Experimental Study And Simulation Analysis Of Electric Field And Small-scale Flame Interaction

From80s, the power MEMS is developing on an unprecedented scale. The power extracted from the combustion of fuel in the micro-burner. Thus, the study on phenomenon of micro-combustion becomes necessary. In micro-combustion, the micro-flame is unstable and easy to turn off because of some inherent characteristic such as the larger combustion surface to volume ratio and the shorter fuel residence time. This point now becomes the bottleneck of the development of power MEMS. In recent years, a lot of researchers at home and aboard have obtained some achievement on the easing flame extinction. However, they did not solve this problem fundamentally. In this paper, the interaction between the electric field and micro-flame was analyzed mainly by experiment research and supplemented by numerical simulation. The purpose of this research is to enhance the stability of micro-combustion.The bench of electric field and small-scale flame interaction is built in the paper. The influence of different electric field conditions on small-scale diffusion flame and small-scale premixed flame and the influence of electrode combination parameters on small-scale flame are studied by applying AC and DC field to the small-scale flame external. Experimental results show that AC and DC field has a certain impact on small-scale flame shape, flame propagation speed, flame temperature and flame conductivity. In the under of electric field excitation, the flame temperature increases, the degree of ionization increases and the electron density in the flame increases. The specific electric field conditions can strengthen the small-scale combustion, but too strong electric field will make the small-scale flame blow out. The experimental results of the influence of electrode combination parameters on small-scale flame indicate that electrodes of different shapes and different heights cause different current.In order to explain the phenomenon observed in the experiment, heat transfer, combustion, and electromagnetic fields are coupled together by multi-physics coupling analysis software COMSOL Multiphysics. Simulation results show that the electron density and electron temperature in the flame increases with the electric field strength in the certain electric field conditions. The electron density and electron temperature are the main factors of the flame resistance, so the variation of the flame conductivity with the external electric field conditions during the experiment can be explained. In addition, the changes of flame shape and spark phenomenon observed during the experimental process can be explained by changes of the internal electric field intensity of the flame according simulation results.To some extent, the research results help to improve the small-scale combustion stability. Appropriate electric field can increase the ion concentration of the small-scale flame, thus enhancing the conductivity of the flame. In this way, appropriate electric field can increase chemical reaction rate and the flame propagation velocity of small-scale combustion.