There is three main scavenge method used in a two-stroke diesel engine. To better understand its application and working we will consider two stroke marine diesel engines. The three main scavenging types are; loop, uniflow, and cross-flow. loop and cross-flow don’t require a dedicated exhaust valve while the uniflow scavenging method does.

The three main types of scavenging for two stroke engines are cross flow, uniflow and loop flow. Notice on the below image that the cross flow and loop flow scavenging designs use ports only, whilst the uniflow design uses valves (for exhaust) and ports (for inlet).

Modern two-stroke engines use either Schnuerle scavenging (also known as "loop scavenging") or uniflow scavenging. The scavenge or scavenging port refers to that port through which clean air enters the cylinder, the exhaust port through which it leaves.