Spray-to-Spray Interactions after Wall Impingement

In a direct injection diesel engine, liquid fuel was injected through a multi-hole injection nozzle to a combustion cavity. The spray impingement on the cavity wall made the quick mixing of sprayed fuel and air. Then the spray impingement process was considered as the key process of the mixture formation, and this process was widely investigated. Since the cavity had too small space for free movement of plural sprays injected by a multi-hole injection nozzle, sprays after impingement were interacted together on the cavity wall. This movement was generally recognized but the detail behavior was not yet clarified. In this study, single shot diesel spray injected into a high-pressure test vessel, in which the impingement plate was mounted, was used to investigate the above movement. To observe the fundamental characteristics of the mutual interaction between plural diesel sprays impinged on a wall, two parallel diesel sprays those were closely spaced were impinged vertically to the flat wall. Each impingement spray made the secondary wall spray that was spreading along the wall. When the impingement points of two sprays were closely arranged, secondly wall sprays were interacted each other. A new spray movement was developed and a swelled spray was formed along the interaction line of these secondly wall sprays. The shape of swelled spray was remarkably changed with the spray spacing and wall distance. Also, the ambient pressure influenced the spray shaping of the swelled spray. These phenomena were discussed comparing with a single impingement spray.