Uniflow Scavenging

the process of removing exhaust gases from a cylinder of a two-stroke engine and filling the cylinder with a fresh charge. In the process, the fresh charge is forced through scavenging ports, and the exhaust gases are discharged through exhaust ports or special valves located at the other end of the cylinder. The ports are opened and closed by the piston as it moves within the cylinder. In diesel engines, uniflow scavenging is performed by pure air and in carburetor engines, by the fuel-air mixture.