Soot Suppression Of Acetylene Diffusion Flames By Acoustic Oscillated Combustion

In recent years,with the increase of car ownership year by year,how to reduce the emission of pollutants from vehicle exhaust has become a subject of many scholars.Acoustic oscillated combustion has attracted attention due to its high combustion efficiency,high heat transfer rate,high combustion intensity and low NOx emission.Acoustic oscillated combustion can effectively inhibit the generation and emission of soot particles during combustion,but the generation mechanism and emission rule of soot particles under acoustic oscillated combustion have not been systematically studied and understood.Therefore,the research on the mechanism of pulsating combustion to suppress the generation and emission of soot particles is conducive to the exploration of a new technology and method to control the emission of pollutants from automobile exhaust,which has important academic significance and industrial application value for energy utilization and environmental protection.Paper has conducted a acoustic oscillated combustion inhibit soot particles generated and discharge mechanism of the research,design and build the acetylene forced diffusion flame pulsation test bench,and by changing the force ripple amplitude,frequency,source distance and change the burner nozzle shape,using a single speaker to studyparameters such as pulse under the condition of acetylene soot particle generation process in the diffusion flame and pulsation of acetylene diffusion flame soot suppression effect.The physical and chemical properties of soot particles produced by combustion under different conditions were studied by scanning electron microscope,X-ray diffractometer and elemental analyzer.The main conclusions are as follows:(1)With the increase of amplitude,the soot suppression was significantly improved.At a frequency of 40 Hz and an amplitude of 0.02 V,the soot suppression rate was more than 90%.The increase of amplitude can result in the decrease of soot particles.Compared with the combustion without acoustic oscillated,the particle size of carbon smoke particles produced by combustion decreases by half when the acoustic oscillated frequency is applied at 40 Hz and the amplitude is 0.02 V.(2)When the amplitude remains unchanged,the inhibition rate of soot first increases with the increase of frequency,and reaches the optimal frequency under the condition of 40 Hz.With the increase of frequency,the soot suppression began to decrease.When the frequency is greater than 80 Hz,the frequency continues to increase,and the soot suppression is basically unchanged.The change of pulsation frequency has no obvious influence on the size of soot particles.(3)The soot suppression effect of the triangular nozzle has the bestperformance in all working conditions.The circular nozzle is the second,followed by the square nozzle,and the rectangular nozzle has the worst performance.And at the frequency of 60 Hz,the soot suppression effect of the triangular nozzle is nearly 30% higher than that of the rectangular nozzle.The change of nozzle shape has no significant effect on the particle size of soot particles.(4)Under the condition of not affecting the flame combustion,the closer the sound source distance of the speaker is,the better the carbon smoke suppression effect will be.Under the condition of 60 Hz,the soot suppression was nearly 15% different between the sound source distance of 1 cm and the sound source distance of 2 cm.Under the condition of not affecting the flame combustion,reducing the distance of sound source can effectively reduce the particle size of soot particles.(5)The soot suppression of the speaker installed on one side is far less than that of the loudspeaker installed on both sides.And at the frequency of 60 Hz,the soot suppression of the speakers installed on both sides is nearly 40% higher than that of the speakers installed on one side.With the increase of pulse frequency,the gap gradually narrowed to 25%.(6)By applying acoustic oscillated to the flame,agglomeration of carbon smoke particles can be inhibited and oxidation of carbon smoke particles can be promoted,so as to make the particles smaller and finally achieve the purpose of inhibiting the generation of carbon smoke.(7)Applying pulsating waves has no influence on the composition of the soot particles produced by combustion.