Simulation of the integral electric current characteristics of unsteady-state current passage through liquid dielectrics

Abstract

The paper presents the technique for computing current-time characteristics of the transient regime, taking place after the pulsed application or change of high voltage, and current-voltage ones obtained with the voltage sawtooth modulation. The basis of the simulation is the complete set of electrohydrodynamic equations with both the convective and the migration mechanisms of charge transport being taken into account jointly. The numerical calculations were performed using commercial software package COMSOL Multiphysics based on the finite element method. The simulation was carried out for the needle-plane electrode system. The unsteady-state current passage processes, including electrohydrodynamic flow formation, were calculated. The interrelation between the latter and the total current passing through the electrical circuit were investigated. The shape and features of the current-voltage characteristics obtained with the voltage sawtooth modulation were shown to be dependent on the mechanism of charge formation. The qualitative comparison between the simulated and the original experimental data has shown a good agreement.

Structural characteristics of electrohydrodynamic jets induced by a blade‐plane actuator subjected to highly non‐uniform electric fields: Parametric investigation through the particle image velocimetry techniques

“…Generally, the electric field and the flow velocity vary at different locations between the electrodes. To assess the overall effect, we choose the equivalent mean electric $${\overline{E}}_{\mathrm{e}\mathrm{q}}$$ and centreline mean velocity $${\overline{V}}_{y,\mathrm{c}}$$ (not plotted in this paper) to calculate the mean drift velocity $${\overline{V}}_{\mathrm{d}}$$ = $$\kappa {\overline{E}}_{\mathrm{e}\mathrm{q}}$$ and the mean convective velocity $${\overline{V}}_{\mathrm{c}}$$ = $${\overline{V}}_{y,\mathrm{c}}$$, where $$\kappa $$ = 1 × 10 −8 m 2 /(V s) is the ion mobility [1, 16]. The plot of $${\overline{V}}_{\mathrm{c}}/{\overline{V}}_{\mathrm{d}}$$ as a function of $${\overline{E}}_{\mathrm{e}\mathrm{q}}$$ is shown in Figure 6.…”

“…Under the action of an external electric field, the dissociation effect of impurities in dielectric liquids with conductivity ranging from 10 −11 to 10 −7 S/m is enhanced [2], breaking the dynamic equilibrium between dissociation and recombination that was previously achieved in the absence of an electric field [45]. This can be demonstrated by the electric field-dependent conductivity equation associated with the Wien effect [16,40].…”

“…Generally, the electric field and the flow velocity vary at different locations between the electrodes. To assess the overall effect, we choose the equivalent mean electric E eq and centreline mean velocity V y;c (not plotted in this paper) to calculate the mean drift velocity V d = κE eq and the mean convective velocity V c = V y;c , where κ = 1 � 10 −8 m 2 /(V s) is the ion mobility [1,16]. The plot of V c =V d as a function of E eq is shown in Figure 6.…”

“…To better understand these EHD flows, significant progress has been made in theories related to the nature and origin of space charge [9,10], in experiments related to flow and current measurements [11,12], and in simulations associated with modelling [13], electroconvective instability [14] and verification of experiments [15][16][17]. The configuration of the actuator of the pump, the propriety of the dielectric liquid, and the applied signal can all play a significant role in determining injection strength, dissociation intensity, and flow structure.…”

Estimating the effect of asymmetric electrodes in bipolar discharge ion wind generator

“…Numerical studies of ion wind generator have been presented for most ion wind configurations [43][44][45][46][47][48]. In this work, a simplified charge transport model for the discharge drift area is used with the boundary condition of charge density at the tips of electrodes given by the measured current-voltage (I-V) characteristics of the corona to simulate the motion of ion wind.…”