In order to analyze the spray characteristics of non-circular nozzle holes based on the air-assisted spray system, the spray characteristics of circular and non-circular nozzles were studied under the pressure of 0.2-...In order to analyze the spray characteristics of non-circular nozzle holes based on the air-assisted spray system, the spray characteristics of circular and non-circular nozzles were studied under the pressure of 0.2-0.6 MPa and the spray volume of 1000-5000 mL/h. Elliptical nozzle and triangular nozzle are classified as non-circular geometries. The spray cone angle was measured by processing the spray image captured by a CCD camera. The measured spray cone angles of the circular nozzles were analyzed, and the axis switching phenomenon of minor plane of elliptical nozzle was found during the test. Among the three shapes of nozzles, the elliptical nozzle had the largest spray cone angle, and the triangular nozzle had the smallest. The velocity field obtained depended on the PIV system. The results show that for axial velocity, elliptical orifice spray has greater kinetic energy and smaller droplet size under the same working parameters. Compared with the circular and elliptical nozzles, triangular orifice reached maximum spray velocity the fastest, but its velocity decay was the fastest. For radial velocity, away from the axis, the spray velocity of the elliptical orifice was less affected by the injection parameters, and the velocity was less than that of circular orifice and triangle orifice. Increasing air pressure will weaken radial propagation. The increase of liquid spraying rate had no remarkable effect on the increase of spraying rate. The results of particle size analysis show that the particle size of the non-circular orifice is reduced compared with that of the circular orifice, which promotes the breakup of droplets to a certain extent and enhances the atomization effect.展开更多
The structure of the pressure swirl nozzle is an important factor affecting its spray performance.This work aims to study pressure swirl nozzles with different structures by experiment and simulation.In the experiment...The structure of the pressure swirl nozzle is an important factor affecting its spray performance.This work aims to study pressure swirl nozzles with different structures by experiment and simulation.In the experiment,10 nozzles with different structures are designed to comprehensively cover various geometric factors.In terms of simulation,steady-state simulation with less computational complexity is used to study the flow inside the nozzle.The results show that the diameter of the inlet and outlet,the direction of the inlet,the diameter of the swirl chamber,and the height of the swirl chamber all affect the atomization performance,and the diameter of the inlet and outlet has a greater impact.It is found that under the same flow rate and pressure,the geometric differences do have a significant impact on the atomization characteristics,such as spray angle and SMD(Sauter mean diameter).Specific nozzle structures can be customized according to the actual needs.Data analysis shows that the spray angle is related to the swirl number,and the SMD is related to turbulent kinetic energy.Through data fitting,the equations for predicting the spray angle and the SMD are obtained.The error range of the fitting equation for the prediction of spray angle and SMD is within 15% and 10% respectively.The prediction is expected to be used in engineering to estimate the spray performance at the beginning of a real project.展开更多
Air-atomized fog cooling is particularly suitable for the after-pot cooling of galvanized steel strips.With air and water serving as working media,an experimental study was conducted on the atomization characteristics...Air-atomized fog cooling is particularly suitable for the after-pot cooling of galvanized steel strips.With air and water serving as working media,an experimental study was conducted on the atomization characteristics of a newly-developed cross-flow type of fog nozzles.The water flux distribution,spray angle and pressure of water and air were measured.The results show that the water droplet size was small and insensitive to the water flow rate.The spray angle was small and the water flow rate slightly affected the air pressure in the chamber.An empirical correlation between the pressure in the chamber and the gas flow rate was obtained for the purpose of equipment design.展开更多
The application of anti-drift nozzles,such as air-induction nozzles,is the most common recommendation for reducing spray drift;To reduce the risk of coarse droplets bouncing and rolling produced by anti-drift nozzles,...The application of anti-drift nozzles,such as air-induction nozzles,is the most common recommendation for reducing spray drift;To reduce the risk of coarse droplets bouncing and rolling produced by anti-drift nozzles,various types of adjuvants were screened by comparing their atomization performance,surface tension and contact angle,in order to identify favourable adjuvants that are compatible with anti-drift nozzles.It was found from the study results that the addition of 50%neem crude oil emulsifiable concentrate(neem oil),isomeric alcohol ethoxylates and BYK-405 all significantly decreased distribution span(S)and the percentage of droplet size less than 150μm(ΦVol_(<150μm))values,but significantly promoted the median volume(D_(50))value.And the surface tension measurement results showed that all tested adjuvants significantly reduced the surface tension,while neem oil,FC4430 and silwetl-77 were observed with a most significant effects;Furthermore,all tested adjuvants except BYK-051N could also significantly decrease the contact angle,and the difference between neem oil,FC4430 and silwetl-77 was significant.Wind tunnel test results clearly demonstrated that the application of IDKA(a combination of air-induction nozzle IDK120-01 and neem oil)substantially decreased the drift deposition amount;In addition,the field experiments revealed that IDKA possessed a significantly improved deposition amount per unit area on canopy or bottom,leading to a more effective deposition.These results suggest that the use of IDK120-01 nozzle and neem oil can effectively reduce spray drift,lessen surface tension and enhance spreading.展开更多
In this paper,the atomization characteristics of Si3N4 ceramic dry granulation affect the performance of Si3N4 ceramic bearing balls.In order to improve the dry granulation characteristics and the comprehensive perfo...In this paper,the atomization characteristics of Si3N4 ceramic dry granulation affect the performance of Si3N4 ceramic bearing balls.In order to improve the dry granulation characteristics and the comprehensive performance of Si3N4 ceramic bearing balls,the atomization mechanism of the spinning nozzle used for Si3N4 dry granulation was studied in detail.The interaction between air and binder in the pressure-swirl nozzle is analyzed based on VOF method,the modified realizable k−εturbulence model is used to simulate the flow field inside and outside the pressure-swirl nozzle,the effects of nozzle inlet parameters including the number of tangential inlets and the deflection angle of tangential inlets on the binder volume fraction,velocity distribution and pressure distribution are analyzed.The results show that when the number of tangential inlets increases from 1 to 4,the swirl strength of gas–liquid two-phase in the nozzle increases,the mean diameter of air core increases from 1.51 mm to 2.01 mm,and the spray cone angle increases from 18.5◦to 26.4◦.Besides,when the deflection angle of tangential inlet increases from 0◦to 15◦,the swirl strength of gas–liquid two-phase in the nozzle with the deflection angle of tangential inlet of 10◦is the largest,and the mean diameter of air core and spray cone angle is 3.04 mm and 30.7◦,respectively.Based on the atomization experiment platform of the electric control fuel system,the mean diameter of air core and spray cone angle are measured,the micromorphology of Si3N4 particles is observed,which verifies the correctness of numerical simulation.When the Si3N4 particles are prepared by dry granulation,taking the atomization performance of nozzle into consideration,the pressure-swirl nozzle with 4 tangential inlets and 10◦deflection angle should be selected.展开更多
基金Sponsored by the National Key R&D Project(Grant No.2019YFD1002500)the Key Projects of Science and Technology Support Plan of JiangsuP rovince(Grant No.BE2016341)the Open Fund of State Key Laboratory of Internal Combustion Engine(Grant No.GKF2015-004)。
文摘In order to analyze the spray characteristics of non-circular nozzle holes based on the air-assisted spray system, the spray characteristics of circular and non-circular nozzles were studied under the pressure of 0.2-0.6 MPa and the spray volume of 1000-5000 mL/h. Elliptical nozzle and triangular nozzle are classified as non-circular geometries. The spray cone angle was measured by processing the spray image captured by a CCD camera. The measured spray cone angles of the circular nozzles were analyzed, and the axis switching phenomenon of minor plane of elliptical nozzle was found during the test. Among the three shapes of nozzles, the elliptical nozzle had the largest spray cone angle, and the triangular nozzle had the smallest. The velocity field obtained depended on the PIV system. The results show that for axial velocity, elliptical orifice spray has greater kinetic energy and smaller droplet size under the same working parameters. Compared with the circular and elliptical nozzles, triangular orifice reached maximum spray velocity the fastest, but its velocity decay was the fastest. For radial velocity, away from the axis, the spray velocity of the elliptical orifice was less affected by the injection parameters, and the velocity was less than that of circular orifice and triangle orifice. Increasing air pressure will weaken radial propagation. The increase of liquid spraying rate had no remarkable effect on the increase of spraying rate. The results of particle size analysis show that the particle size of the non-circular orifice is reduced compared with that of the circular orifice, which promotes the breakup of droplets to a certain extent and enhances the atomization effect.
基金supported by the National Key Research and Development Program(2022YFB3504000)the National Natural Science Foundation of China(22122815,21978296)the NSFC-EU project(31961133018)。
文摘The structure of the pressure swirl nozzle is an important factor affecting its spray performance.This work aims to study pressure swirl nozzles with different structures by experiment and simulation.In the experiment,10 nozzles with different structures are designed to comprehensively cover various geometric factors.In terms of simulation,steady-state simulation with less computational complexity is used to study the flow inside the nozzle.The results show that the diameter of the inlet and outlet,the direction of the inlet,the diameter of the swirl chamber,and the height of the swirl chamber all affect the atomization performance,and the diameter of the inlet and outlet has a greater impact.It is found that under the same flow rate and pressure,the geometric differences do have a significant impact on the atomization characteristics,such as spray angle and SMD(Sauter mean diameter).Specific nozzle structures can be customized according to the actual needs.Data analysis shows that the spray angle is related to the swirl number,and the SMD is related to turbulent kinetic energy.Through data fitting,the equations for predicting the spray angle and the SMD are obtained.The error range of the fitting equation for the prediction of spray angle and SMD is within 15% and 10% respectively.The prediction is expected to be used in engineering to estimate the spray performance at the beginning of a real project.
文摘Air-atomized fog cooling is particularly suitable for the after-pot cooling of galvanized steel strips.With air and water serving as working media,an experimental study was conducted on the atomization characteristics of a newly-developed cross-flow type of fog nozzles.The water flux distribution,spray angle and pressure of water and air were measured.The results show that the water droplet size was small and insensitive to the water flow rate.The spray angle was small and the water flow rate slightly affected the air pressure in the chamber.An empirical correlation between the pressure in the chamber and the gas flow rate was obtained for the purpose of equipment design.
基金financially supported by the National Key R&D Program of China(Grant No.2018YFD0200300).
文摘The application of anti-drift nozzles,such as air-induction nozzles,is the most common recommendation for reducing spray drift;To reduce the risk of coarse droplets bouncing and rolling produced by anti-drift nozzles,various types of adjuvants were screened by comparing their atomization performance,surface tension and contact angle,in order to identify favourable adjuvants that are compatible with anti-drift nozzles.It was found from the study results that the addition of 50%neem crude oil emulsifiable concentrate(neem oil),isomeric alcohol ethoxylates and BYK-405 all significantly decreased distribution span(S)and the percentage of droplet size less than 150μm(ΦVol_(<150μm))values,but significantly promoted the median volume(D_(50))value.And the surface tension measurement results showed that all tested adjuvants significantly reduced the surface tension,while neem oil,FC4430 and silwetl-77 were observed with a most significant effects;Furthermore,all tested adjuvants except BYK-051N could also significantly decrease the contact angle,and the difference between neem oil,FC4430 and silwetl-77 was significant.Wind tunnel test results clearly demonstrated that the application of IDKA(a combination of air-induction nozzle IDK120-01 and neem oil)substantially decreased the drift deposition amount;In addition,the field experiments revealed that IDKA possessed a significantly improved deposition amount per unit area on canopy or bottom,leading to a more effective deposition.These results suggest that the use of IDK120-01 nozzle and neem oil can effectively reduce spray drift,lessen surface tension and enhance spreading.
基金The author would like to thank the National Natural Science Foundation of China(NSFC)for its grant to this research.The number of the fund is 51964022.
文摘In this paper,the atomization characteristics of Si3N4 ceramic dry granulation affect the performance of Si3N4 ceramic bearing balls.In order to improve the dry granulation characteristics and the comprehensive performance of Si3N4 ceramic bearing balls,the atomization mechanism of the spinning nozzle used for Si3N4 dry granulation was studied in detail.The interaction between air and binder in the pressure-swirl nozzle is analyzed based on VOF method,the modified realizable k−εturbulence model is used to simulate the flow field inside and outside the pressure-swirl nozzle,the effects of nozzle inlet parameters including the number of tangential inlets and the deflection angle of tangential inlets on the binder volume fraction,velocity distribution and pressure distribution are analyzed.The results show that when the number of tangential inlets increases from 1 to 4,the swirl strength of gas–liquid two-phase in the nozzle increases,the mean diameter of air core increases from 1.51 mm to 2.01 mm,and the spray cone angle increases from 18.5◦to 26.4◦.Besides,when the deflection angle of tangential inlet increases from 0◦to 15◦,the swirl strength of gas–liquid two-phase in the nozzle with the deflection angle of tangential inlet of 10◦is the largest,and the mean diameter of air core and spray cone angle is 3.04 mm and 30.7◦,respectively.Based on the atomization experiment platform of the electric control fuel system,the mean diameter of air core and spray cone angle are measured,the micromorphology of Si3N4 particles is observed,which verifies the correctness of numerical simulation.When the Si3N4 particles are prepared by dry granulation,taking the atomization performance of nozzle into consideration,the pressure-swirl nozzle with 4 tangential inlets and 10◦deflection angle should be selected.