Electrical oscillations in combustion of magnesium particles in a constant electric field

For a magnesium particle (6 mm in diameter)burning in air, electrical oscillations in the measuring circuit were found at a threshold intensity of the external constant electric field of 30 kV/m. Spectral analysis of the oscillations revealed low-frequency (5 kHz) and high-frequency (25 kHz) oscillation modes. It is shown that low-frequency electrical oscillations are due to variations in the density of the positive space charge of submicron MgO particles between the metal particle surface and the negatively charged plate of the capacitor. High-frequency oscillations are caused by modulation of the dielectric permittivity of the medium in the chemical condensation zone of the magnesium particle. The cause of the modulation is instability in the condensation zone of the burning particle, which is manifested in the excitation of longitudinal oscillations of the MgO particles (dust acoustic waves) propagating in the thermionic plasma of magnesium combustion products. The occurrence of the dust acoustic waves is due to streaming instability caused by differences in the drift velocities of charge carriers in the electric field.     

Effect of an external electric field on the combustion parameters and electrification of an electrical plant nozzle

Karaganda. Translated from Fizika Goreniya i Vzryva, Vol. 26, No. 6, pp. 74–78, November–December, 1990.     

Effect of stochasticity of the spatial distribution of particles in a gas suspension on combustion front propagation

A statistical model of combustion of a gas suspension of solid particles is proposed. The model takes into account the influence of the stochastic spatial distribution of particles on the combustion front velocity. The Bose-Einstein distribution in the presentation of occupation numbers is used as the basic mathematical apparatus of the model. The model offers an explanation for the effect observed in some experiments, which is associated with the shift of the combustion front velocity peak to the range of fuel-rich gas suspensions. The limits of applicability of the proposed statistical model to real gas suspensions are estimated.     

Effect of an external electrical field on ignition and combustion processes

Published results of experimental studies on the effect of an external sub-breakdown electrical field on and combustion characteristics are reviewed. Analysis of the material presented reveals general princip features of the electrophysical aspects of combustion of various fuel compositions as a function of co practical application conditions.N. É. Bauman Moscow State Technical Institute. 107005 Moscow. Translated from Fizika Goreniya i Vzryva, Vol. 30, No. 3, pp. 3–12, May–June, 1994.     

Mathematical modeling of combustion of a frozen suspension of nanosized aluminum

A mathematical model of combustion of a composite solid propellant called ALICE (frozen suspension of nanosized aluminum in water) is presented. The model takes into account the combustion of aluminum nanoparticles in water vapor, the motion of combustion products, and the smaller velocity of particles as compared to the gas. The calculated burning rate is consistent with available experimental data on the burning rate of ALICE as a function of pressure.     

Effect of laser radiation and electric field on combustion of hydrocarbon-air mixtures

Publications on combustion of hydrocarbon-air mixtures under the action of a weak electric field and laser radiation are analyzed. A specific feature of the authors’ experimental study is a pulsed-periodic action of an electric field and focused laser radiation, which does not lead to electric discharge or optical breakdown. Numerous experiments reveal a noticeable effect of weak electric fields on combustion processes. Application of an electric field may result in expansion of the limits of flammability and combustion of fuel-air mixtures, changes (decrease or increase) in the burning rate, shifting of flame stabilization toward lean mixtures, reduction of the concentration of hazardous substances (for instance, NO _x and CO) in combustion products, etc. __________ Translated from Fizika Goreniya i Vzryva, Vol. 45, No. 4, pp. 77–85, July–August, 2009.     

Effect of acceleration on agglomeration of aluminum particles during combustion of composite solid propellants

The effect of the normal acceleration (g-load) on formation of agglomerates and their distribution function is examined within the framework of the statistical model of aluminum agglomeration. A parametric study of aluminum agglomeration with different values of normal g-loads is performed. The theory developed predicts a new effect, namely, a nonmonotonic dependence of the mean-mass size of agglomerates leaving the burning surface on the magnitude of normal g-loads: with increasing g-load, the mean-mass size of agglomerates can increase if the g-loads are low or moderate and decrease if the g-loads are high; in the latter case, the size distribution of agglomerates becomes less spread and more stable. __________ Translated from Fizika Goreniya i Vzryva, Vol. 43, No. 6, pp. 40–50, November–December, 2007.     

Effects of an external electric field on the collection efficiency of air filters: Filtration mechanisms with an external e-field

An external electric field was applied on the filter to improve its collection efficiency, and the collection efficiencies of the different filters under various conditions were evaluated. Dominant electrical filtration mechanisms for each condition were investigated using experimental and theoretical approaches. Four types of air filters were used as test filters: a charged fiber filter, a low-grade filter with 50% collection efficiency in the most penetration particle size (MPPS) zone, and two high-grade filters with more than 95% collection efficiency in the MPPS zone. Three different particle charge states—neutralized, single-charged and uncharged—were considered. For neutralized particles, the external electric field led to a 14.5%p. and 2.5%p. increase in the collection efficiencies of the low-grade filter and charged fiber filter, respectively. With the electric field, the collection efficiency of the low-grade filter increased by 30%p. for single-charged particles. The electric field also affected the collection efficiencies of the charged filter and high-grade filters, but the effect was not significant. For uncharged particles, the electric field did not lead to a remarkable increase in the collection efficiencies of any of the filters. Through experimental and theoretical analysis, it was found that the polarization force imposed on the charged fiber was the dominant factor for the charged fiber filter regardless of application of the external electric field. The Coulombic force imposed on the electric field was the dominant factor for the low-grade filter, while both the Coulombic and the polarization forces affected the collection efficiency of the high-grade filter.

Copyright © 2017 American Association for Aerosol Research     

Effect of an external electric field on the charge distribution of electrostatic coagulation

This article analyzes the effect of an external electric field on the charge distribution of bipolar and unipolar charged particles numerically by solving the coagulation equation for charged particles, based on the analytical expression for the coagulation coefficient [Wang, L. Z., Zhang, X. R., & Zhu, K. Q. (2005). An analytical expression for the coagulation coefficient of bipolarly charged particles by an external electric field with the effect of Coulomb force. Journal of Aerosol Science, 36, 1050–1055]. For symmetric bipolar charged particles, the external electric field does not change the symmetry of the initial charge distribution as the coagulation time increases. In addition, the particle number concentration decays monotonically during coagulation regardless of the magnitude of the particle charge. For asymmetric bipolar charged and unipolar charged particles, however, the particle number concentration does not decay monotonically for each value of charge during coagulation, due to the effect of an external electric field.     

Effect of an electric field on the radial distribution of the combustion products of graphite

Combustion, Explosion, and Shock Waves -     

Two-stage combustion of an ultradispersed aluminum powder in air

Tomsk. Translated from Fizika Goreniya i Vzryva, Vol. 26, No. 2, pp. 71–72, March–April, 1990.