Search Results

In an air-cooled engine, waste heat dissipates from the cylinder, through the cooling fin, to the cooling air. This cooling air is kept moving by a cooling fan in most utility engines, and by the relative motion in moving motorbikes. However, such cooling becomes less efficient when air is not forced around the cylinder, e.g., in utility engines without cooling fans and in stationary motorbike engines. Here, the temperature may increase in the space between the fins, decreasing the heat release from the cylinder. In an effort to increase natural convection in the cylinder, and so decrease the temperature between the fins, we produced special cooling fins with slits arranged in a fixed equiangular spiral. We tested experimental cylinders, varying the fin slit widths and slit setting positions, and measured the temperature inside the cylinder to determine the heat release from the cylinder.

Several techniques facilitate the cooling of air-cooled motorbike engines. Baffle plates, mounted between cooling fins symmetrically with respect to a plane through the axis of the cylinder, maximize the distance that the cooling air follows the cylinder surface before it separates from the cylinder, when the motorbike is in motion. Cooling ports, drilled in the fins parallel to the axis of the cylinder, induce natural convection in the cylinder, when the motorbike is stationary. We produced cylinders with baffle plates between the fins, and with cooling ports, in order to improve cylinder cooling while motorcycles are both moving and stationary. We investigated experimental cylinders with baffle plates, cylinders with fins with cooling ports, and cylinders with both baffle plates and fins with cooling ports, all over a range of air velocities between 0 and 60 km/h.