IMAGING OF VAPOR/LIQUID DISTRIBUTIONS OF SPLIT-INJECTED DIESEL SPRAYS IN A TWO-DIMENSIONAL MODEL COMBUSTION CHAMBER

Abstract

The ultraviolet-visible laser absorption-scattering (LAS) technique was extended to simultaneous imaging of two-dimensional vapor/liquid mass distributions in a nonaxisymmetric evaporating diesel spray such as that injected into a two-dimensional model combustion chamber of direct-injection diesel engines. The main error for vapor measurement is incurred by the temperature dependence of molar absorption coefficients (TDMAC) of the test fuel. Thus, selecting a test fuel of negligible TDMAC can greatly increase the measurement accuracy. By means of this extended LAS technique, the overall mass, as well as the mass distribution of vapor and liquid phase per projection area perpendicular to the laser beam, was obtained, and then the behavior of split-injection diesel spray in a two-dimensional model combustion chamber in a high-temperature high-pressure constant-volume vessel was observed. Finally, the effects of injection mass ratios on the distributions of vapor and droplets and characteristics of fuel/air mixing were examined.