Abstract
Keywords
optical technique, geometrical optic, light intensities, rainbow angle of dispersion, diameter and temperature of droplet.
Abstract
The principal object of this study is an application of the latest technique for measuring the characteristics of the droplets in a spray of Internal Combustion Engine. These essential characteristics consist of the velocity, diameter and the temperature, which allow a better knowledge of the formation and the development of fluid flow in this spray. The behavior of velocity and size of the droplets are respectively determined by Laser Doppler Velocity and phase Doppler measurement technique. Moreover, this size is also measured by method of Global Rainbow Thermometry, which delivers simultaneously the average temperature of droplets. The average diameter of the droplet can be obtained, basically on Airy’s theory, from the fringe distance of two first inflexion points of the rainbow figure; while the refractive relative index, between the liquid and the environment, can be deduced from the first fringe angle of this figure according to the geometrical optic. Thus, the droplet temperature, which is a function of the mass density, the incident wavelength, and the water refractive index, is deduced from the value of the obtained refractive index. Experimental measurements are then carried out at the LMFA laboratory (Ecole Central de Lyon, France) in three types of configuration for confirming the interest of this simple not - intrusive method.