In the current automotive scenario, particulate filter technology is mandatory in order to attain emission limits in terms of particulate matter for diesel engines. Despite the fact that the Diesel Particulate Filter (DPF) is often considered a mature technology, significant issues can result from the use of the engine fuel injectors to introduce into the exhaust pipe the fuel needed to ignite the particulate matter accumulated in the filter during its regeneration. The most important issue is lubricant oil dilution with fuel as a consequence of significant spray impact on the cylinder liner. As an alternative, the fuel required to start DPF regeneration can be introduced in the exhaust pipe by an auxiliary low-pressure injector spraying in the hot exhaust gas stream. In these conditions, the spray evolution and its possible interaction with the surrounding gas stream are relevant in order to better identify the overall layout of the system, so as to have the fuel vaporized at the DPF inlet section.
In the present paper, a detailed spray analysis of a low pressure diesel spray evolving in a pressurized, high temperature vessel is described; the vessel pressure ranged from ambient to 2 bar, g, while the air temperature in the vessel was varied from 100 to 500 °C.
The spray evolution was investigated in terms of tip penetration and cone angle; the spray sizing was quantified by magnified imaging, obtaining significant data about the effect of the ambient temperature and pressure on the spray atomization process.