Abstract
The quantitative information of the droplets and vapor concentration distributions inside diesel sprays injected into a high-temperature and high-pressure nitrogen atmosphere by a common rail injection system was obtained by means of
UV-visible laser absorption-scattering (LAS) technique. In the LAS technique, the second harmonic (532nm) and the fourth harmonic (266nm) of a Nd:YAG laser was employed as the incident light and dimethylnaphthalene as the test fuel.
The contours of equivalence ratios of vapor-gas mixture and droplets-gas mixture in the diesel sprays were deconvoluted from the UV and visible images of the spray, and the mixture structures of the free sprays and the sprays impinging on a flat wall were examined. The effect of ambient temperature on the fuel distributions in the sprays was inspected. It was found that the perpendicular wall-impingement can enhance the ambient-gas entrainment in the diesel spray in comparison with the free spray.