Air Motion in a Two Stroke Engine Cylinder - The Effects of Exhaust Geometry

Air motion in one cylinder of a Detroit Diesel 6V-92 two stroke diesel engine was studied under steady flow bench test conditions by a laser Doppler anemometer and an axisymmetric finite difference fluid dynamic model. The effects of four different exhaust opening geometries were explored.

Measurements and calculations showed that the swirl induced by the 18 angled inlet ports produced non-uniform axial velocity profiles and large peaks in the mid-radius region (between cylinder center and wall). The exhaust opening geometry in the head of the cylinder influenced these axial velocity fields especially in the upper region of the cylinder. The study concluded that more uniform flow, which is favorable to the scavenging process, can be achieved by an exhaust opening located close to the cylinder periphery.