PARAMETERS AFFECTING LAMELLAR FORMATIONS IN ER FLUIDS: AN ALTERNATIVE MODEL FOR ER ACTIVITY

2001 ◽  
Vol 15 (06n07) ◽  
pp. 686-694 ◽  
Author(s):  
F. E. FILISKO ◽  
S. HENLEY
Keyword(s):  
Electric Field ◽  
Alternative Model ◽  
Particle Concentration ◽  
Electrode Gap ◽  
Present Information ◽  
Complex Functions ◽  
Lamellar Texture ◽  
Chain Breaking ◽  
Static Conditions ◽  
Er Fluids

Under static conditions, ER suspensions form columns under electric field. However under the combined stimulii of a shear and electric field, the particles assemble into lamellar structures. The morphology of these structures are complex functions of electric field, shear rate, time of shear, electrode gap, particle concentration, and others. In this paper we present information regarding the field dependence, the concentration dependence, and the sequence of application of the electric and shear fields. A alternative model for ER activity, other than chain breaking, is presented which incorporates this lamellar texture.

Electrorheology of conducting polyaniline composite particles

e-Polymers ◽  
2004 ◽  
Vol 4 (1) ◽  
Author(s):  
Hyoung Jin Choi ◽  
Min Sung Cho ◽  
Young Hoon Lee ◽  
Yun Hyang Cho ◽  
Myung S. Jhon
Keyword(s):  
Electric Field ◽  
Applied Electric Field ◽  
Particle Concentration ◽  
Fast Response ◽  
Formaldehyde Resin ◽  
Rheological Characteristics ◽  
Melamine Formaldehyde ◽  
Applied Electric Field Strength ◽  
Shell System ◽  
Er Fluids

Abstract Three different kinds of particles of semiconductive polyaniline (PANI), spherical poly(methyl methacrylate) with a PANI shell (PAPMMA), and conductive PANI encapsulated by insulating melamine-formaldehyde resin (MCPA) were synthesized and adopted as a dispersed phase for electrorheological (ER) fluids. ER fluids are suspensions of polarizable particles dispersed in non-conducting liquids. The rheological characteristics of ER fluids rapidly change in the presence of an applied electric field, which can be controlled by both the applied electric field strength and particle concentration with a fast response time on the order of milliseconds. MCPA-based ER fluids show the largest stress enhancement by an applied electric field compared with both PANI- and PAPMMA-based ER fluids, demonstrating that the conductive core with an insulating shell system is a better ER material than homogeneous, semiconductive materials or surface-semiconductive materials with insulating cores.

Electrorheological Fluid Hysteresis

Materials ◽  
2005 ◽  
Author(s):  
Young Dae Kim ◽  
Daniel De Kee
Keyword(s):  
Shear Rate ◽  
Field Strength ◽  
Electric Field ◽  
Electric Field Strength ◽  
Particle Concentration ◽  
Electrorheological Fluid ◽  
Particle Structure ◽  
Hysteresis Behavior ◽  
Precise Control ◽  
Er Fluids

Electrorheological (ER) fluids are suspensions of polarizable particles dispersed in insulating liquids. They exhibit a rapid and reversible transition from a liquid-like to a solid-like state upon the application of an electric field. The observed shear stress - shear rate hysteresis makes the precise control of the ER mechanical devices very difficult. Hysteresis behavior of TiO2 ER fluids were observed by varying particle concentration, electric field strength, maximum shear rate, and the time of hysteresis loop. In the absence of an electric field, the stress level of the up curve exceeds that of the down curve. The presence of an electric field, reverses this trend. The extent of hysteresis becomes more significant with increasing electric field strength, particle concentration, and maximum shear rate. Hysteresis behavior of TiO2 ER fluids seems to arise mainly due to the change of the particle structure during shearing. To describe the complex rheological behavior of ER fluids, a kinetic theory is presented. Model predictions show qualitative agreement with the experimental hysteresis data.

PRELIMINARY OPTICAL STUDY ON ER FLUIDS

1994 ◽  
Vol 08 (20n21) ◽  
pp. 2921-2933 ◽  
Author(s):  
L. W. ZHOU ◽  
J. F. YE ◽  
R. B. TAO ◽  
Y. TANG ◽  
J. F. PENG ◽  
...  
Keyword(s):  
Phase Transition ◽  
Electric Field ◽  
Electric Fields ◽  
Nonlinear Optical ◽  
Second Harmonic ◽  
Optical Response ◽  
Optical Study ◽  
Solid States ◽  
Linear And Nonlinear ◽  
Er Fluids

Linear and nonlinear optical study on electrorheological (ER) fluids is reported. The ER fluids under the investigation were glass beads, zeolite and ferroelectrics. The linear optical response of some ER fluids showed sharp changes near critical electric fields. An enhancement of electric field induced second harmonic generations (EFISH) was observed as the function of E2, where E is the external electric field. The said enhancement is considered to be corresponding to a modulation of the material's refractive index associated with the electric field induced polarization of the delocalized electrons. The enhanced nonlinear optical response on the transition between liquid and solid states can be related to the phase transition in ER fluids.

scholarly journals Detection of oscillatory solutions in a vacuum diode with total electron reflection

2021 ◽  
Vol 2103 (1) ◽  
pp. 012205
Author(s):  
V I Kuznetsov ◽  
IK Morozov
Keyword(s):  
Electron Beam ◽  
Electric Field ◽  
Vacuum Diode ◽  
Boundary Line ◽  
Electrode Gap ◽  
Oscillatory Solutions ◽  
Total Electron ◽  
Electron Reflection ◽  
Instability Development ◽  
Non Linear

Abstract Stability features of steady-state solutions for a vacuum diode with complete deceleration of electron beam is studied. A boundary line on the (inter-electrode gap, external voltage)-plane separating stable solutions from unstable ones is built up. An instability development is shown to end in a state with non-linear oscillations of the electric field but with no virtual cathode in a plasma. Existence of non-linear oscillations of the electric field in a vacuum diode with total reflection of an electron beam points out that such a diode can be a basis to create microwave generator.

scholarly journals THE EFFECT OF ELECTRIC FIELD DIRECTION ON THE-SHEAR STRESS OF ER FLUIDS

1996 ◽  
Vol 45 (4) ◽  
pp. 640
Author(s):  
WANG ZUO-WEI ◽  
LIN ZHI-FANG ◽  
TAO RUI-BAO
Keyword(s):  
Shear Stress ◽  
Electric Field ◽  
Field Direction ◽  
Electric Field Direction ◽  
Er Fluids

MOLECULAR ORIENTATION AND ELECTROHYDRODYNAMIC FLOW IN HOMOGENEOUS ER FLUIDS

2001 ◽  
Vol 15 (06n07) ◽  
pp. 973-979 ◽  
Author(s):  
HIROKI IWATSUKI ◽  
NAOTO GOHKO ◽  
HIROSHI KIMURA ◽  
YUICHI MASUBUCHI ◽  
JUN-ICHI TAKIMOTO ◽  
...  
Keyword(s):  
Liquid Crystals ◽  
Electric Field ◽  
Molecular Orientation ◽  
Liquid Crystalline ◽  
Polypropylene Glycol ◽  
Homogeneous Fluid ◽  
Immiscible Liquids ◽  
Electrohydrodynamic Flow ◽  
Er Fluids ◽  
Er Fluid

Homogeneous ER fluid is an ER fluid which consists of a homogeneous fluid only; it is neither a suspension nor a blend of immiscible liquids. Various liquid crystals are typical examples of homogeneous ER fluids. Recently, we have found that urethane-modified polypropylene glycol (UPPG) is one of the very few examples of homogeneous ER fluids which show no liquid crystalline order. In order to clarify the mechanism of the ER effect in this fluid, we have studied, in this paper, electrohydrodynamic flow under shear and electric field.

scholarly journals Effects of Fiber and Copper Particles on Conductivity and Breakdown Characteristics of Natural Ester and Mineral Oil under DC Voltage

Energies ◽  
2020 ◽  
Vol 13 (7) ◽  
pp. 1818 ◽  
Author(s):  
Lin Cheng ◽  
Yi Jiang ◽  
Min Dan ◽  
Hao Wen ◽  
Yanqing Li ◽  
...  
Keyword(s):  
Electric Field ◽  
Particle Concentration ◽  
Breakdown Strength ◽  
Mineral Oil ◽  
Movement Speed ◽  
Testing Time ◽  
Copper Particles ◽  
Hvdc Transmission ◽  
Dc Electric Field ◽  
Natural Ester

The converter transformer is a key equipment in high voltage direct current (HVDC) transmission system. Its oil-paper insulation system in the valve winding and outlet bushing experiences AC, DC, AC/DC, and transient impulse voltages simultaneously. The oil contamination problem is more serious under DC electric field. Therefore, it is significant to investigate the characteristic of particles motion and accumulation under DC electric field. In this paper, first, the movement and accumulation behavior of fiber particles and copper particles in mineral oil and natural ester were recorded and simulated. Then, the influence of fiber and copper particles on the oil conductivity was analyzed. Finally, the DC breakdown strength of mineral oil and natural ester with different particles concentration was compared. Results show that the movement speed of copper particles was larger than that of fiber particles. Fiber impurities were easy to form bridges in mineral oil, while there was no impurity bridge in natural ester. The current density of mineral oil containing particles is larger than that of the natural ester at the same testing time. The DC 50% probability breakdown voltages of oil samples containing fiber and copper particles decreased linearly with the increase of particle concentration, and the decrease rate of DC 50% probability breakdown voltages of oil containing copper particles were faster than that of oil containing fiber particles. Compared to pure mineral oil, the DC breakdown voltages corresponding to 50% probability of contaminated mineral oil showed a decrease from 11.9% to 22.5% when the fiber particle concentration increased from 0.001% to 0.012%. The DC 50% probability breakdown voltages of contaminated mineral oil with copper particles decreased from 23.8% to 45.0% when the particle concentration increased from 0.1 g/L to 1.5g/L. However, the decline range of the figures for natural ester contaminated by fiber or copper particles showed a smaller drop.

THE FREQUENCY DEPENDENCE AND NON-LINEAR DIELECTRIC PROPERTY OF ER FLUID

1996 ◽  
Vol 10 (23n24) ◽  
pp. 3073-3080 ◽  
Author(s):  
KUNQUAN LU ◽  
WEIJIA WEN ◽  
CHENXI LI
Keyword(s):  
Dielectric Property ◽  
Field Strength ◽  
Electric Field ◽  
Frequency Dependence ◽  
Threshold Value ◽  
Shear Stresses ◽  
Linear Behavior ◽  
Non Linear ◽  
Er Fluids ◽  
Er Fluid

The frequency dependence of the shear stress in ac field and the non-linear dielectric property of ER fluid have been studied. We find that the shear stresses of some water-free ER fluids increase monotonously with the frequency and tend to reach saturated values at high frequency. The measurements on KNbO 3/silicone ER fluid show that the shear stresses under 103 Hz frequency a.c. field are several times or even an order larger than that under d.c. field for the same field strength. The studies of non-linear dielectric properties of ER fluids show that the permittivity of ER fluid increases linearly with increasing field strength when the electric field exceeds a threshold value E 1 and tends to a saturated constant beyond a high field strength E 2. Correspondingly the current density follows linear behavior no longer in the region between E 1 and E 2. A model based on the rearrangement of the particles under the electric field. which causes the variation of the dielectric property of the ER fluid, is proposed and the analysis is consistent with the measured results.

Study on the Influence of Electrode Collocation to Electric Field Characteristic of ESP

2014 ◽  
Vol 875-877 ◽  
pp. 1683-1686
Author(s):  
Cheng Liang Jia ◽  
You Shan Sun ◽  
Chao Huang ◽  
Wan Peng Zhang ◽  
Fang Chen
Keyword(s):  
Electric Field ◽  
Current Density ◽  
Surface Current ◽  
Electrode Configuration ◽  
Electrode Gap ◽  
Average Current Density ◽  
Surface Current Density ◽  
Discharge Electrode ◽  
Field Characteristic ◽  
Average Current

A laboratory-scale ESP with new electrode configuration was established to investigate the electric field characteristic. Eight teeth prick line and prick plate with the length of 20mm were employed as discharge electrodes, respectively. The effects of discharge electrode type and electrode gap on V-I characteristic and surface current density were studied. The results showed that the optimum electrode gaps were 350-400mm for eight teeth line and 300-350mm for prick plate, which could obtained higher average current density and lower variance.

Falling Film and Spray Evaporation Enhancement Using an Applied Electric Field

2000 ◽  
Vol 122 (4) ◽  
pp. 741-748 ◽  
Author(s):  
J. Darabi ◽  
M. M. Ohadi ◽  
S. V. Desiatoun
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Electric Field ◽  
Transfer Coefficient ◽  
Test Section ◽  
Applied Electric Field ◽  
Falling Film ◽  
Electrode Gap ◽  
Maximum Enhancement ◽  
The Heat Transfer Coefficient

The effect of an electric field on the falling-film evaporation of refrigerant R-134a on a vertical plate and three commercially available tubes was investigated experimentally. The plate test section was 25.4 mm wide and 76.2 mm long, and each tube test section was 19 mm in diameter and 140 mm long. Experiments were conducted in both falling film and spray evaporation modes. The effects of various parameters such as heat flux, refrigerant flow rate, electrode gap, and applied voltage were investigated. It was found that in the presence of an applied electric field, the maximum enhancement in the heat transfer coefficient for both falling film and spray evaporation modes on a plate was nearly the same. A maximum enhancement of fourfold in the heat transfer coefficient with the plate, 90 percent with the smooth tube, 110 percent with the Turbo BIII, and 30 percent with 19 fpi tube were obtained. The electrohydrodynamic power consumption in all cases was less than 0.12 percent of the total energy exchange rate in the test section. [S0022-1481(00)03003-6]

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