Experimental And Numerical Investigation On Electrostatic Spray Atomization And Combustion Of Fuel

Turbulent spray combustions are encountered in a variety of engineering applications, such as aircraft engines and automobile engines. The atomization of liquid fuel spray plays an extremely important role in the process of combustion. It has directly impacts on the evaporation rate of liquid fuel spray, then greatly influences the combustion rate of liquid fuels. Thus, the research on turbulent spray atomization is of significant value. The method of electrostatic atomization helps improve the atomization quality of spray. In this method, essential advantage of electrostatic atomization can be combined with those of automobile fuel spray. The experimental research and numerical simulation of liquid fuel spray were studied in this dissertation. The main contents and achievements of the thesis were outlined as below:Based on the Large Eddy Simulation (LES), the Probability Density Function (PDF) method was introduced to derive the transport equation of the fluid velocity seen by the particles, and then an LES/FDF (Filtered Density Function) model was developed for two-phase flow. The droplets breakup was simulated with KH-RT droplet breakup model, the characteristic of randomness and instantaneity and the effect of static electricity on droplet breakup were fully taken into consideration. A set of numerical models was established and a computer program was developed to numerically investigate the turbulent spray atomizationThe charging system of high voltage static electricity was established, and had the fuel spray charging to form charged droplets effectively. Experimental system of combustion of fuel spray was designed to measure temperature distribution in combustion chamber and to gauge tail gas component when fuel spray combusting. The particle size analyzer was used to measure droplet size distribution under two operating conditions, which showed the regular pattern of droplet size distribution at different positions.Based on the computational program in this thesis, the process of atomization in a model combustor was simulated with LES-FDF model and KH-RT droplet breakup model. The droplet mean size (SMD) and droplet size distribution were obtained and had a good agreement with experimental data. It was shown that the numerical models in this thesis can accurately predict the process of transportation and atomization of fuel spray. The impact of electrostatic on atomization was able to help obtain fuel spray with better atomization quality.