Measurement Of Spray Droplet Size Distribution And Information Entropy Analysis

Sprays was widely used in lots of field during engineering, it has significant aspect in improving combustion and emission characteristics of internal combustion engine, drop size distribution is supposed to a important target of spray atomization and obtain lots of interesting in the research of spray. This paper take a photo of spray under different pressure, structures of atomizers and fuel component to analysis the macrocosmic characteristic including atomization cone angle and penetration. As the influence of high viscocity and surface tension of diesel, the spray was long and thin, we also found that as the pressure increase, cone angle and penetration are also increased, the same influence as atomizer hole diameter decrease. When gasoline was add into diesel, cone angle increased, also with the penetration. Laser Particle Analysis was used to measure the drop size of sprays in different axial and radial distance under different pressure, atomizer structure and fuel. The results shown that as the increase of axial and radial distance, the SMD decreased and the percent of small drop increased, higher pressure and smaller hole diameter can clearly decrease SMD and improve the atomization of sprays. we also input gasoline into diesel to found its influence to the drop size distribution, and found with lower viscocity and surface tension coefficient gasoline's addition can help to improve the atomization of diesel.Information entropy theory is widely used in spray research to predict the drop size distribution, this paper establish restrained condition under the conservation of mass and energy ,obtain drop size distribution function using Laplace Multipier Method and Newton-Raphson Method. A Matlab program was write to get the drop size distribution function under the mass mean diameter 50μm, 70μm. We found that the drop size distribution deserved by Information entropy theory was narrow, most drop distribution near the mass mean diameter. We also compare the theory result and experiment result, and found the trend was nearly the same, expect the experiment results was widely distributed but the theory results was narrowly distributed.