Improving Cylinder Cooling Using Tapered Fins and Baffle Plates between Fins in Air-Cooled Engines 2010-01-0323

We aim to maximize the performance of air-cooled engines (such as motorbike engines and small stationary engines) by increasing cylinder cooling and by maintaining uniform temperature around the cylinder circumference. In typical engine designs, air cools the front of the cylinder better than the rear. In an effort to increase cooling at the rear, this research experiments with tapered fins that contract air flow to the cylinder axis between the fins, and with baffle plates mounted between fins symmetrically with respect to a plane through the axis of the cylinder. In a wind tunnel at air velocities between 20 and 60 km/h, we compared cylinders with conventional fins, cylinders with tapered fins, cylinders with baffle plates between conventional fins, and cylinders with baffle plates between tapered fins. We measured the temperature inside the cylinder to determine the heat release, and we measured the temperature on the fin surface to determine the temperature distribution around the cylinder circumference. We also visualized the air flow over the fin surface, using the oil film method, and between fins, using the smoke wire method, to understand how tapered fins and baffle plates contributed to cylinder cooling. Results indicate that both tapered fins and conventional fins with baffle plates between fins increased cylinder cooling, compared with conventional fins without baffle plates. Furthermore, our cylinder fitted with both tapered fins with the tapered portion closest to the rear, and baffle plates between fins, enjoyed the greatest cylinder cooling.