Study On Atomization Characteristics And Field Application Of A New Type Sonic Explosion Nozzle

As the pillar energy in China,the rapid development of social economy is accompanied by the continuous increase of coal consumption.With the continuous development and improvement of science and technology,the modernization level of coal mines has gradually improved,and the incidence of coal mine safety accidents has decreased year by year.However,the incidence of coal mine pneumoconiosis has increased year by year,and the underground dust concentration has seriously exceeded the standard.At present,spray dust removal technology is the most widely used method in China,among which gas-liquid spray dust removal technology is the main one,and the key core of this technology is the gas-liquid two-phase flow nozzle.Although some research progress has been made on this nozzle,there are still some problems such as low speed and poor matching of droplet size produced by gas-liquid two-phase flow spray technology,resulting in unsatisfactory dust removal effect in various dust production links.Therefore,based on the principle of sonic boom atomization,this paper puts forward a sonic boom atomization technology which is different from the traditional spray method,and develops a new type of sonic boom atomization nozzle according to Laval dynamics principle.Firstly,the mathematical model of sonic boom atomizing nozzle is established,and then the specific size parameters of the inner valve core structure of sonic boom atomizing nozzle are determined according to experience and theoretical calculation formula.Self-built experimental platform of sonic boom atomization characteristics was set up,and the proportional relationship between the contraction section-throat section-expansion section of nozzle inner valve core was defined.Twelve sonic boom atomization nozzles with different structural parameters were selected and divided into three groups to carry out atomization characteristics experiments,and the influence law of different parameters on nozzle atomization performance under different proportional coefficients and the same proportional coefficients was explored.When the proportional coefficient is the same,the droplet size gradually decreases with the increase of the size parameters of the sonic boom atomizing nozzle under the constant water supply pressure and air supply pressure,so the droplet sizes ofα₉,α₁₀,α₁₁andα₁₂are the smallest among the 12 kinds of sonic boom atomizing nozzles.Each group contains four kinds of scale coefficients.With the increase of scale coefficients,the median diameter of droplets in each group shows a trend of first decreasing and then increasing.When the scale coefficients areα2,α6 andα10,the droplet size parameters reach the lowest,that is,when the scale relationship isβ₃（2.6:1:2）,the droplet size is the smallest.According to the above conclusion,it can be seen that No.10 nozzle is the best nozzle,and the droplet size parameter is the lowest under different operating parameters.Compared with the traditional internal mixing nozzle,it is found that the peak particle size and droplet size distribution range of the sonic explosion atomizing nozzle are smaller than those of the traditional internal mixing nozzle.Water supply pressure,air supply pressure and other operating conditions play a vital role in the atomization performance of nozzles.Change air pressure and water pressure to explore the influence of operating conditions on atomization performance.The results show that when the water supply pressure is constant,with the increase of the air supply pressure,all the parameters characterizing the droplet size gradually decrease.With the increase of water supply pressure,all parameters of droplet size increase.Different proportions of sonic boom atomizing nozzles and different operating conditions will affect the spray range.Under the condition of constant water supply pressure and air supply pressure,when the proportional relationship increases,the spray range first increases and then decreases,reaching the highest value when the proportional relationship isβ₃（2.6:1:2）.When the water supply pressure is 0.3MPa,the spray range of four sonic boom atomizing nozzlesα₉,α₁₀,α₁₁ andα₁₂ increases first and then decreases with the increase of the water supply pressure,and the inflection point is 0.6MPa.Taking the return air gateway of the former 31116 fully mechanized mining face in Lijiahao Coal Mine as the research background,the field dust suppression test was carried out,and design the intelligent monitoring dust suppression system of sonic boom fog curtain.The CCZ20 mine dust sampler is used to test the concentration of all the four test sites before and after spraying,and it is found that the average dust suppression rates of the whole dust and the blowing dust are 91.26%and 90.16%respectively after the sonic boom atomization dust suppression system is started,which verifies the feasibility of the sonic boom atomization nozzle in underground application technology.