Calculation of the flow of a gas with particles past bluff bodies with allowance for the effect of reflected particles on the flow of the aerosol

Translated from Zhurnal Prikladnoi Mekhaniki i Tekhnicheskoi Fiziki, No. 6, pp. 67–74, November–December 1990.     

Time-dependent charging of an electrically insulated sphere in a turbulent stream with the ion component in the presence of an electric field

The time-dependent process of charge accumulation on an electrically insulated sphere located in a turbulent stream with the ion component in the presence of an electric field is considered. The process is simulated numerically on the basis of the time-dependent electrodynamic equations and averaged Navier-Stokes equations (RANS approximation) using the Sekundov single-parameter turbulent viscosity model. The distributions of the ion number density, electric current, and potential are determined. Features of the obtained time dependence of the sphere potential are analyzed.     

Equations of electrohydrodynamics of weakly ionized aerosols with diffusion charging of dispersed phase particles

A closed model describing the motion of weakly ionized aerosols with allowance for dispersed phase particle charging processes due to ion deposition is constructed within the framework of continuum mechanics [1]. Both the general process of particle charging in a weakly ionized gas and its limiting cases, where the limiting stage of the process is the diffusion of the ions towards the particles or the reactions leading to their deposition on the particles, are investigated. Expressions are obtained for the positive and negative ion flows to a particle in a weakly ionized gas. The basic equations of electrohydro-dynamics of weakly ionized aerosols, in which the dispersed phase particle charging mechanism in question leads to the interphase transfer of elctrical charge, are formulated. Cases where the system of equations of electrohydrodynamics obtained can be simplified by replacing the differential equations of motion and charging of the dispersed phase and, moreover, the positive and negative ion balance equations by algebraic relations such as Ohm's law and Saha's equation are investigated.Translated from Izvestiya Akademii Nauk SSSR, Mekhanika Zhidkosti i Gaza, No. 1, pp. 54–60, January–February, 1986.     

Self-similar problems of convective diffusion in the presence of heterogeneous chemical reactions with allowance for thermal diffusion effects

A number of studies have been made of the problem of the effect of a temperature gradient on mass transfer in a forced viscous fluid flow. The question of allowing for thermal diffusion effects has been examined in connection with flow around bodies [1–4], duct flow [5], and jet flows [6,7]. Recently, in addition to the problem of thermal diffusion separation, the attention of investigators has been claimed by the problem of taking into account the effect of thermal diffusion on mass transfer in a convective flow in the presence of chemical reactions on the flow surfaces [4].     

Simple waves in a “gas” of noncolliding polarizable particles in an electric field

The article describes a study of a new phenomena which occur during the motion of dispersed polarizable media which have different permittivities in the dispersing (carrier) and dispersed phases in electromagnetic fields.Translated from Izvestiya Akademii Nauk SSSR, Mekhanika Zhidkosti i Gaza, No. 4, pp. 121–127, July–August, 1984.     

Model of a gas of solid particles with allowance for inelastic collisions

A study is made of the structure of the interaction region of a flow of solid particles with a surface (or another flow) in the case when the width of this region is much greater than the mean free path of the particles between collisions. The disperse phase is described by means of a model of an ideal non-heat-conducting gas of imperfectly elastic spherical particles. For simplicity, the influence of the carrier medium on the motion of the particles is ignored.     

Effect of an electric field on the nitrogen oxide emission and structure of a laminar propane diffusion flame

The effect of an electric field E on the structure and nitrogen oxide NO_x emission of an individual laminar propane diffusion flame is experimentally investigated. The current-voltage characteristics of the flame, its deformation, the fuel-air ratio and the NO_x emission are determined for positive and negative burner polarities. A reduction in NO_x emission (up to 30% with respect to the emission index) is demonstrated in the case of negative burner polarity. A cause-and-effect relationship between the processes in the flame is proposed: the presence in the flame of positively charged ions and soot particles; the motion of the ions in the E field and the onset of an induced electrohydrodynamic flow directed towards the negatively charged burner; the retention and increase in the concentration of soot particles in the lower region of the flame, which leads to an increase in soot particle radiation and hence to a decrease in the temperature of the flame front and a corresponding reduction in NO_x emission. The electrohydrodynamic aspects of the problem are subjected to a qualitative analysis.Moscow. Translated from Izvestiya Rossiiskoi Akademii Nauk, Mekhanika Zhidkosti i Gaza, No. 2, pp. 13–23, March–April, 1995.     

A mathematical model for an alloy solidification problem in the presence of an electric field

A one-dimensional mathematical model for a process of solidification of a binary alloy in the presence of an electric field is studied. A situation in which the thermal properties of each phase are different and the latent heat is non-zero is considered. A quasi-static approximation for the thermal and electric fields is used. Local existence and uniqueness of a classical solution to the resulting free boundary problem are proved for two kinds of boundary conditions. Moreover, under particular hypotheses, the monotonicity of the free boundary and the global existence of the solution is proved.

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Sommario Si studia un modello matematico unidimensionale per un processo di solidificazione di una lega binaria in presenza di un campo elettrico. Si considera una situazione in cui le proprietà termiche di ogni fase sono differenti e il calore latente è non nullo. Si usa una approssimazione quasi-statica per i campi elettrico e termico. Si dimostra l'esistenza locale e l'unicità di una soluzione classica per il problema di frontiera libera risultante con due tipi di condizioni di bordo. Inoltre si dimostra, sotto particolari ipotesi, la monotonia della frontiera libera e l'esistenza di soluzione globale.

     

Polarization of a plasma in an electric field

A study has been made of the electrostatic polarization of a plasma in an applied electric field, i. e., the process of charge separation in the case when a steady current flow through the plasma is excluded.The authors are deeply grateful to G. A. Lyubimov and S. A. Regirer for useful discussion.     

Charged jet of an incompressible liquid in an electric field

The problem of the jet flow of an incompressible liquid with free boundaries in an electric field is solved in the approximation of a laminar boundary layer. An exact solution for a round jet is found in the class of self-similar solutions. In the case of a flat slit jet, a solution is constructed in the form of a series in powers of the coordinate transverse to the plane of symmetry. The dependence of the radius (half-width) on the longitudinal coordinate is given. Branch of the Karpov Physicochemistry Institute, State Science Center, Obninsk 249020. Karpov Physicochemistry Institute, State Science Center, Moscow 115523. Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 39, No. 4, pp. 12–16, July–August, 1998.     

Rheological behaviour of brownian interacting particles in uniaxial flow combined with electric (magnetic) field

Elastic and viscous stress contributions, elongational viscosity, and stress-orientation characteristics have been analysed using an ‘equilibrium’ orientation distribution of rigid ellipsoids in steady elongational flow. Effects of electric or magnetic field and orientation-dependent dipole and quadrupole interparticle interactions have been discussed.     

The pseudoturbulent diffusion of particles in homogeneous suspensions

The effective diffusion coefficients for suspended particles caused by their pseudoturbulent pulsations, are treated. Derivatives of the dynamic variables which determine the average motion of the locally homogeneous suspension are neglected.Translated from Zhurnal Prikladnoi Mekhaniki i Tekhnicheskoi Fiziki, Vol. 11, No. 1, January–February, pp 67–72, 1970.     

Excitation of a spherical piezoemitter which generates nonsteady electric signals with allowance for processes in the cable channel

The problem of the excitation of a thin-walled spherical piezoemitter which generates nonsteady electric signals is examined with allowance for processes in a long cable used with the piezoemitter. An analytic method of solving the problem is developed on the basis of the Laplace time transform. Boundary conditions are satisfied in the space of the originals, allowing the problem to be reduced to a system of Volterra integral equations. Numerical results are presented. S. P. Timoshenko Institute of Mechanics, National Academy of Sciences of Ukraine, Kiev, Ukraine. Translated from Prikladnaya Mekhanika, Vol. 35, No. 2, pp. 41–46, February, 1999     

Solution of the three-dimensional turbomachinery blade row flow field problem with allowance for viscosity effects

The three-dimensional viscous compressible flow in the interblade channel of a turbomachine blade row is examined. A mathematical model of steadystate separated turbulent polytropic-gas flow with allowance for wall flow effects is proposed. It is assumed that the thickness of the boundary layers and the scales of the wall flow interaction zones are small as compared with the characteristic dimension of the system. Subsonic flow calculations are made for near-design flow regimes.Translated from Izvestiya Akademii Nauk SSSR, Mekhanika Zhidkosti i Gaza, No. 6, pp. 119–127, November–December, 1991.The authors are grateful to G. Yu. Stepanov for his interest in their work and valuable advice.     

Explosion in an inhomogeneous atmosphere with allowance for condensation of evaporated matter

A study is made of the process of condensation in an expanding cloud consisting of iron vapor in an inhomogeneous atmosphere. Numerical solutions of problems are used to investigate explosive processes for characteristic heights and initial cloud parameters using a model of quasisteady nucleation. The gas-dynamic characteristics of the medium are obtained at different times together with the size distribution function of the liquid droplets that form.Translated from Izvestiya Rossiiskoi Akademii Nauk, Mekhanika Zhidkosti i Gaza, No. 3, pp. 154–162, May–June, 1993.