Research About The Effect Of Atomization On Modification At The End Of Delivery Tube With Close-coupled Atomizer

The microspherical powder was extensively applied in kinds of industry,and gas atomization technology had many advantages such as small particle size?high cooling rate?excellent sphericity?low oxygen content and so on.Close-coulped atomizer as core part of atomizaiton technology was studied extensively.With the development of numerical simulation and visualization technology,the methods played important roles in researching and discussing geometric parameters?flow field?mechanism between gas and liquid?distribution of particle size in atomizing process and so on,which researcher in fluid dynamics was attracted with mechanism of mixture about gas and liquid.Under same atomizing condition yield of microspherical Aluminum powder(d50?10?m)in production can improve from 10%~30% to 50%~85%using chevron modification,but the mechanism of improving mixture quality through modification in melt delivery tube is still almost completely unexplored..Continue in-depth research for them had great significance.In this paper,major work was to modify structure about close-coupled gas atomizer(CCGA)core part and study mechanism mixture in atomizing process.First,using soft fluent to simulate flow field,establishing schlieren device and studying the experiment were carried out.In base of research about number results,operate schlieren experiment,and study influence on atomizing mixture about 3D CCGA with modification on delivery tube.First step,study position and distribution about barrel shape shock and expansion zone.At the same time,carry out numerical simulation with gas and water multiphase,and the results showed that shear layer between bottom of gas jet and boundary of recirculation zone was core of mixture,and recirculation zone always changed shape tending to balance.In base of characters of CCGA,establish jet schlieren device.Under increase of pressure,gas expansionand the spray angle got larged.Schlieren showed that atomizer with ring holes had a function of separated flow,and recirculation zone in which fluctuation cycle is 2 ms and it generated low temperature phenomenon always was affected with fluctuation.Structure of tap and chevron modification on delivery tube improve mixing strengthening,and chevron nozzle had a advantage to change shape of plume jet.Atomizing effect with8 chevron tooth had good mixture than tube with 4 tooth.Second step,propose a new structure about delivery tube and research influence of kinds of structure under different conditions,analyzing the reason.Finally,paper simulated the 3d chevron nozzle with gas phase,capturing flow filed and distribution of parameters.The results stated that comparing with jet of normal nozzle where parameters were uniform and distributed as ring,chevron nozzle was core of generating streamwise vortex,which a chevron root had 7pairs of anti-equivalent streamwise vortexes.The pairs of streamwise vortexes generated strong entrainment motion with environment mediums and led in change of density ? velocity ? temperature(deformed flowfield ? increased shear action and effected cooling rate)and gas liquid rate through axial pressure.Chevron nozzle had more keys than normal nozzle to product microspherical powder...