Air side heat transfer and fluid flow characteristics of slotted fin surfaces with arc-type and X-type strip arrangement in a pressurizing air cooler were studied by visualization experiments. Experiments were conducted out by a particle image velocimetry(PIV)system and an infrared thermo tracer to visualize the flow field and the temperature distribution of two slotted fin surfaces. The experimental results show that the pressure drop of the arc-type slotted fin surface is lower than that of the X-type slotted fin surface and the former contributes more to improving the heat transfer performance at the back of the tube. However

the integrated heat transfer performance and field synergy character of the latter are superior to those of the former. According to the merits of the two slotted fin surfaces

a new type slotted fin surface(X-arc type)was designed. Heat transfer and fluid flow characteristics of three slotted fin surfaces were simulated and the results agree well with the experiments data. Numerical simulation results show that the field synergy character and heat transfer performance of the optimized fin surface are better than those of the other two slotted fin surfaces. Within Reynolds number range from 800 to 3 400

the integrated heat transfer performance of the new designed fin surface is about 7%-15% higher than that of arc-type fin surface and 3%-9% higher than that of X-type fin surface.