A Study of Diesel Flame Movement by Using the Cross Correlation Method

Flame motion in the middle and late combustion stages of a high-speed direct-injection diesel engine was studied by computerised image-analysis of high-speed photographs. By using a two-dimensional cross-correlation method based on the flame intensity distribution a velocity vector field was obtained, the consistency of which was improved by introducing element rotation into the cross-correlation method. The flow-fields obtained reveal the action of reverse squish and swirl, and these results are discussed in the paper.