| Electrospray based on the phenomenon of electrohydrodynamics is a simple and easily controlled atomization technology.It has the unique advantage of obtaining a large number of micron/nano-scale droplets with ultra-low energy consumption,which can significantly improve the atomization performance of liquids and enhance the heat and mass transfer efficiency of multiphase flow,and its application value in the fields of micro/nanoparticle or film preparation,biopharmaceuticals,micro-combustion,spray cooling,space micro-power propulsion,etc.is increasingly prominent.Most of the research on electrospray focuses on the so-called cone jet mode.However,in order to obtain micron/nano-scale droplets with good monodispersity through stable cone jet atomization,it is necessary to control the supply flow rate at a very small level,which cannot meet the actual needs of many industrial applications.Stable multi-jets and its array integrated atomization are effective ways to break through the flow bottleneck of electrospray,however,the involved morphology and jet number evolution behavior of stable multi-jets,stable atomization operation range,jet characteristics in stable multijet mode,spray droplet size,and the atomization characteristics of array integrated stable multi-jets under the voltage edge effect are not clear yet,which has important research value.In this thesis,experimental research on the electrohydrodynamic atomization characteristics of stable multi-jets and its array integration was carried out,the main research work and innovations are as follows:Investigation on the evolution behavior of the jet structure and jet characteristics in stable multi-jet mode.The microscopic morphology characteristics of the stable multijets structure evolving with the number of jets were accurately recorded by high-speed photography technique.The operating domain of different jet modes was defined by using the electric Weber number EWe and the electric Bond number EBo.The distribution characteristics of the number of stable jets were obtained.The voltage switching phenomenon in the stable multi-jet mode was found.The structural characteristics of the stable multi-jets were described by the characterization variables,which provides an important reference for the configuration design of the stable multijets array integrated device.Investigation on the electrohydrodynamic atomization characteristics of stable multi-jets.The size information of spray droplets formed by the atomization of stable multi-jets was recorded in real-time using a high-speed spray particle size analyzer,and the relevant statistical data for evaluating the spray performance was processed and analyzed.The effects of electric Weber number and electric Bond number on the average size of droplets and the characteristics of droplet size distribution were discussed,and the uniformity of spray droplet size under the stable multi-jet mode was analyzed.The results provide an experimental basis for the analysis of the atomization characteristics of the array integrated stable multi-jets.Investigation on the electrohydrodynamic atomization characteristics of the array integrated stable multi-jets.Designed and constructed an array integrated microchannel electrohydrodynamic atomization system,and proposed adding a double-layer cross space shielding electrode as a method to solve the voltage edge effect.The evolution characteristics of jet morphology of the array integrated stable multi-jets atomization were accurately recorded.The stable operating voltage range of devices with different integration levels was discussed,and the effects of supply flow rate and integration level on the average size of spray droplets and the droplet size distribution were analyzed.The critical control parameters for the stable operation of multi-jets under the array integrated device were determined,which provides a reference for the design of the array integrated microchannel electrohydrodynamic atomization device with higher integration density. |
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