The behavior of diesel spray impinging on an inclined wall was experimentally investigated in a pressurized vessel. To clarify the wall effect on a diesel spray, a relative angle of the inclined wall to a spray axis was varied. Spray penetration along the wall was observed optically and it was compared with that of a free spray. To evaluate various spray motion quantitatively, a spray path penetration which described a development of a spray tip along the wall was newly introduced. To observe an internal structure of the spray, it was visualized by a YAG laser sheet light and its tomographic image was captured on a film. The photo-image on a film was taken into an image analyzing computer using a high resolved image scanner. A high density zone in the tomographic image was extracted to clarify the internal structure of an impinging spray.
The main parameter of the relative position of the wall was its inclined angle which was defined as the angle between the spray axis and wall. In this study, this angle was varied. from 10 deg to 90 deg (vertical impingement).
The penetration along spray path after impinging was smaller than a free spray. However, if the spray path penetration was measured from an impingement point and it was plotted on logarithmic diagram with an elapsed time from impingement, the spray path penetration on the wall increased with the root of this elapsed time. Its behavior was similar to a radial gas jet which was radially stretching on a plane. When the spray was impinging on a shallowly inclined wall, the high density zone of after impinging spray was very near to the wall. It seemed that the spray moved along the wall as a thin spray layer. When the spray was impinging deeply or vertically on the wall, the high density zone on the wall separated from the wall surface.