V. A. Bityurin

Spectral and kinetic analysis of heterogeneous gas discharge plasma in the flow of an Al, H2O, and Ar mixture

Plasma excited by a longitudinal pulse-periodic discharge in a mixed flow of a buffer gas (Ar), oxidizer (H2O), and aluminum dust is studied. The salient features of its kinetics are the atomic and molecular electronic channels of Al atom transformation, which were not taken into account earlier. They accelerate not only the oxidation process but also aluminum vaporization because the excitation and ionization energies are finally released on the surface of aluminum particles. This work is devoted to experimental and theoretical analysis of these channels.

Ground MHD experiments in hypersonic flows

The paper presents an analysis of experimental and numerical studies devoted to MHD interaction in hypersonic gas flows. The most pronounced and representative experiments performed during several decades are considered from the following points of view: (a) whether detected facts result from MHD effects; (b) whether the absence of such facts (features of MHD interaction) testifies to the absence of MHD interaction; (c) what ground-based experiment aids in preparing a flight experiment; (d) what is the role of numerical experiment in magnetic aerodynamics. The problems of unambiguous interpretation of experimental results are discussed. Effects manifested as MHD phenomena are considered. Problems of the sufficiency of modern numerical models for adequate description of MHD interaction in ground and flight conditions are also discussed.

Kinetic model of Al oxidation by water vapor in heterogeneous plasma: Heterophase kinetics

The kinetic model of gas and heterophase plasma-chemical processes taking place in the working zone of a reactor is extended to the evaporation of aluminum from the surface of microparticles, which results in the mean value of the flux density and evaporation time. It is shown that the balance of aluminum atoms in the working zone is determined by the heterogeneous processes of evaporation of low-melting aluminum and adhesion of refractory oxides, which is the dominant aluminum-containing component of the plasma. The time of flight of microparticles through the working zone in a gas-discharge aluminum-water reactor with a pumping system is experimentally found, which, under the conditions created, coincides with the burnout time of aluminum microparticles. The mechanisms of burnout and reproduction of microparticles (evaporation and microexplosions) are determined, reducing the average size of microparticles in the working zone from 100 to 10 μm.

Aerodynamic quality management for the NACA 23012 airfoil model using the surface high-frequency discharge

The effect of the surface capacity HF discharge on airfoil flow-around has been studied in the situation when the oncoming flow velocity is 20 m/s and the Reynolds numbers are Re = 105. The power delivered to discharge was modulated with a frequency of 3 × 102–2 × 104 Hz, which corresponds to a Strouhal number of St = 1.2–80, and the average electric power (Wav) was 50–400 W. It has been indicated that the aerodynamic drag decreased and the lift increased at stall and post-stall angles of attack when the HF dielectric barrier discharge was turned on. A nonstationary stochastic change in the Cx and Cy aerodynamic characteristics was observed at a stall angle in the St = 4–10 range of Strouhal numbers when the power was insufficient (Wav ≈ 100 W).

Electrodynamic model of a microwave streamer

A microwave streamer model based on analytical electrodynamic relationships is proposed that allows the evolution of a streamer to be described both during its propagation along the external electric field and upon stopping. The results are compared to those of two-dimensional numerical simulations of the electrostatic stage of streamer evolution in air.

Determining integral characteristics of a microwave streamer by using a scattered signal

The dynamics of the power-flux density scattered by a microwave streamer in air was studied experimentally near the breakdown threshold in the range of pressures from 104 to 1.4 × 104 Pa. Based on the measurement data, we estimated amplitudes of the total charge and current, as well as the effective scattering surface of the plasma dipole formed.

A high-frequency discharge on a dielectric surface

Plasma generation from a high-frequency (HF) oscillator, operating in the frequency range from hundreds of kilohertz to hundreds of megahertz, is one of the most interesting and promising ways of plasma creation in gas flows. A feature of an HF oscillator is that it utilizes only a single electrode, which can be placed inside the body and have no direct contact with the medium. The surrounding medium including the elements of the setup acts as the second electrode.

Reducing radiative losses in aluminum-hydrogen MHD generators

Rigorous estimations are obtained for the integral thermal radiation flux from a working substance to walls of a high-temperature setup. These estimations are convenient for engineering calculations and can be used in solving problems related to radiative losses in promising aluminum-hydrogen MHD generators.

Specific features of electric discharge-gas flow interaction in an external magnetic field

Ensuring stable and effective mixing and burning of gaseous fuel and oxidant in a supersonic flow within a chamber of appropriate dimensions is an important task in the creation of high-rate flow combustion systems. A promising means of intensive mixing of cocurrent jets is offered by the magnetohydrodynamic (MHD) method [1], which is based on the initiation of pulsed electric discharge in the gas flow and the interaction of this discharge with an external magnetic field for the development of vorticity. Specific features of threedimensional (3D) evolution of the discharge under such conditions have been studied using quasi-3D modeling, which is, in addition to 2D modeling and physical experiments, an affective tool for investigation of the electric discharge-gas flow interaction in the applied magnetic field.

Dynamics of dipole-type discharge formation studied by the method of microwave scattering

Microwave scattering (MWS) measurements have been used to study the evolution of a plasma structure comprising a linear chain of thin dipoles (with thicknesses small compared to wavelength) formed in air at pressures within (1–1.4) × 104 Pa (slightly above the breakdown threshold). An analysis of the MWS dynamics reveals the main stages in development of both a single plasma dipole and the entire structure. The average speed of elongation of a plasma structure (microwave streamer) in the direction of applied electric field E0 and the average velocity of propagation of the discharge front toward the microwave source are determined.