Heterogeneous plasma from a combined discharge in a vortex argon + steam mixture flow with aluminum particles in the tube of a plasma vortex reactor is experimentally studied. The discharge, plasma and working flow parameters are measured, and the coefficient of energy conversion in the plasma vortex reactor is measured. The electron temperature, the rotational and vibrational temperatures of excited molecular complexes, the temperature of metallic clusters, and the plasma electron concentration are estimated by spectral methods. A kinetic system for calculating the working regimes in the reactor using a discharge in steam with aluminum particles is proposed. A vortex pure steam flow with aluminum particles in the presence of a heating source is numerically modelled. The spatial-temporal distributions of the flow parameters, such as velocity, temperature, and pressure, are obtained together with the molar concentration distributions of the discharge mixture components.

В [1] предложены основы технологии получения водорода с использованием реакции гидратации микропорошков металлов в разряде в парах воды. В данной работе построена кинетическая схема газофазных реакций, протекающих в таком разряде с микрочастицами алюминия при атмосферном давлении. Полная кинетическая схема плазмохимических реакций в разряде паров воды в присутствии металлических микро- и наночастиц включает значительное число реакций [2]. Каналы, определяющие баланс заряженных и нейтральных частиц, весьма разнообразны, и учет их всех делает численное моделирование структуры закрученного течения в плазме вихревого реактора чрезвычайно трудной задачей. Поэтому обычно разрабатывают ряд упрощенных кинетических схем, позволяющих рассчитать основные параметры.

Two promising designs of counterflow vortex reactor were numerically investigated. Such apparatus utilizes reverse flow to withdraw thermal energy and products from interelectrode area. Complex gasdynamic structure of the water-vapor flow was investigated using turbulent three-dimensional simulation employing Reynolds averaged Navier-Stokes equations along with SST k turbulence model technique tested in earlier papers. Presented velocity profiles and heat flux reports demonstrate viability of both approaches.

A study of the discharge plasma with a vortex flow of an argon + water vapor mixture with aluminum particles in a tube of a plasma vortex reactor (PVR) was carried out. The parameters of the discharge, plasma, and working flow in the PVR have been measured. Spectral methods were used to estimate the electron temperature, rotational and vibrational temperatures of excited molecular complexes, the temperature of metal clusters, and the electron density of plasma. A kinetic scheme is proposed for calculating the operating modes in a reactor using a water vapor discharge with aluminum particles. Numerical simulation of a vortex flow of pure water vapor with aluminum particles in the presence of a heating source is carried out.

Magnetoacoustic(MA) waves in the plasma with acoustic activity caused by the non-adiabatic processes is under investigation. Acoustic activity of the medium is a consequence of temperature and density dependence of heating and cooling process which take place in the medium. It is shown that non-adiabatic process results in the frequency dependence of group/phase velocity. Effect of frequency dependence is most pronounced near the frequency defined by the inverted heating/cooling time. In the low-/high-frequency limits effect of frequency dependence can be neglected. However, in contrast to high-frequency case where phase/group velocities equal to their value in the equilibrium medium, in the low-frequency limit both velocities are defined by the non-adiabatic processes only. Furthermore, frequency dependence of group velocity in contrast to phase velocity has as an extrema which can be maxima or minima depending on type of dispersion (negative or positive, respectively). This result indicates that some harmonics in non-adiabatic plasma can propagate faster or slower than all others. The expression for group velocity has been obtained under the assumption of weak dispersion/dissipation. Effects caused by the weak but finite dispersion/dissipation on group velocity is analyzed as well.

This work is a continuation of our previous studies [1-10] of physical parameters and properties of a long-lived heterogeneous plasmoid (plasma formation with erosive nanoclusters) created by combined discharge in a high-speed swirl flow. Here interaction of metal nanoclusters with hydrogen atoms is studied in a plasma vortex reactor (PVR) with argon-water steam mixture. Metal nanoclusters were created by nickel cathode’s erosion at combined discharge on. Dissociated hydrogen atoms and ions were obtained in water steam by electric discharge. These hydrogen atoms and ions interacted with metal nanoclusters, which resulted in the creation of a stable plasmoid in a swirl gas flow. This plasmoid has been found to create intensive soft X-ray radiation. Plasma parameters of this plasmoid were measured by optical spectroscopy method. It has been obtained that there is a high non-equilibrium plasmoid: Te > TV >> TR. The measured coefficient of energy performance of this plasmoid is about COP = 2÷10. This extra power release in plasmoid is supposed to be connected with internal excited electrons. The obtained experimental results have proved our suggestion.

Numerical simulations of the non-stationary three-dimensional swirling Ar flow are presented for plasma vortex reactor (PVR) with a paraxial heat source at various positions of the heat source and electrode forms. Flow and duct parameters correspond to the experimental conditions. Flow velocity and thermal fields have been obtained.

A numerical study is made of the structure of a swirling argon flow with atmospheric pressure in a closed tube duct with an asymmetric gas outlet, a localized heat source simulating gas heating by a longitudinal pulse repetitive HF discharge, and the source of an acoustic field simulating sound generation by discharge pulses. It is shown that, at supercritical amplitudes of the acoustic field, helical gas-dynamic and thermal flows capable of inducing the formation of a discharge channel with a structure that is close to the shape of a helical flow can form. The results are shown to qualitatively agree with the known experimental data.

Numerical simulation of the turbulent three-dimensional swirling flow in experimentally tested plasma vortex reactor were carried out to ascertain that earlier limited modelling properly represents flow phenomena and to provide further insights into use of such apparatus. Exact experimental geometry, electrode location that maximizes energy utilization in accordance with previous research, model heat source, and reduced mixture composition (pure Ar) were used. A qualitative agreement between the results of the calculations and the experimental data for pure argon has been obtained. Structure of counterflow zone, crucial for energy extraction, and corresponding temperature field are presented.

The effect of twisting a near-wall gas flow around a cylindrical model induced by a magnetoplasma actuator on the external subsonic flow around this model has been studied.

The absolute instability of a Rankine vortex with an axial flow and paraxial heat source is investigated. The dispersion relation for vortex modes is derived analytically. The dependence of dispersion properties of the media on control parameters such as swirl parameter S, velocity a, and heat source power (density parameter Q) is studied. The frequency of helical waves increases and the increment decreases with increasing heat source power, accompanied by a decrease in the width of the neutral stability region. Numerical analysis also suggests that one of the dispersion curve branches could include an instability region of a parametric nature.

Numerical simulation of the non-stationary three-dimensional swirling flow is presented for an open tube with a paraxial heat source. In the considered type of swirling flows, it is shown that a precessing vortex core (PVC) appears. The obtained PVC is a left-handed co-rotated bending single-vortex structure. The influence of the heat release enhancement on parameters of PVC is investigated. Using various turbulence models (the Spalart-Allmaras, k-omega and SST models), it is shown that an increase in the heat-source power leads to an increase in the PVC frequency and to a decrease in the amplitude of PVC oscillations. Moreover, we conduct the linear stability analysis of the simplified flow model with paraxial heating (the Rankine vortex with the piecewise axial flow and density) and demonstrate that its results correspond to the results of numerical simulations rather well. In particular, we prove that the left-handed bending mode (m = +1) is the most unstable one in the low-density wake and its frequency increases with a decrease of density ratio that is similar to the behavior of precession frequency with an increase of heat source power. (C) 2016 Elsevier Inc. All rights reserved.

The nonlinear evolution of fast and slow magnetoacoustic waves in the plasma medium with non-adiabatic heating/cooling processes is under consideration. The magnetic field is assumed to be inclined at an arbitrary angle to the direction of wave propagation. The non-adiabatic processes depend on temperature and density and result in the steady non-equilibrium state of the medium. The steady state caused by the balance between heating and cooling rates makes it possible for thermal instabilities to appear. This research is focused on the wave mode of thermal instability (isentropic instability). The presence of other modes of the thermal instability is neglected. The isentropic instability influences on acoustic and magnetoacoustic waves and causes wave amplification. Linear analysis predicts simultaneous amplification of fast and slow magnetoacoustic waves with different increments. Furthermore, analysis predicts simultaneous disintegration of fast and slow waves on the sequences of autowave (self-sustaining) shock pulses. Numerical simulation of full system of one-dimensional magneto-hydrodynamic equations supports these results. The parameters of described autowave pulses are in good agreement with values predicted by our analytical model.

The structure of plasma discharge in swirling flow is determined by electromagnetic field as well as gas-dynamic fields. In particular, the experiment performed by Klimov et al. showed significant changes in plasma high-frequency discharge structure in the tube at pulse modulation frequency close to the eigenfrequency of acoustic resonator. In this case, the excitation of standing acoustic wave in the tube led to the formation of large single loop on the longitudinal plasma filament. In current work a mechanism providing generation of solitary spiral waves in swirling flows is presented. It was found, that the resonant three-wave interaction between the main acoustic mode of resonator and two bending modes with azimuthal wavenumbers m = + 1 and m = -1 can lead to a parametric amplification of bending modes and formation of secondary spiral gas and heat flow. Due to increased ionization rate and drop in channel resistance, the discharge filament follows the heated spiral gas flow. By means of perturbation analysis, it was shown, that the deformed vortex line takes the shape of a helix, bounded by an envelope, which matches Hasimoto soliton. This shape varies with the acoustic Mach number. If the envelope is sufficiently narrow, then at supercritical Mach number the helix turns into a filament with a single closed loop. The vortex core shape and its evolution are in qualitative coincidence with the experimentally observed behaviour of plasma filament.

Streamlining of a circular cylinder with a localized heat source modeling an MHD actuator in which the plasma arc channel moves along the cylinder surface under the action of the Lorentz force in a radial magnetic field is studied experimentally and simulated numerically. It is shown that the presence of a moving heat release region leads to a break in the symmetry in cylinder streamlining by the external flow and the appearance of a nonzero lift force and circulation.

The equations describing the structure of the average acoustic field of well streamlined thin body in supersonic gas flow of the non-equilibrium random media are received. It is founded the dependence between shock wave front shape and relation of correlation radius and wave length. The results are compared with experimental data.

The wave-wave interaction of linearly polarized Alfven waves and a powerful acoustic wave in the acoustically active plasma medium have been analyzed. The acoustical activity is a result of the isentropic instability due to the radiative cooling processes and various exothermal heating processes in the medium. The both processes depends on temperature and density. We investigate the possibility of the energy transfer from unstable acoustic waves into stable Alfven waves. For this reason, we provide the analysis of the three-wave interaction of waves propagating in opposite (or same) directions. Moreover, the two-wave interaction of the waves propagating in the same direction is discussed as well. By the use of the perturbation theory we obtain the reduced systems of magneto-hydrodynamics equations describing wave-wave interaction process without the frequency detuning. The analytical solutions of these systems of equations and wave increments are obtained as well. It is shown that Alfven wave amplification could occur in the high-beta plasma.