Study On The Combustion Characteristics Of Droplets In The Ultrasonic Standing Wave Field

At present and for a long time to come,liquid fuel,which is representative of petroleum,will still occupy a very important position in the energy structure.There is a strong interaction between combustion and sound,and the introduction of ultrasonic technology is expected to expand the scope of the existing combustion and combustion control technology,promote energy conservation and emission reduction and sustainable development of energy.A deep understanding of the mechanism of acoustic-combustion interaction is the key to realize the use of sound waves to regulate the combustion process,and it is also a necessary prerequisite to improve the combustion efficiency of liquid fuel by using sound field.In this paper,several hydrocarbon fuels represented by n-heptane were used as research targets,and the combustion characteristics of stationary droplets under different acoustic conditions were explored by combining numerical simulation with experiment,so as to reveal the mechanism of sound acting on liquid fuel combustion.The main work and achievements are as follows:1)the experimental system of stationary suspended single droplet combustion in ultrasonic standing wave field was built,and the dynamic measurement of droplet combustion process was completed by combining optical measurement means.In this paper,the influence of different acoustic positions on droplet combustion is discussed.The experimental results show that three typical flames appear in the stationary droplet in the ultrasonic standing wave field.In other words,enveloping flame appears at the antinode of the sound pressure wave and lifting flame appears in different directions at the node of the sound pressure wave.2)numerical simulation was carried out based on the acoustic radiation model of the finite element software COMSOL multi-physics.The model verified by the experimental results was used to simulate the evaporation characteristics of droplets at different sound field positions.Under the condition of different acoustic sound in the flame is formed by radiation and the outcome of combined action of buoyancy lift,use steam distribution of droplet in different sound field location explains in the causes of the formation of flame,simulation results have good consistency with the experiment,in order to further study acoustic coupling and droplet combustion dynamics combustion process.The work in this paper lays a foundation for revealing the mechanism of ultrasonic wave acting on droplet combustion,and provides detailed experimental data for the study of acoustic combustion coupling and acoustic flow coupling.