The gas turbines are highly demanded in modern industries, and the improvement of the performance derives from the increase of the turbine inlet temperature. Various cooling structures are used, such as ribs, pin fins, to improve heat transfer performance and extend the lifespan of the blade. Due to the limitations of the measurement technique, magnified geometry models have been tested with similarity theory in the past. In this paper, a thermochromic liquid crystal experiment was conducted to investigate the heat transfer performance of a magnified rectangular channel with ribs, supplemented with numerical simulation. The results indicated that the vortex and secondary flow generated by the ribs enhance the local heat transfer. Moreover, the thermal performance of the rib-roughed rectangular cooling channel was calculated under different scale factor conditions. The quantitative correlation equations of Nusselt number and friction coefficient versus the scale factor were established. Nusselt number showed an exponential growth with the increase of scale factor, while the friction coefficient displayed an exponential decay. Compared with the baseline, the enhanced heat transfer coefficient is improved by 18.7% and the normalized friction coefficient is dropped by 8.2% with geometry scaled up 10 times.
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