The overall thermal performance enhancement in an internal cooling channel by the hierarchical-truncated rib scheme

In an internal cooling channel, the overall thermal performance enhancement is studied under various hierarchical-truncated rib schemes via the computational fluid dynamics simulation. The simulation result shows that in a wide Reynolds number range, the low-pressure recirculation region behind ribs is significantly compressed by the linearly decreased rib height. Hence, with the linearly decreased rib height, the pressure drop penalty is significantly less under the hierarchical rib scheme than that under the non-hierarchical rib scheme, resulting in the overall thermal performance enhancement under the hierarchical rib scheme. In comparison with other hierarchical rib schemes, the distribution of smooth fluid flows, transverse vortices, and spanwise vortices is better under the hierarchical fractal-truncated rib scheme. Hence, under the hierarchical fractal-truncated rib scheme, there is better thermal performance. The overall thermal performance under the hierarchical fractal-truncated rib scheme is further enhanced by optimizing the distribution of smooth fluid flows, transverse vortices, and spanwise vortices. As a result of the optimized distribution, the best thermal performance is simultaneously realized by the optimized gap length and the optimized rib spacing in the wide Reynolds number range, which is composed of the significant heat transfer enhancement and the extreme flow loss reduction.