A Dynamic Model and Measurement Technique for Studying Induction Air Swirl in an Engine Cylinder

A dynamic engine model and measurement technique have been developed to study induction air swirl in the cylinder of a 4-stroke-cycle engine. Fabrication of the cylinder and piston crown of the model from transparent plastic permitted flow visualization. Local mean flow directions were determined qualitatively using a tuft grid. Paddle wheels were used to determine the gross swirl characteristics of the flow. A single sensor hot wire anemometer placed in three orientations was used to measure the three orthogonal components of local mean velocity. An error analysis indicated that the technique gives results accurate within ±20 percent. The methods developed allow measurements under actual dynamic conditions of the gross swirl characteristics of different flows, as well as the detailed velocity fields at any time during the intake stroke. Sample results are presented to illustrate the application of the methods.