Increase Of Electric Field Intensity Research Articles

Stable multi-jet behavior of ethanol under an electric field

Electrospray is a mass transfer technology in which charged liquid is broken into fine droplets/particles with ideal monodispersity, easy controllability, and high-deposition . In recent decades, with the rapid development of various micro precision instrument technologies, the research of electrospray has been widely applied to micro/nano-scaled thin film and particle preparation, air purification, micro-combustion, space micro-propulsion, mass spectrometry, and biotechnology. Previous researches mainly focused on the stable cone-jet mode that has the advantages for producing several micron-sized particles or droplets with good stability and monodispersity. However, electrospray in this cone-jet mode has a major disadvantage that restricts the practical application of electrospray. The droplet size in the cone-jet mode increases with an increase of the flow rate, and this means the production of tiny droplets limits the supply flow rate, and this limited flow rate cannot meet the requirements for atomization flow in practical application. Multi-jet is an important operation mode in electrospray, and sub-droplets of comparable size to the sub-droplets produced by cone-jet can be obtained on the basis of multiplication of the single capillary flow. However, multi-jet atomization is very unstable, and it is difficult to attain a stable jet atomization state; therefore, in-depth research on the evolution of its morphology and atomization characteristics is necessary to expand the practical application of electrostatic atomization technology. Based on high-speed photography technology with a high spatial-temporal resolution, the influence of capillary geometry, electrode spacing, liquid supply flow rate, and applied voltage on the multi-jet formation and evolution in electrospray was studied in detail. The electric bond number and the dimensionless flow rate were introduced to describe their action laws on the evolution behavior of the stable jet number, stable atomization range, and jet deviation angle in the stable multi-jet mode. The research results show that the range of the number of stable jets N of multi-jet is from 2 to 10. When 2≤ N N ≤10, the jets are ejected from the outer edge of the capillary orifice to form an edge jet mode, and it is particularly important to note that the occurrence frequency of the stable 5–8 strands is higher than other strands. In the edge mode, as the number of stable jets increases, the range of the electric bond number of the stable multi-jets and the critical minimum electric bond number gradually increases, and a voltage switching phenomenon of stabilizing multi-jet is also presented. As the dimensionless flow rate increases, the maximum value of the electric bond number under each number of stable jets shows a linear growth trend. The maximum value of the electric bond number increases with the increase of the stable jet number under the same flow rate, and a significant increase in the minimum value of the electric bond number is observed. Additionally, as the number of stable jets in the edge mode increases, the overall deviation angle of the jet increases, but the range of variation of the deviation angle of each stable jet number is controlled within 5°±0.3°. Moreover, as the electric bond number increases, the jet deviation angle gets closer to 45°, which indicates that the electric field force dominates the jet deviation as the electric field intensity increases.

Nonlinear Switching Transient Field Simulation of Cable Joint without Residual Charge

The analysis of the impulse voltage on the internal electric field of the cable joint plays a key role in studying the breakdown of the joint. Based on the finite element method, a three-dimensional electromagnetic field simulation model of the cable joint is established in this paper. Simulation results show that the voltage at the head of the cable joint reaches about twice the impulse voltage. The increase of the conductivity of semi-conductive material also leads to the increase of electric field intensity. Then, several points and curves at different positions are selected for further analysis in this paper. Among them, the electric field distortion at the edge of the high voltage shield is the most serious and the electric field in the air gap is the least.

Dissipative particle dynamics simulations of centrifugal melt electrospinning

The fibers obtained by centrifugal melt electrospinning exhibit high production efficiency, controllable morphology, and excellent mechanical properties. Therefore, centrifugal electrospinning technology is in alignment with the industrial development trend of superfine fiber preparation. However, during the rapid development of this new spin method, some fundamental understanding of the relationships between the fiber performance and centrifugal force, electric field force, and gravity is unclear. In this study, the effect of the spin factors on the fiber properties (diameter, yield, and molecular chain formation) is investigated by dissipative particle dynamics simulation. The results show that in an electrostatic field, if the rotating speed, temperature, and electric field intensity increases, the fiber diameter decreases, and fiber productivity and chain length increase. In a pulsed electric field, the fiber diameter is very small when the duty ratio is 70% and the chain length is long when the duty ratio is 100%. However, as the frequency increases, the fiber diameter decreases sharply, whereas the chain length increases gradually. When the fiber drops rapidly, the chain length generally becomes longer with increasing steps. The above knowledge of the fiber performance and spin factors will contribute significantly to obtain high-quality fibers using centrifugal melt electrospinning.

The Suppression of transformation of γ-FeOOH to α-FeOOH accelerating the steel corrosion in simulated industrial atmospheric environment with a DC electric field interference

ABSTRACTThe initial corrosion of steels exposed to the simulated industrial atmospheric environment with a direct current (DC) electric field for 30 days was investigated using weight loss, electrochemical and characterisation methods. The results show that the steel weight loss increased with the increase in DC electric field intensity. The steels exposed to the DC electric field interference exhibited a higher corrosion rate than the blank samples during the exposure. The microstructural studies reveal that the existence of the DC electric field favours the growth of the γ-FeOOH, while suppresses the transformation of γ-FeOOH into α-FeOOH during the 30 days’ exposure, as a result of decreasing the protective ability and stable property of the rust layer. The amount of porous γ-FeOOH enhances the transmission of oxygen and conductivity of the whole rust layer. All these induce an accelerated effect of DC electric field on the initial steel corrosion in simulated industrial environment.

Dynamic Behavior of Droplets and Flashover Characteristics for CFD and Experimental Analysis on SiR Composites

The dynamic mechanism of water droplet formation has recently drawn considerable attention in research and application toward silicon rubber composite insulators. This paper is aimed at numerical simulations and experiments on the dynamic mechanism of water droplet formation with different applied voltages and droplet distribution and induced surface discharges on the insulator surface under the impact of AC electric field. The computational fluid dynamics model and experimental setup of multiple droplets were established to analyze the dynamic behavior of droplets and flashover characteristics. The obtained results reveal that the fusion first occurs between larger size droplets and the fusion is hard to happen along with the rise of the fractal dimension (FD) of droplet distribution. The elongation of droplets merges with more droplets and finally affects the electric field distribution on the insulator surface. With the increase of FD, the maximum electric field intensity shows an increasing tendency. Meanwhile, the experimental results show that with the increase of electric field intensity, the droplet fusion phenomenon becomes more obvious, which is consistent with the simulation results. The flashover voltage on the surface of silicon rubber decreases with the decrease of the FD of droplets, indicating that the complexity of droplet distribution has a significant effect on the flashover voltage.

Spectrum and dissociation properties of fluoro trichloro methane molecule in radiational field

The ozone layer in the stratosphere of the earth’s atmosphere, which can be destroyed by CFC-11 molecule, plays a crucial role in human survival because it can absorb most of the harmful radiation from the sun and effectively protect the earth’s biology. Therefore, it is of evident significance to investigate the properties of CFC-11 molecule. By Motivated by this and the adoption of B3LYP complex function at a level of 6-311++g(3df, 3pd) basis set, we carry out a series of theoretical studies of the Freon material CFC-11 (CFCl3) molecules, including the studies of the equilibrium structure, electric dipole moment, total energy, the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) level, energy gap, infrared and Raman spectrum, C—F dissociation characteristics of CFC-11 molecule, and the effect of the applied electric field on CFC-11 molecule as well. The results show that the maximum error between the theoretical calculation value and the experimental value is less than 2% for an optimized ground state structure; the C—F bond length and C—Cl bond length extend with the increase of electric field intensity, but the degree of change of C—F bond length is much stronger than that of C—Cl; the HOMO energy level and total energy go up and then come down as the external field rises, while the LUMO energy level goes up as the field increases. The energy gap <i>E</i><sub>g</sub> first increases and then decreases with the variation of <i>E</i><sub>H</sub> and <i>E</i><sub>L</sub>. The dipole moment without electric field is a minimum value, and the external electric field leads the molecular polarity to increase and the molecular activity to strengthen. The electric field influences the absorption intensity of infrared and Raman spectrum. The infrared and Raman spectrum move toward the long wave under the action of positive electric field, while they move toward the short wave under the action of negative electric field. The red- or blue-shift of infrared and Raman spectrum occur with the change of electric field. The electric field can be adopted as an auxiliary means to separate the overlapping or quasi-overlapping spectral lines. The potential well depth decreases with the increase of the reverse electric field until it vanishes, which causes the bound state ability of C—F bond of CFC-11 molecule to gradually degrade. This paper is expected to provide a feasible and effective tunable means for the final dissociation and degradation of CFC-11 molecules.

Vibration of two-dimensional hexagonal boron nitride

ABSTRACT The dynamic behavior of two-dimensional nanostructures is important to the future application of nano devices. The vibrational behaviors of single-layered hexagonal boron nitride (h-BN) are studied by molecular dynamics simulation and continuum plate model. The bending stiffness and Poisson's ratios of h-BN along zigzag direction and armchair direction are calculated. H-BN is softer compared with graphene. The continuum plate model can predict the vibration of h-BN with four edge-clamped boundary conditions well. The electric fields in different directions have obvious influence on the vibration of h-BN. The natural frequency of h-BN changes linearly with the electric field intensity along the polarization direction. The natural frequency of h-BN decreases with the increase of electric field intensity along both positive and negative non-polarization direction. While the natural frequency of h-BN increases with the increase of electric field intensity along both positive and negative transverse electric field.

Natural convection heat transfer of nanofluid in a cavity under an inhomogeneous electric field

Natural convective heat transfer of nanofluid consisted of transformer oil and Al2O3 nanoparticles in a cavity under a non-uniform high electric field intensity was experimental investigated. The main objective is looking for a coupling enhanced method by nanofluid and electric field. It is found that when the effect of gravity is ignored, the electric field forces applied on the working fluids induce an electric convection and thence induce significant heat transfer enhancement. This enhancement effect increases rapidly with the increase of electric field intensity, the nanoparticles mass concentration of nanofluid and the heat flux. When the effect of gravity exists, a coupled convection is caused by both gravity and electric field force together. For pure transformer oil, the influences of electric field force and gravity on the heat transfer almost offset each other. However, for nanofluid, the impact of the electric filed force is dominant. The study results revealed the enhanced mechanism of natural convection heat transfer of nanofluid under electric field and provided some useful technical support for practical application.

Effects of electrolyte thickness, chloride ion concentration, and an external direct current electric field on corrosion behaviour of silver under a thin electrolyte layer

ABSTRACTEffects of electrolyte thickness, chloride ion concentration, and an external direct current electric field (DCEF) on the corrosion behaviour of silver under a thin electrolyte layer (TEL) were investigated using electrochemical and surface techniques. The results indicate the corrosion rate of silver increases with the decrease of TEL thickness and the increase of chloride ion concentration. Moreover, an interesting conclusion was drawn that the corrosion rate of silver near the positive plate of DCEF first increases and then decreases with the increase of electric field intensity. In a DCEF, different polarisation behaviours of silver at different positions were attributed to the differences of the local corrosion environment.

Influence of electric field on the viscosity of waxy crude oil and micro property of paraffin: A molecular dynamics simulation study

Electrical treatment is a useful method for reducing viscosity of waxy crude oil. Molecular dynamics simulation was employed to study the influence of electric field on viscosity of waxy crude oil and micro properties of paraffin. The waxy crude oil model consists of light oil and 24.9% by weight of paraffin. The simulation results show that viscosity decreases when electric field is applied. The larger the electric field intensity, the greater the decreasing extent of viscosity. The electrical viscosity-reducing effect is better at lower temperatures. The radial distribution function and diffusion coefficient were analyzed for explaining the reason of viscosity decreasing. The radial distribution function results confirm that electric field promotes aggregation of paraffin molecules. Diffusion coefficient increases with the increase of electric field intensity. At the same temperature, the higher the electric field strength, the larger the increasing extent of diffusion coefficient. In a certain electric field intensity, the lower the temperature, the greater the increasing extent. The changing tendency of diffusion coefficient is consistent with the trend of viscosity reduction under electrical treatment. It is suggested that the change of diffusion coefficient is the main reason for electrical viscosity-reducing effects, the contribution of aggregation is smaller than increasing of diffusion coefficient.

Enhanced extraction of phenolic compounds from onion by pulsed electric field (PEF)

The extraction of water-soluble phenolic compounds from onion assisted by pulsed electric field treatment (PEF) was investigated as well as the antioxidant activity of the extracts. Results indicated that the yield of water-soluble phenolic compounds (PC) and flavonoid compounds (FC) from onion was significantly increased after treated by PEF treatment following water extraction. Meanwhile, the antioxidant activity of extracts increased with the increase in electric field intensity and treatment time. Box–Behnken design was employed to optimize the extraction process. The optimal conditions were 2.5 kV/cm, 90 pulses and 45°C for both of PC and FC. Under those conditions, the content of PC and FC in extracts was 102.86 mg GAE 100 g–1 FW and 37.58 mg QE 100 g–1 FW, increased by 2.2 and 2.7 times, respectively, in comparison to control (Non-PEF treatment) (PC is 32.13 GAE 100 g–1 FW，FC is 10.22 mg QE 100 g–1 FW). Although the extraction yields of PC and FC for PEF-assisted aqueous extraction was just 1/3 and 1/2 of soxhlet extraction, compared to conventional extraction methods with toxic, organic solvent, PEF-assisted aqueous extraction method is a selective, environmental friend process to recover water-soluble PC and FC from onion. Practical application Onion is abundant of phenolic compounds, particularly flavonols which are considered to be a reduced risk of many diseases by inhibition of lipid peroxidation. PEF processing as a non-thermal technology for preservation of liquid foods has been investigated extensively during the last decades without destroying original sensorial and nutritional properties of food. In this study, it demonstrated that as efficient cell wall disruption technique, the aqueous extraction of phenolic compounds (PC) and flavonoid compounds (FC) from onion was facilitated significantly by PEF treatment. Therefore, PEF-assisted aqueous extraction method has great potential as a selective, environmental friend process to recover water-soluble PC and FC from onion.

Adsorption of lithium polysulfides on an anatase (1 0 1) and an [formula omitted]-Al2O3 (0 0 0 1) surface under external electric field with first principles calculations

The “shuttle effect” induced by the dissolution and diffusion of the Li2Sx (4⩽x⩽8) into the electrolyte is a crucial problem of a LiS battery. Anatase or Al2O3 can be used as an additive to suppress the “shuttle effect”. First-principles approach coupled with van der Waals (vdW) interaction is used to calculate the adsorption energies of Li2Sx (x=4,6,8) molecules on an anatase (1 0 1) or an α-Al2O3 (0 0 0 1) surface. The results show that the adsorption of the molecules on an α-Al2O3 (0 0 0 1) is stronger than that on an anatase (1 0 1) surface. Furthermore, owing to the existence of an electric field inside the battery during the charge-discharge process, the external electric field effects on the adsorption are investigated. As a result, the adsorption energy (absolute value) almost linearly increases with the increase of electric field intensity in the range from -0.16 to 0.16 V/Å. In addition, the responses of different Li2Sx molecules on an anatase (1 0 1) surface or an α-Al2O3 (0 0 0 1) surface to the external electric fields are different.

Joint effect of electric and magnetic field on electron energy spectrum in spherical nanostructure ZnS/CdSe/ZnS

The electron energy spectrum in inverted core-shell quantum dot driven by magnetic and electric fields is studied. The parallel and perpendicular electric and magnetic fields are considered. The Schödinger equation is solved using the method of expansion of the electron wave function on the basis of wave functions in the nanostructure without the external fields.The formation of the electron ground state under the influence of the electric and magnetic field is researched. It is shown that this state is successively formed by the states with m ≤ 0 (Aharonov-Bohm effect) when the magnetic field induction increases. This effect vanishes when the electric field intensity increases and if the magnetic field is parallel to the electric one. The electron ground state is characterized only by quantum number m = 0 in the whole range of magnetic field induction when the electric field intensity is bigger than certain critical magnitude. When the electric field intensity increases, being perpendicular to the magnetic one, the cylindrical symmetry of problem is broken and the wave function of electron ground state is obtained as a series, containing the states with different values of magnetic quantum number. Their partial contributions essentially depend on the magnitudes of electric field intensity and magnetic field induction. The effect of magnetic field on electron ground state energy decreases when the external fields are perpendicular.The peculiarities of the formation of electron energy spectrum due to the electric and magnetic field should be displayed on the selection rules and the energies of quantum transitions and, thus, on the optical properties of nanostructure.

Electrically tuned whispering gallery modes microresonator based on microstructured optical fibers infiltrated with dual-frequency liquid crystals

Abstract An electrically tunable whispering gallery mode (WGM) microresonator based on an HF-etched microstructured optical fiber (MOF) infiltrated with dual-frequency liquid crystals (DFLCs) is proposed and experimentally demonstrated for the investigation of the crossover frequency and Freedericksz transition of DFLCs. Experimental results indicate that for applied electric field with operation frequency below the crossover frequency, WGM resonance wavelength decreases with the increment of applied electric field strength. On the contrary, for applied electric field with operation frequency beyond the crossover frequency, WGM resonance dips show red shift as the applied electric field intensity increases. The proposed electrically tunable microcavity integrated with DFLCs is anticipated to find potential applications in optical filtering, all-optical switching, and electrically manipulated bi-directional micro-optics devices.

Simulation study of the performance of new micropattern gaseous detectors

The micropattern gaseous detectors (MPGDs) are widely used in high-energy physics experiment, such as detector upgrade projects in LHC, due to its excellent performance on rate capability, spatial and time resolutions. In this paper, we studied the performances of GEM, FTM and $$\mu $$ -RWELL detectors on time and spatial resolutions using Monte Carlo simulation methods and compared their performances and characteristics at various working conditions. Result shows that time resolution of MPGDs improves with the increase of electric field intensity in drift region, while spatial resolution shows the reverse tendency. In addition, detectors operating with an electronegative gas mixture show better performances on both time and spatial resolution. We studied the performance of triple-GEM, FTM and $$\mu $$ -RWELL detectors with Monte Carlo simulation. In this paper, ANSYS and GARFIELD are used to build full electric field model of the detector. The time resolution and spatial resolution are derived, which are very important for triggering performance and track reconstruction ability. These results will provide references on detector design and the technology chosen in LHC detector upgrade projects.

Electrothermal Convection in Dielectric Maxwellian Nanofluid Layer

The influence of rheological behavior on the natural convection in a dielectric nanofluid with vertical AC electric field is investigated. The rheology of the nanofluid is described by Maxwell model for calculating the shear stresses from the velocity gradients. The employed model introduces the combined effects of movement of the molecules of the fluid striking the nanoparticles, thermophoresis and electrophoresis due to embedded nanoparticles. The exact solutions of the eigen model value problem for stress-free bounding surfaces are obtained analytically using one term Galerkin method to find the thermal Rayleigh number for onset of both non-oscillatory (stationary) and oscillatory motions. It is found that the oscillatory modes are possible for both bottom and top-heavy distributions of nanoparticles. It is observed that the value of critical Rayleigh number is decreased by a substantial amount with the increase in electric field intensity, whereas role of viscoelasticity (time relaxation parameter) is to hasten the occurence of oscillatory modes appreciably. The thermal Prandtl number is found to delay the occurence of oscillatory modes. These results are also shown graphically.

Molecular structure and properties of salt cross-linked polyethylene under external electric field based on density functional theory

Cross-linked polyethylene is the main power cable insulation material and is widely used in high voltage cables. In order to study the effect of external electric field on the molecular structure of salt cross-linked polyethylene, in this paper we use the basis set of def2-TZVP for Zn atom, uses the basis set of 6-31(d) for C, H, O atoms, and uses the Minnesota density functional (M06-2X) to optimize the molecular structure of salt cross-linked polyethylene, then we obtain the stable structure of its ground state. On this basis, the molecular structure, total energy, kinetic energy, potential energy, dipole moment and polarizability changes of salt cross-linked polyethylene under the action of different external electric fields (from 0 to 0.020 a.u.) are studied by the same method. The influence of external electric field on energy level, energy gap, orbital distribution and composition of frontier orbit are studied. And the effect of external electric field on bond level, breaking bond and infrared spectrum of atoms are also discussed. The research results show that as the external electric field intensity increases, the cross-linked polyethylene molecule is gradually transformed from the spatial network structure into a linear structure, and the total energy and kinetic energy of the molecule are reduced, but its potential energy, dipole moment and polarizability are gradually increased. The highest occupied molecular orbital energy level increases with the increase of external electric field intensity. The lowest unoccupied molecular orbital energy level starts to decrease continuously from the electric field intensity of 0.011 a.u. (1 a.u. = 5:1421011 V/m), the energy gap decreases continuously, and the critical breakdown field intensity is 11.16 GV/m. With the external electric field increasing dramatically, the highest occupied molecular orbital is obviously converged at chain end in the direction of inverse electric field. Its orbital composition is more than 60%, contributed by the C atom of methyl group in the polyethylene terminal. The molecular polyethylene chain end of the inverse electric field direction exhibits an electrophilic reactivity, and C atoms are more likely to lose electrons. The Mayer bond order value of the CC bond decreases gradually, which leads the CC bonds to break more easily, and thus forming the methyl carbon negative ions. The lowest unoccupied molecular orbital moves along the electric field direction and is converged at the other end of polyethylene chain, nearly 80% of its orbital composition is contributed by the methyl of polyethylene chain end. The molecule shows a nucleophilic reactivity at the polyethylene end along the electric field direction, methyl is easier to obtain the electrons. The Mayer bond order value of the CH bond decreases gradually, and it brings about the CH bond more likely to break into H positive ions. The infrared absorption peaks of polyethylene chains are mainly concentrated in the high frequency region. With the increase of electric field intensity, the red shift occurs and the bond energy of polyethylene chain decreases. The infrared absorption peak of the cross-linked salt bridge is mainly concentrated in the low frequency area. Although there are both red shift and blue shift, the effect of red shift is more obvious, and the energy of the whole salt bridge decreases. From the variation of molecular potential energy, energy gap and Mayer bond order value, it is found that the stability of salt cross-linked polyethylene molecular system decreases with the increase of external electric field intensity.

Ultra-high voltage electron microscopy investigation of irradiation induced displacement defects on AlGaN/GaN HEMTs

Irradiation effects produced by high energy heavy ions and electrons on AlGaN/GaN high electron mobility transistor (HEMT) were investigated using ultra-high voltage electron microscopy (HVEM), optical measurements, and device characteristics analysis. The dislocation loop created on a thick (1.5μm) sample irradiated by 18MeV Ni ions was observed by HVEM. The distribution of the defects matched the calculated distribution obtained using the stopping and range of ions in matter (SRIM) code. In-situ dislocation loop generation was observed in the sample during a high energy (2MeV) electron irradiation by using HVEM. Device characteristics were found to remain stable, no increase in leakage current or electric field intensity being noticed up to a high radiant fluence of Ni and electron irradiation. These results demonstrate a high radiation tolerance of the device for space applications.

Triboluminescence modulated by humidity

Triboluminescence (TL) reflects the characteristics of real-time optical signals generated in the process of friction, hence is promising in real-time monitoring and surface study. By studying the sliding between SiO2 and Al2O3, we found that triboluminescence can be modulated quantitatively by modifying ambient humidity. The trend of TL intensity varies at different ranges of humidity and there exists a critical humidity. TL intensity rises initially and reaches its peak at critical humidity before it diminishes and eventually decreases to zero. It results from the decrease of energy barrier of tribo-charging and the increase of electric field intensity below critical humidity, and for humidity above critical humidity, the rapid growth of surface conductivity and a shorter distance account for smaller possibility of gas collision.

Effects of electric field on micro-scale flame properties of biobutanol fuel.

With the increasing need of smaller power sources for satellites, energy systems and engine equipment, microcombustion pose a potential as alternative power source to conventional batteries. As the substitute fuel source for gasoline, biobutanol shows more promising characteristics than ethanol. In this study, the diffusion microflame of liquid biobutanol under electric field have been examined through in-lab experiment and numerical simulation. It is found that traditional gas jet diffusion flame theory shows significant inconsistency with the experimental results of micro scale flame in electric field. The results suggest that with the increase of electric field intensity, the quenching flow rate decrease first and increase after it reach its minimum, while the flame height and highest flame temperature increase first and drop after its peak value. In addition, it was also observed that the flame height and highest temperature for smaller tube can reach its maximum faster. Therefore, the interaction between microscale effect and electric field plays a significant role on understanding the microcombustion of liquid fuel. Therefore, FLUENT simulation was adopted to understand and measure the impacts of microflame characteristic parameters. The final numerical results are consistent with the experimental data and show a high reliability.