Spray and self-ignition visualization in a DI diesel engine
Spray and self-ignition have been visualised in a DI diesel engine designed to provide a large optical access, no spray impingement and thermodynamic conditions close to those of commercial engines. The spray from a single hole injector and the combustion zone can be fully observed. Laser induced exciplex fluorescence is used to provide information on the spray structure as well as penetration. Data from these two techniques were collected for a range of operating conditions involving changes of air temperature, pressure in the cylinder, injected quantity and engine speed. Initially, the liquid and vapour advance at the same speed. After a short while, the liquid phase stops while the gas phase continues. Self-ignition occurs in a region of high mean shear quite close to the nozzle, at the level of the liquid phasetip. This is explained by the presence of coherent structures in the liquid spray creating favourable self-ignition sites. This mechanism was confirmed by simultaneous self-ignition and liquid Mie scattering visualisations.
Bibliographic Reference: Paper presented: The 1994 SAE International Congress, Detroit (US), February 8 - March 4, 1994
Availability: Available from (1) as Paper EN 38103 ORA
Record Number: 199410295 / Last updated on: 1994-11-28
Original language: en
Available languages: en