Experimental study of fluid flow and heat transfer characteristics in the square channel with a perforation baffle

This work performed a detailed measurement of local heat transfer coefficients in a square channel with a perforation baffle by using the transient liquid crystal themography. The varied parameters were the Reynolds number, the baffle height, and the hole numbers on the perforation baffle. The results showed that the enhancements of local heat transfer appeared in the leading edge of the baffle due to the impinging effect, which was more significant when Reynolds number became larger or the baffle height became higher. Additionally, the heat transfer coefficients off center were better than those in the center at downstream of the baffle. It might be resulted from two secondary flows, which appeared off center after the airflow passed through the baffle. Baffles with various hole numbers but having same total hole area were also studied to find the heat transfer enhancement. The results depicted that the back facing step flow which had characteristics of backflow and flow reattachment had an important effect on the heat transfer characteristics at downstream of the baffle. Finally, the correlation for the location of the flow reattachment point (Xr) was proposed.