Spray/wall interaction analysis on an ECN single-hole injector at diesel-like conditions through Schlieren visualization

Abstract

[EN] To continuously improve CFD models which simulate spray evolution, breakup and evaporation mechanisms, it is helpful to validate them with results obtained by experimental research. In the present study, a mono-orifice target nozzle from Engine Combustion Network, referred to as Spray D, was investigated at conditions of spray-wall interaction, which actually is a real situation in internal combustion engines that is not frequently analyzed by visualization. A Photron SA-X2 high-speed camera was employed to record the vapor phase development of the spray in an inert atmosphere using a Schlieren imaging single-pass setup. The experiments show that the spreading of the spray along the wall has a behavior fairly similar to penetration at free-jet situations, especially regarding to its susceptibility to the operating conditions and its proportionality to the square root of time once the spray reaches a steady regime interacting with the wall. Furthermore, the spray film thickness was measured at three distances from the spray-wall impact point during the injection event, thereby characterizing that parameter both spatially and temporally. The tests were carried out in a constant pressure-flow facility able to reproduce pressure and temperature conditions, similar to those seen into a diesel engine. In order to observe the behavior of the spray colliding with a wall within this test rig, a system capable to being fitted into it and to holding a fused quartz wall at different injector tip-wall distances and impingement angle configurations, was designed and employed.