Role of jet core in splashing patterns of diesel jet impingement on a solid wall

Abstract

Under certain conditions diesel jet wall impingement results in triangular (polygonal) splashing shapes. This process has been found to be almost independent of injection pressure, injection frequency or of the injection duration. The triangular splashing shapes are observed at a given transition time after diesel jet wall contact. This time depends on the distance from the wall and on the injection pressure (jet velocity). This triangular splashing process is dependent on the distance from the wall, and does not correspond to a typical hydraulic jump process. The wall jet created after jet impingement along the solid wall is not responsible for triangular splashing. The process investigated depends on the degree of the diesel jet development and is characterized by impingement of the jet core on the wall only. A hypothesis of a non-homogeneous jet core has been formulated and verified to explain triangular splashing regions.

For very small distances between nozzle and wall, the resulting splashing may be observed as a star-like three-jet structure. These jets, rebounding in three pre-dominating directions, will spread the preliminary circular splashing (just after wall contact of the primary jet), rendering the splashing geometry more and more triangular in shape until the transition time occurs.

Keywords

jet core wall impingement polygonal splashing diesel spray

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