Technical Paper
Measurements of Flows During Scavenging in a Two-Stroke Engine
1991-02-01
910671
This paper introduces a new measurement technique into the field of engine diagnostics. LlPA (Laser lnduced Photochemical Anemometry) is used to measure velocities and velocity gradients over a chosen plane in a motored two-stroke engine during scavenging. The LlPA technique consists of tracking a phosphorescing grid which is created by laser lines directed into the flow. A 308nm pulsed excimer laser beam is divided into 15 lines which are sent through the appropriate optics to create the grid. The grid energizes the seed chemical that is premixed in the carrier gas. The seed chemical used consists of a mixture of phosphorescent gases with nitrogen as the carrier. The results are not bias by out of plane motions, or the inertia or the charge of particles. In each plane forty-four simultaneous points of data are taken with an approximate grid mesh size of 3mm × 3mm. These measurements are taken over thirty consecutive cycles.