Image Analysis of a Diesel Spray Impinging on a Wall

Behavior of diesel spray moving along a flat wall was experiment.ally investigated for further understanding of a mixing process between diesel spray and surroundings. Internal structures of impinging spray injected into a high-pressure atmosphere were visualized by YAG laser. Inclined angle of wall against the spray axis was varied from 4 to 90 deg. In order to estimate the substantial penetration of impinging spray, spray path length was defined and it was measured as a function of time. Density of spray in a photograph was analyzed by an image processing. When the impingement angle was small, a stratified flow of dense spray was remained along the wall. The inflection point of the spray penetration rate was not affected by the impingement. These phenomena led to a decrease of momentum exchange between spray and surroundings. On the other hand, in the case of deep impingement, the spray behavior changed from axial to radial jet on the wall. The inflection point of the spray penetration rate was fixed on the impingement point and coherent structure of the dense spray appeared on the wall.