Numerical Simulation Of Gas-liquid Two-phase Atomizing Nozzles With Different Shapes

With the rapid development of high-yield and efficient integrated coal mining technology in coal mines,coal mine dust has also increased.Coal mine dust brings major disasters to coal mine enterprises.It will not only cause coal mine dust explosion,cause failure and wear of coal mine equipment,but also cause pneumoconiosis,which poses a threat to the health of the people.In addition,the generation and diffusion of atmospheric particulate matter(such as PM2.5,etc.)have increased many health and safety hazards for urban residents.There are a variety of methods for dust deposition,among which spray dust reduction is the most used.Spray dust reduction uses pressure water and pressure air to generate fine water mist,improve the efficiency of wetting,adsorption,adhesion and sedimentation in the process of removing dust during dust reduction,and can significantly control the air.Dust and particulate content.The gas-liquid two-phase atomizing nozzle is one of the nozzles for spray and dust reduction,and has the characteristics of high atomization efficiency and wide application.In this paper,the simulation of gas-liquid two-phase atomization simulation is carried out to study the characteristics of gas-liquid two-phase atomization and the optimization of nozzle parameters.The numerical simulation shapes of different gas-liquid two-phase atomization are thoroughly studied,and the working parameters and structural parameters are revealed.The influence of atomization characteristics provides a theoretical basis for research and development of its products.First of all,this paper analyzes the atomization principle,droplet breakage,droplet surface wave breakage mechanism and atomization principle of Laval gas-liquid two-phase flow nozzle using fluid mechanics and spray theory.Using the design theory of the internal contour of the gas-liquid two-phase flow high-speed nozzle,a three-dimensional Laval gas-liquid two-phase flow nozzle model was established.Using the discrete phase model calculation method,the mathematical model of the gas-liquid two-phase flow nozzle calculation flow field was selected.The numerical simulation calculations of the internal and external flow fields of the gas-liquid two-phase nozzle were carried out,and the influence laws of the turbulent flow energy,velocity distribution and gas-liquid two-phase distribution under different fluid parameters and structural parameters were analyzed..The analysis results show that the nozzle spool inside the gas-liquid two-phase flow nozzle can produce supersonic flow,which has a significant effect on increasing the gas-liquid two-phase velocity difference and is conducive to improving the atomization performance of the gas-liquid two-phase flow.Then,the mathematical models of circular,rectangular and regular hexagonal nozzles were established,and ICEM was used to mesh and verify the grid independence.The model was further numerically simulated for the three-dimensional flow field of the atomization of the gas-liquid two-phase flow nozzle.The calculation of the internal flow field and the calculation of the external flow field were carried out.Then,the numerical simulation of the unsteady discrete phase was performed to obtain the nozzle.After the atomization of the spray flow field,the effect of different initial conditions on the atomization effect of the nozzle was analyzed.The research shows that the increase of air pressure and gas-liquid pressure ratio and the decrease of water pressure are conducive to the reduction of droplet size.Under the same conditions,the gas-liquid two-phase flow nozzle is superior to the original cone in atomization performance and effect.nozzle.By analyzing the influence of nozzles with different shapes and structures on the size and distribution of the droplet size SMD,it was obtained under certain conditions(gas flow rate 3.6 m~3/h,4.8 m~3/h,6m~3/h,water flow rate 0.43 m~3/h,0.57 m~3/h,0.72m~3/h),the water flow rate is constant.As the gas flow rate increases,the droplet size of the droplets generally shows a decreasing trend.When the water flow rate is close to the gas flow rate,the fog The droplet size increases;under the same gas flow rate,as the water flow rate increases,the droplet size generally shows an increasing trend.The effect of the structural parameters in the gas-liquid two-phase flow nozzle on the droplet characteristics of the gas-liquid two-phase spray was analyzed through experiments.The results show that the change of the valve core of the Laval structure nozzle in the current nozzle has a certain effect on the spray effect.When the inner contour of the nozzle is a regular hexagon,its atomization effect is significantly improved.