Electrohydrodynamic(EHD)jet printing represents a novel micro/nano-scale additive manufacturing process that utilises a high-voltage induced electric field between the nozzle and the substrate to print micro/nanoscale...Electrohydrodynamic(EHD)jet printing represents a novel micro/nano-scale additive manufacturing process that utilises a high-voltage induced electric field between the nozzle and the substrate to print micro/nanoscale structures.EHD printing is particularly advantageous for the fabrication on flexible or non-flat substrates and of large aspect ratio micro/nanostructures and composite multi-material structures.Despite this,EHD printing has yet to be fully industrialised due to its low throughput,which is primarily caused by the limitations of serial additive printing technology.The parallel multi-nozzle array-based process has become the most promising option for EHD printing to achieve large-scale printing by increasing the number of nozzles to realise multichannel parallel printing.This paper reviews the recent development of multi-nozzle EHD printing technology,analyses jet motion with multi-nozzle,explains the origins of the electric field crosstalk effect under multi-nozzle and discusses several widely used methods for overcoming it.This work also summarises the impact of different process parameters on multi-nozzle EHD printing and describes the current manufacturing process using multi-nozzle as well as the method by which they can be realised independently.In addition,it presents an additional significant utilisation of multi-nozzle printing aside from enhancing single-nozzle production efficiency,which is the production of composite phase change materials through multi-nozzle.Finally,the future direction of multi-nozzle EHD printing development is discussed and envisioned.展开更多
Based on the prototypes of a 130 t/h boiler, constant proportional cold-state test bench is established, flow characteristics of multi-nozzle in natural gas reburning burner and its influence on the covering effect fo...Based on the prototypes of a 130 t/h boiler, constant proportional cold-state test bench is established, flow characteristics of multi-nozzle in natural gas reburning burner and its influence on the covering effect for the upflow in the furnace are researched. Numerical simulations of this process are also made with standard ?turbulence model. The results show that air flow fullness in furnace is better in the case of the reburning zone with 8 nozzles compared to 4 nozzles and also coverage effect of the reburning flow for the updraft gas in the furnace is better. In the condition each nozzle airflow velocity is constant, the effect of reburning flow on coverage of up-secondary air is best when the incident angle for four corners is 14.17?, while Center of the furnace wall is 84.57. And while the best incident angle is invariable, the effect of reburning flow on coverage of up-secondary air is best when the speed of reburning gas in the corners of furnace is 51 m/s, the same to the center of the furnace wall’s.展开更多
During the supersonic re-entry of multi-nozzle heavy rockets into the atmosphere,the basic flow state becomes increasingly complex due to the coupling effect between the retropropulsion plumes and the freestream.A num...During the supersonic re-entry of multi-nozzle heavy rockets into the atmosphere,the basic flow state becomes increasingly complex due to the coupling effect between the retropropulsion plumes and the freestream.A numerical method using the hybrid Reynolds-Averaged Navier-Stokes and Large Eddy Simulation(RES)method and discrete coordinate method is developed to accurately estimate the thermal environment.In addition,finite rate chemical kinetics is used to calculate the afterburning reactions.The numerical results agree well with wind tunnel data,which confirms the validity and accuracy of the numerical method.Computations are conducted for the heavy carrier rocket re-entry from 53.1 km to 39.5 km altitude with 180°angle of attack by using three different Supersonic Retro-Propulsion(SRP)modes.The numerical results reveal that these three SRP flow fields are all Short Penetration Models(SPM).As the re-entry altitudes decrease,both the plume-plume interaction and the plume-freestream interaction become weaker.The highest temperatures in the plume shear layers of the three SRP modes increase by 8.36%,7.33%and 6.92%respectively after considering afterburning reactions,and all occur at a reentry altitude of 39.5 km.As the rocket re-enters the atmosphere,the maximum heat flux on the rocket base plate of three SRP modes stabilizes at 290,170 and 200 kW/m^(2) respectively,but the maximum heat flux on the side wall increases significantly.When the altitude declines to 39.5 km,the extreme heat flux of the three modes increase by 84.16%,49.45%and 62.97%respectively compared to that at 53.1 km.展开更多
This study developed a numerical model to efficiently treat solid waste magnesium nitrate hydrate through multi-step chemical reactions.The model simulates two-phase flow,heat,and mass transfer processes in a pyrolysi...This study developed a numerical model to efficiently treat solid waste magnesium nitrate hydrate through multi-step chemical reactions.The model simulates two-phase flow,heat,and mass transfer processes in a pyrolysis furnace to improve the decomposition rate of magnesium nitrate.The performance of multi-nozzle and single-nozzle injection methods was evaluated,and the effects of primary and secondary nozzle flow ratios,velocity ratios,and secondary nozzle inclination angles on the decomposition rate were investigated.Results indicate that multi-nozzle injection has a higher conversion efficiency and decomposition rate than single-nozzle injection,with a 10.3%higher conversion rate under the design parameters.The decomposition rate is primarily dependent on the average residence time of particles,which can be increased by decreasing flow rate and velocity ratios and increasing the inclination angle of secondary nozzles.The optimal parameters are injection flow ratio of 40%,injection velocity ratio of 0.6,and secondary nozzle inclination of 30°,corresponding to a maximum decomposition rate of 99.33%.展开更多
A novel granulation process that involved the use of a rotary multi-nozzles cup atomizer and water cooling was proposed for ferroalloy manufacturing.The effects of rotating speed and nozzle diameter on the properties ...A novel granulation process that involved the use of a rotary multi-nozzles cup atomizer and water cooling was proposed for ferroalloy manufacturing.The effects of rotating speed and nozzle diameter on the properties of FeSi75 alloy(containing 75 wt.%Si)granules were investigated.Results indicated that median granule diameter decreased as rotating speed in creased,and initially increased and then decreased as nozzle diameter in creased.The optimal conditi ons for the gra nulation of FeSi75 alloy were a rotating speed of 150 r/min and nozzle diameter of 10 or 12 mm.The phase composition,micromorphology,and elemental distribution of the FeSi75 alloy granules were also studied by X-ray diffraction,scanning electron microscopy,and energy-dispersive X-ray spectrometry.In order to provide guidance for the layout and water depth of the tank,the solidification behavior of ferrosilicon alloy droplet was numerically studied.A simplified model was established to elucidate the traveling trajectory and heat transfer of alloy droplet in air and cooling water during the atomization process.The solidification time of droplet with different thicknesses of solidification layer increased with the in crease in alloy droplet diameter.展开更多
Experimental and numerical investigations have been carried out on the effects of multi-swirl interaction patterns on self-excited unstable combustion characteristics based on a five-nozzle can combustor.The multi-swi...Experimental and numerical investigations have been carried out on the effects of multi-swirl interaction patterns on self-excited unstable combustion characteristics based on a five-nozzle can combustor.The multi-swirl interaction patterns include equal swirl intensity interaction and strong-weak swirl interaction.The thermo-acoustic instability characteristics indicate that increasing the central nozzle swirl intensity transforms the interaction pattern from equal swirl intensity interaction to strong-weak swirl interaction,which can significantly weaken the thermo-acoustic coupling effect under low equivalence ratio conditions,and substantially reduce the dynamic pressure amplitude during unstable combustion.The instantaneous flame structures show that the multi-swirl flames exhibit chaotic oscillations under low equivalence ratio conditions.With equivalence ratios greater than 0.71,a clear flame interaction boundary appears,and the flames can exhibit periodic oscillations in a regular structure.However,different interaction patterns result in the completely different phase oscillations in the central and outer flames.The time-averaged flame structures also indicate that strong-weak swirl interaction leads to an increase in the flame angle and a decrease in the flame length for both the central and outer flames,and the variations in the flame angle and length have great impacts on the thermo-acoustic instability mode.The fuel-staging combustion characteristics demonstrate that the instability combustion conditions with a dominant frequency of 100 Hz are greatly broadened by the strong-weak swirl interaction pattern,and the overlapping operating conditions between this mode and other modes are greatly increased.This implies that it is more flexible to adjust the thermo-acoustic unstable mode,which is conducive to the passive suppression of thermo-acoustic instability.展开更多
基金National Natural Science Foundation of China(Grant Nos.52275345,52175331)the Support plan for Outstanding Youth Innovation Team in Universities of Shandong Province,China(2021KJ044)Natural Science Foundation of Shandong Province,China(Granted No.ZR2020ZD04)。
文摘Electrohydrodynamic(EHD)jet printing represents a novel micro/nano-scale additive manufacturing process that utilises a high-voltage induced electric field between the nozzle and the substrate to print micro/nanoscale structures.EHD printing is particularly advantageous for the fabrication on flexible or non-flat substrates and of large aspect ratio micro/nanostructures and composite multi-material structures.Despite this,EHD printing has yet to be fully industrialised due to its low throughput,which is primarily caused by the limitations of serial additive printing technology.The parallel multi-nozzle array-based process has become the most promising option for EHD printing to achieve large-scale printing by increasing the number of nozzles to realise multichannel parallel printing.This paper reviews the recent development of multi-nozzle EHD printing technology,analyses jet motion with multi-nozzle,explains the origins of the electric field crosstalk effect under multi-nozzle and discusses several widely used methods for overcoming it.This work also summarises the impact of different process parameters on multi-nozzle EHD printing and describes the current manufacturing process using multi-nozzle as well as the method by which they can be realised independently.In addition,it presents an additional significant utilisation of multi-nozzle printing aside from enhancing single-nozzle production efficiency,which is the production of composite phase change materials through multi-nozzle.Finally,the future direction of multi-nozzle EHD printing development is discussed and envisioned.
文摘Based on the prototypes of a 130 t/h boiler, constant proportional cold-state test bench is established, flow characteristics of multi-nozzle in natural gas reburning burner and its influence on the covering effect for the upflow in the furnace are researched. Numerical simulations of this process are also made with standard ?turbulence model. The results show that air flow fullness in furnace is better in the case of the reburning zone with 8 nozzles compared to 4 nozzles and also coverage effect of the reburning flow for the updraft gas in the furnace is better. In the condition each nozzle airflow velocity is constant, the effect of reburning flow on coverage of up-secondary air is best when the incident angle for four corners is 14.17?, while Center of the furnace wall is 84.57. And while the best incident angle is invariable, the effect of reburning flow on coverage of up-secondary air is best when the speed of reburning gas in the corners of furnace is 51 m/s, the same to the center of the furnace wall’s.
基金co-supported by the National Level Project,China and Shanghai Municipal Major Science and Technology Project,China.In addition,the authors gratefully acknowledge the guidance on English writing and numerical methods of Professor Junfeng ZHANG from the Faculty of Engineering at Laurentian University.
文摘During the supersonic re-entry of multi-nozzle heavy rockets into the atmosphere,the basic flow state becomes increasingly complex due to the coupling effect between the retropropulsion plumes and the freestream.A numerical method using the hybrid Reynolds-Averaged Navier-Stokes and Large Eddy Simulation(RES)method and discrete coordinate method is developed to accurately estimate the thermal environment.In addition,finite rate chemical kinetics is used to calculate the afterburning reactions.The numerical results agree well with wind tunnel data,which confirms the validity and accuracy of the numerical method.Computations are conducted for the heavy carrier rocket re-entry from 53.1 km to 39.5 km altitude with 180°angle of attack by using three different Supersonic Retro-Propulsion(SRP)modes.The numerical results reveal that these three SRP flow fields are all Short Penetration Models(SPM).As the re-entry altitudes decrease,both the plume-plume interaction and the plume-freestream interaction become weaker.The highest temperatures in the plume shear layers of the three SRP modes increase by 8.36%,7.33%and 6.92%respectively after considering afterburning reactions,and all occur at a reentry altitude of 39.5 km.As the rocket re-enters the atmosphere,the maximum heat flux on the rocket base plate of three SRP modes stabilizes at 290,170 and 200 kW/m^(2) respectively,but the maximum heat flux on the side wall increases significantly.When the altitude declines to 39.5 km,the extreme heat flux of the three modes increase by 84.16%,49.45%and 62.97%respectively compared to that at 53.1 km.
基金the financial support for this work provided by the National Key R&D Program of China‘Technologies and Integrated Application of Magnesite Waste Utilization for High-Valued Chemicals and Materials’(2020YFC1909303)。
文摘This study developed a numerical model to efficiently treat solid waste magnesium nitrate hydrate through multi-step chemical reactions.The model simulates two-phase flow,heat,and mass transfer processes in a pyrolysis furnace to improve the decomposition rate of magnesium nitrate.The performance of multi-nozzle and single-nozzle injection methods was evaluated,and the effects of primary and secondary nozzle flow ratios,velocity ratios,and secondary nozzle inclination angles on the decomposition rate were investigated.Results indicate that multi-nozzle injection has a higher conversion efficiency and decomposition rate than single-nozzle injection,with a 10.3%higher conversion rate under the design parameters.The decomposition rate is primarily dependent on the average residence time of particles,which can be increased by decreasing flow rate and velocity ratios and increasing the inclination angle of secondary nozzles.The optimal parameters are injection flow ratio of 40%,injection velocity ratio of 0.6,and secondary nozzle inclination of 30°,corresponding to a maximum decomposition rate of 99.33%.
基金the National Natural Science Foundation of China(Grant No.2018YFC1900501)Graduate Scientific Research and Innovation Foundation of Chongqing(CYB19003).
文摘A novel granulation process that involved the use of a rotary multi-nozzles cup atomizer and water cooling was proposed for ferroalloy manufacturing.The effects of rotating speed and nozzle diameter on the properties of FeSi75 alloy(containing 75 wt.%Si)granules were investigated.Results indicated that median granule diameter decreased as rotating speed in creased,and initially increased and then decreased as nozzle diameter in creased.The optimal conditi ons for the gra nulation of FeSi75 alloy were a rotating speed of 150 r/min and nozzle diameter of 10 or 12 mm.The phase composition,micromorphology,and elemental distribution of the FeSi75 alloy granules were also studied by X-ray diffraction,scanning electron microscopy,and energy-dispersive X-ray spectrometry.In order to provide guidance for the layout and water depth of the tank,the solidification behavior of ferrosilicon alloy droplet was numerically studied.A simplified model was established to elucidate the traveling trajectory and heat transfer of alloy droplet in air and cooling water during the atomization process.The solidification time of droplet with different thicknesses of solidification layer increased with the in crease in alloy droplet diameter.
基金the National Science and Technology Major Project(HT-J2019-II-0018-0039)of China for financial support。
文摘Experimental and numerical investigations have been carried out on the effects of multi-swirl interaction patterns on self-excited unstable combustion characteristics based on a five-nozzle can combustor.The multi-swirl interaction patterns include equal swirl intensity interaction and strong-weak swirl interaction.The thermo-acoustic instability characteristics indicate that increasing the central nozzle swirl intensity transforms the interaction pattern from equal swirl intensity interaction to strong-weak swirl interaction,which can significantly weaken the thermo-acoustic coupling effect under low equivalence ratio conditions,and substantially reduce the dynamic pressure amplitude during unstable combustion.The instantaneous flame structures show that the multi-swirl flames exhibit chaotic oscillations under low equivalence ratio conditions.With equivalence ratios greater than 0.71,a clear flame interaction boundary appears,and the flames can exhibit periodic oscillations in a regular structure.However,different interaction patterns result in the completely different phase oscillations in the central and outer flames.The time-averaged flame structures also indicate that strong-weak swirl interaction leads to an increase in the flame angle and a decrease in the flame length for both the central and outer flames,and the variations in the flame angle and length have great impacts on the thermo-acoustic instability mode.The fuel-staging combustion characteristics demonstrate that the instability combustion conditions with a dominant frequency of 100 Hz are greatly broadened by the strong-weak swirl interaction pattern,and the overlapping operating conditions between this mode and other modes are greatly increased.This implies that it is more flexible to adjust the thermo-acoustic unstable mode,which is conducive to the passive suppression of thermo-acoustic instability.
