Effect of nozzle L/D of gasoline direct injection injectors on spray characteristics under different superheated degrees

The purpose of this experiment is to use Schlieren visualization technology to study the effect of GDI injector nozzle size(L/D) on flash boiling spray. This study first compared the difference in spray morphology and spray density distribution between the two injectors under different superheat conditions. The spray of the two injectors are divided into three regions according to the differences in spray characteristics. Finally, the effect of ambient pressure on the spray characteristics under the same superheat condition is analyzed. It was found that the injector with a larger L/D nozzle has a shorter spray tip penetration and a more uniform spray density distribution in a larger superheat range, which is called transition region. Under the same superheated degree, the spray characteristics are independently affected by the ambient pressure. In addition, injectors with smaller L/D nozzles are more sensitive to changes in ambient pressure.