Numerical study on flow and heat transfer characteristics of pin-fins with different shapes

Equipping pin-fins in the blade trailing edge is an significant method for enhancing heat transfer. In order to obtain a geometry of pin-fins with good heat transfer effect and small friction factor, six pin-fins (circular, elliptic, oblong, teardrop, lancet and NACA) are selected. The flow and heat transfer features of the rectangular channel with the staggered pin-fins were numerically studied through FLUENT software. The channels with different pin-fins have the same relative spanwise pitch (S/D=2.5) and streamwise pitch (X/D=2.5), and the range of Reynolds number is 5×10³ to 3×10⁴. The applicability and accuracy of five turbulence models (Standard κ-ε, Realizable κε, RNG κ-ε, Standard κ-ω and SST κ-ω) are checked by comparing the numerically predicted results with the experimental from literature. It is found that the Realizable κ-ε model is better at capturing the microstructure of flow field and has higher precision in predicting the averaged Nusselt number on the heated surface. For the six pin-fins, the leading edge is surrounded by a "U-shaped" strong heat exchange zone, but the vortex systems in the trailing edge are different from each other. Compared to the circular pin-fin, the oblong pin-fin has the best heat transfer enhancement effect, but the friction factor of channel is also larger. While the NACA pin-fin has the lowest friction factor, and the heat transfer effect is second only to the oblong. NACA pin-fin may be applied in blade trailing edge cooling by further optimizing the relative position of the pin-fins in the channel.