Anatoly Klimov

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.

Effect of heterogeneous discharge plasma on shock wave structure and propagation

New experimental results on shock wave (SW) propagatiofi’and SW structure in cold non-equilibrium weakly ionized plasma are presented, and are correlated with those previously published. The present work is also devoted to development of a theoretical model of phenomena. We purpose that there are hot filaments, inside of the plasma volume, which have extremely high plasma parameters. Simulation of the SW propagation in this structural plasma was conducted and is presented in this work. It was revealed that-the SW structure in this structural medium is very close to the experimental results. Under this condition the temperature of hot filaments rather than the average plasma temperature controls SW velocity. Description of plasma volume as nonhomogeneous formation is a general idea that explains peculiarities of SW propagation through it. Introduction. Experimental studies and simulations have proved the possibility of decreasing SW and acoustic wave (AW) intensity by a factor of up to 10 and an increase of sound speed up to about 2000 ms in non-equilibrium plasma. Significantly, the thermal effects in a plasma do not explain the dispersion and dissipation of AW and SW in a plasma area. So, the study of AW (SW) dispersion and dissipation in Low Temperature Nonequilibrium Plasma (LNp) is very important for development of plasma aerodynamics. An idea of significant non-uniformity in distribution of plasma parameters has allowed approaching to explanation of the most effects. Recently, several theoretic groups have tried to explain the effects by means of spatial non-homogeneity of plasma parameters [l-5]. Experimental studies and simulations have also revealed very significant dispersion and dissipation of SW are obtained in non-equilibrium cold (in average) pulse discharge. The important role of non-uniformities in the plasma formation in pulse discharges is one of the preliminary results of this work. A new approach to the plasma formation process, namely, the large influence of nonuniformity of discharge parameters distribution on SW propagation, forces us to repeat measurements of ,SW .velocity in plasma and visualization at specific condition of non-steady heterogeneous discharge. ,,

Analysis of Non-Thermal Plasma Aerodynamics Effects

The series of recent plasma aerodynamics observations are discussed from the point of view of «non-thermal» effects involved. The common physical approach is proposed to treat and understand such phenomena. This approach is based on more detailed evaluation of the ion current effects, which are more pronounced in regions of space charged formed by convection, diffusion and/or «unbalanced» charged particles drift in external electric field

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).

Flow Control over NACA 23012 Airfoil Model by Surface HF Plasma Actuator

It has been revealed that pulse periodic surface high frequency discharge operation can lead to stall delay for NACA23012 airfoil at Re <400k and M<0.3 1 . This work is devoted to the study of this plasma effect on the leading edge stall by means of PIV. Separation dynamics is studied in two regimes: single pulse excitation and burst excitation. One can conclude that separation region evolution consist of a series of local reattachment processes due to separate discharge pulses. Totally, separation point was shifted downstream by 25% chord length. The study was performed at airflow velocity 20m/s and Reynolds number Re~80k. The typical parameters of CHFD used in these experiments are the followings: HF frequency FHF~350 kHz, modulation frequency FM=10-10 4 Hz, mean HF power NHF< 100W.

Flow Around Wing Model with a Surface HF Discharge

Airflow around wing model W, controlled by pulse-repetitive HF discharge, is studied at flow velocities up to 100m/s, Pst~ 1 Bar and Re < 10 5 in this work. Transversal capacity coupled HF discharge (CHFD) with the typical frequency of f= 350 kHz is created on the model’s surface near its leading edge. It is revealed that there is drag decrease of the model W at high HF pulse power input in plasma and large attack angles (AoA). These results are sensitive to Strouchal’s number value. There are two drag minimums at the Sh~1 and the Sh~5. Mean power input in plasma doesn’t exceed 10 W/cm at the pulse HF power about of ~1 kW. Shadow pictures of the airflow around the wing model show a large-scale vortex creation near the separation line. There are acoustic waves (Fa~ 600 kHz) created by surface CHFD.

Surface HF Plasma Actuator in Airflow

The paper presents the first results on the experimental and numerical studied of the novel configuration of the HF discharge at the conical body in airflow. The effect of the three-electrode configuration is examined. The experimentally observed downstream stagnation and static pressure variation has shown significant flow modification in wide range of the flow Mach number (.5 – 2.). The voltage applied to the third electrode (“separator”) changes the observed discharge structure. The 2D time dependent numerical simulation can provide the qualitatively good correlation with the “averaged’ experimental data and not to be able to resolve the fine fast changing discharge structure.

Kinetic model of aluminum oxidation by water vapor in heterogeneous plasma: Gas-phase kinetics

A kinetic model of gas-phase and heterophase plasma-chemical processes taking place in a gas-discharge aluminum-water reactor with a pumping system is proposed. The model leads to a relatively simple system of equations that covers a great variety of reactions and offers an analytical solution for the composition of plasma with microparticles using experimental data. Along with the cycle of reactions typical for these heterogeneous mixtures, two more closed cycles of aluminum transformations are revealed in the plasma: atomic and molecular, generated by a stepwise ionization of Al and AlO by plasma electrons. The rate of aluminum oxidation and hydrogen formation through the molecular channel under the experimental conditions was comparable to the rate of heterogeneous processes. The inefficiency of the equilibrium oxidation mode is demonstrated.

Study of Structure and Dynamics of Enhanced Plasma Formations Created by Capillary Pulsed Discharge

The experimental researches on long-lived high-energetic enhanced plasmoid (LEP) creation by an erosive discharge have been carried out. The parameters of erosive discharge in a capillary with ablating walls are determined by high-current electric pulse and gas