Pulsating modes of a Taylor cone under an unsteady electric field

2022 ◽  
Vol 34 (1) ◽  
pp. 012007
Author(s):  
Jin-bo Cheng ◽  
Li-jun Yang ◽  
Qing-fei Fu ◽  
Jun-xue Ren ◽  
Hai-bin Tang ◽  
...  
Keyword(s):  
Electric Field ◽  
Taylor Cone

scholarly journals Secondary Breakup Characteristics and Mechanism of Single Electrified Al/N-Decane Nanofluid Fuel Droplet in Electrostatic Field

2020 ◽  
Vol 10 (15) ◽  
pp. 5332
Author(s):  
Heng Lu ◽  
Shengji Li ◽  
Hongzhe Du ◽  
Yibin Lu ◽  
Xuefeng Huang
Keyword(s):  
Electric Field ◽  
Surface Charge ◽  
Electrostatic Field ◽  
Taylor Cone ◽  
Nanoparticle Concentration ◽  
Fuel Droplets ◽  
Electric Field Direction ◽  
Cone Formation ◽  
Nanofluid Fuel ◽  
Secondary Breakup

The combustion characteristics of nanofluid fuels have been widely investigated, but rare studies on the atomization were reported. Atomization is an imperative and crucial step to improve the combustion performance of nanofluid fuels, and the secondary breakup of droplets is an important segment for atomization to produce uniform fine droplets and distribute nanoparticles in each droplet. This paper firstly presents the secondary breakup characteristics of single electrified Al/n-decane nanofluid fuel droplets and revealed the mechanism of the secondary breakup. The results demonstrated that fine droplets could be produced in the electrostatic field and Al nanoparticles were distributed in each droplet. Before the breakup, the single electrified droplets experienced surface charge transportation, deformation, and Taylor cone formation. A gradient of the electric field deformed the droplet to produce the Taylor cone. As the Taylor cones were stabilized, the fluid was extruded from the tips of stable Taylor cones to produce jet filament parallel to the electric field direction and correspondingly broke up into fine sub droplets. At the nanoparticle concentration range of 1.0~10 mg/mL, the minimum average diameter of breakup sub droplets could achieve ~55.4 μm at 6.0 mg/mL. The Al nanoparticle concentration had a significant effect on the breakup performance by influencing the physical properties and charging. The order of the Charge-to-Mass ratio magnitude was 10−7~10−5 C/kg. Furthermore, the secondary breakup mechanism of single electrified nanofluid fuel droplets in the uniform electrostatic field was revealed by analyzing the droplet surface charge, deformation, Taylor cone formation, and nanoparticle concentration effect.

Preparation of Microfibers with Multi-Hollow Structure by Co-Electrospinning

2011 ◽  
Vol 311-313 ◽  
pp. 536-539
Author(s):  
Wei Bao Zhu ◽  
Xiao Chao Zhang ◽  
Yan Ping Wang ◽  
Yi Min Wang
Keyword(s):  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
Electric Field ◽  
Polymer Solution ◽  
Cross Section ◽  
High Voltage ◽  
Hollow Structure ◽  
Taylor Cone ◽  
Major Parameter ◽  
Scanning Electron

Co-electrospinning has been one of the most important and viable methods to prepare microfibers with hollow structure. In the process of co-electrospinning, microfibers were formed from polymer solution or melt by the action of high voltage electric field. In this article, the compound Taylor cone, a major parameter determining success or failure to prepare the hollow microfibers, was studied and the patterns of compound cone were summarized. The microfibers with single, double and triplicate holes in the cross-section were fabricated successfully under the guide of these patterns. The morphology of hollow microfibers was observed by scanning electron microscope (SEM).

Ion evaporation from Taylor cones of propylene carbonate mixed with ionic liquids

2007 ◽  
Vol 591 ◽  
pp. 437-459 ◽  
Author(s):  
I. GUERRERO ◽  
R. BOCANEGRA ◽  
F. J. HIGUERA ◽  
J. FERNANDEZ DE LA MORA
Keyword(s):  
Ionic Liquids ◽  
Electric Field ◽  
Electric Fields ◽  
Propylene Carbonate ◽  
Scaling Laws ◽  
Numerical Approach ◽  
Taylor Cone ◽  
Ion Current ◽  
Ion Currents ◽  
Ion Evaporation

A combined experimental and numerical approach is used to extract information on the kinetics of ion evaporation from the region of high electric field around the tip of a Taylor cone of the neutral solvent propylene carbonate (PC) mixed with two ionic liquids. On the numerical side, the electric field on the surface of the liquid is computed in the absence of evaporation by solving the electrohydrodynamic problem in this region within the framework of the leaky dielectric model. These computations justify the approximate (2% max error) scaling Emax = β Ek for the maximum electric field on the surface, with Ek = γ1/2 ϵ0−2/3 (K/Q)1/6 for 0.111 < K < 0.888 S m−1 and a numerical value of β ≈ 0.76. Here γ is the surface tension of PC, ϵ0 is the electrical permittivity of vacuum, and K and Q are the liquid electrical conductivity and flow rate. On the experimental side, 16 different propylene carbonate solutions with either of the ionic liquids 1-ethyl-3-methylimidazolium tetrafluoroborate (EMI-BF4) or EMI-bis(trifluoro-methylsulfonyl)imide (EMI-Im) are electrosprayed in a vacuum from a single Taylor cone, and their emissions of charged drops and ions are analysed by time-of-flight mass spectrometry at varying liquid flow rates Q. The sprays contain exclusively drops at large Q, both for small and for large electrical conductivities K, but enter a mixed ion–drop regime at sufficiently large K and small Q. Interestingly, the mixtures containing 10% and 15% (vol) EMI-Im exhibit no measurable ion currents at high Q, but approach a purely ionic regime (almost no drops) at small Q. The charge/mass ratio for the drops produced in these two mixtures increases continuously with decreasing Q, and gets very close to ionic values. Measured ion currents are represented versus computed maximum electric fields Emax on the liquid surface to infer ion evaporation kinetics. Comparison of measured ion currents with predictions from ion evaporation theory yields an anomalously low activation energy (~1.1 eV). This paradox appears to be due to alteration of the pure conj–eet electric field in the scaling laws used for the pure cone–jet regime, due to the substantial ion current density arising even when the ion current is relatively small. Elimination of this interference would require future ion current measurements in the 10–100 pA level. The electrical propulsion characteristics of the emissions from these liquids are determined and found to be excellent, particularly for 10% and 15% (vol) EMI-Im.

Numerical Study of Taylor Cone Dynamics in Electrospinning of Nanofibers

2017 ◽  
Vol 730 ◽  
pp. 510-515 ◽  
Author(s):  
Hui Fen Guo ◽  
Bin Gang Xu
Keyword(s):  
Electric Field ◽  
Numerical Study ◽  
Surface Force ◽  
Electrospinning Process ◽  
Numerical Results ◽  
Taylor Cone ◽  
Two Phase ◽  
Two Fluids ◽  
Vof Model ◽  
Electric Field Force

Nanofibers produced by electrospinning are attractive for a large variety of applications in material science. Formation of Taylor cone is an integral part of electrospinning process. To understand deeply its formation, a two-phase electro-hydrodynamic simulation under the volume-of-fluid (VOF) model is proposed. The electric force in such systems acts only at the interface and is zero elsewhere in the two fluids. Continuum surface force (CSF) model is adopted to compute the electric field force at the interface. For the study case, transient analyses showed the moving flow fronts and their interactions with the applied electric field. Two symmetric vortices, which occur in Taylor cone, will increase the solution velocity. A beaded nanofiber can be formed owing to the beads occur in cone jet. The numerical results were consistent with previous studies. According to the numerical results, the formation mechanism and nanofiber dynamics of the Taylor cone in a multiphase flow were well disclosed for deep explanation of the process.

Resolution in photoelectron microscopy

1991 ◽  
Vol 49 ◽  
pp. 458-459
Author(s):  
G. F. Rempfer
Keyword(s):  
Electron Microscopy ◽  
Electric Field ◽  
Ultraviolet Light ◽  
Uniform Field ◽  
Virtual Image ◽  
Lens System ◽  
Photoemission Electron Microscopy ◽  
Planar Electrode ◽  
Electron Lens ◽  
Photoemission Electron

In photoelectron microscopy (PEM), also called photoemission electron microscopy (PEEM), the image is formed by electrons which have been liberated from the specimen by ultraviolet light. The electrons are accelerated by an electric field before being imaged by an electron lens system. The specimen is supported on a planar electrode (or the electrode itself may be the specimen), and the accelerating field is applied between the specimen, which serves as the cathode, and an anode. The accelerating field is essentially uniform except for microfields near the surface of the specimen and a diverging field near the anode aperture. The uniform field forms a virtual image of the specimen (virtual specimen) at unit lateral magnification, approximately twice as far from the anode as is the specimen. The diverging field at the anode aperture in turn forms a virtual image of the virtual specimen at magnification 2/3, at a distance from the anode of 4/3 the specimen distance. This demagnified virtual image is the object for the objective stage of the lens system.

Field-assisted ionization theory for microscopists

1994 ◽  
Vol 52 ◽  
pp. 820-821
Author(s):  
Patrick P. Camus
Keyword(s):  
Electric Field ◽  
Electron Tunneling ◽  
Ionization Probability ◽  
Critical Distance ◽  
Tunneling Probability ◽  
Field Ionization ◽  
Radius Of Curvature ◽  
Field Evaporation ◽  
A Value ◽  
Ion Emission

The theory of field ion emission is the study of electron tunneling probability enhanced by the application of a high electric field. At subnanometer distances and kilovolt potentials, the probability of tunneling of electrons increases markedly. Field ionization of gas atoms produce atomic resolution images of the surface of the specimen, while field evaporation of surface atoms sections the specimen. Details of emission theory may be found in monographs.Field ionization (FI) is the phenomena whereby an electric field assists in the ionization of gas atoms via tunneling. The tunneling probability is a maximum at a critical distance above the surface,xc, Fig. 1. Energy is required to ionize the gas atom at xc, I, but at a value reduced by the appliedelectric field, xcFe, while energy is recovered by placing the electron in the specimen, φ. The highest ionization probability occurs for those regions on the specimen that have the highest local electric field. Those atoms which protrude from the average surfacehave the smallest radius of curvature, the highest field and therefore produce the highest ionizationprobability and brightest spots on the imaging screen, Fig. 2. This technique is called field ion microscopy (FIM).

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