Transient Flow Characteristics Of Internal Mixing Air Atomizer Based On Large Eddy Simulation

Two-phase flow nozzles use the interaction between gas and liquid phases to break up and atomize the liquid,so the flow characteristics of the two-phase flow inside the nozzle directly affect the fragmentation of the external jet.The flow changes inside the nozzle are a transient process,and it is very difficult to conduct experimental studies on them.Therefore,this article studies the flow characteristics of the internal mixing air-assisted atomization nozzle in two-phase flow by numerical simulation methods.Water and air were used as the media,and the physical models were the Volume of Fluid(VOF)multiphase flow model and Large Eddy Simulation(LES)turbulent flow model.The research mainly focused on the internal profile of the nozzle,different sections inside the nozzle,and the flow parameters at the outlet section.The main research results are as follows:(1)From the internal profile study of the nozzle,it was found that when the liquid flow rate is constant,the highest pressure and maximum velocity inside the nozzle increase with the increase of the air-liquid mass flow rate ratio(ALR),and the pressure and velocity changes mainly concentrate near the inlet of the nozzle.When the ALR is constant,the highest pressure and maximum velocity inside the nozzle also increase with the increase of the liquid flow rate,and the range of pressure and velocity changes become larger.(2)From the study of different sections inside the nozzle,it was found that when the liquid flow rate is constant,the proportion and area of liquid phase volume fraction on the same section decrease with the increase of ALR,and the range of velocity gradient changes increases.When the ALR is constant,the proportion and area of liquid phase volume fraction on the same section increase with the increase of liquid flow rate,and the velocity gradually increases,and the range of velocity changes becomes larger.(3)From the radial data changes at the outlet section,under the same flow rate,as the ALR increases,the overall value of the radial liquid phase volume fraction curve decreases,and the overall value of the velocity curve increases.Under the same ALR,the larger the liquid flow rate,the larger the overall value of the radial liquid phase volume fraction curve;under the same ALR,the larger the liquid flow rate,the larger the maximum value of the radial velocity curve,and the minimum value will be smaller.(4)From the fluctuation characteristics of the data with time at the outlet section,it was found that with the increase of ALR,the overall value of gas content,gas velocity,liquid velocity,and momentum flux curves all increase,and the overall value of gas density curve decreases.The fluctuation curves of gas content and gas density are more stable,while the fluctuation curves of gas velocity,liquid velocity,and momentum flux have larger fluctuations.With the increase of liquid flow rate,the overall value of gas velocity,liquid velocity,gas density,and momentum flux fluctuation curves all increase,while the overall value of gas content fluctuation curve decreases.The fluctuation curves of gas content and gas density have larger fluctuations,but the fluctuation characteristics of gas velocity,liquid velocity,and momentum flux curves are not significantly different.