped, boot-shaped, reverse right-angle triangular, right-angle triangular, reverse pentagonal, pentagonal, reverse right-angle trapezoidal, right-angle trapezoidal, isosceles trapezoidal, and semicircular ribs. The ratios of pitch, height, and width of the rib to hydraulic diameter of the channel were set to 10, 0.047, and 0.047, respectively. The Reynolds stress model was used with the Speziale–Sarkar–Gatski pressure–strain model to analyze the turbulence. The computational results for the area-averaged Nusselt number were validated by comparison with the experimental data under the same conditions. The effects of the Reynolds number and rib pitch-to-width ratio on the performances of various ribs were also investigated for Reynolds numbers of 5000–50,000 and rib pitch-to-width ratios of 5.0–10.0, respectively. The new boot-shaped rib design showed the best heat transfer performance with a pressure drop similar to that of the square rib.