Mixture Formation Process in a Diesel Spray with High Injection Pressure. Analysis of Diesel Spray impinging upon a Flat Wall.

Abstract

We propose a newly developed measuring technique for the simultaneous concentration measurement of fuel vapor and liquid in an evaporating diesel spray. This measurement technique is based on the principle of the laser light attenuation caused by the ultraviolet light absorption by fuel vapor and caused by the visible light scattering by fuel droplets in the α-methylnaphthalene diesel spray. Applications have been made of this new measuring technique to an evaporating diesel spray impinging upon a flat wall with high injection pressure. With an increase in the injection pressure, the vaporization of fuel droplets near the impingement point and the entrainment of ambient gas into the spray are enhanced, so the distribution of the fuel vapor along the impingement wall becomes more homogeneous. In the case of an impinging spray, an optimum impinging distance exists for facilitating the evaporation of liquid droplets and the entrainment of the ambient gas.