Aleksey Bocharov

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

Numerical Simulation of the Discharge in Supersonic Flow Around a Sphere

ECENTLY the most common opinion on main physical mechanism responsible for aerodynamics effects resulted from electrical discharges created in airflow is that it is the heat release associated with Joule heating. The temperature increase changes the gas density, speed of sound, gas chemical composition and sometimes causes secondary shock and/or acoustic waves propagating away from the discharge area. Such a modification of flow parameters can result in significant change in local and integral gasdynamics characteristics of aerodynamics bodies in high-speed airflows. From the other hand, there are experimental observations which are difficult to explain only by effects of heat release

Constricted Discharge Interaction with High Speed Gas Flows

An objection of the work presented in current paper is to describe features of electrical discharge – gas flow interaction under external magnetic field and to discuss influence of the interaction on mixing and combustion of non-premixed streams of fuel and oxidizer. Theoretical, experimental and numerical results are presented in the paper. Different aspects of MHD assisted mixing and combustion of non-premixed high speed reacting flows are considered. Nomenclature V = reacting volume value S = contact surface area δdiff = diffusion layer thickness t = time

Study of Catalytic Effects at Reentry Vehicle

Two-dimensional simulations were performed with applications to surface heat flux mitigation by means of MHD interaction in hypersonic flow around a blunt body. The computational model realizes coupled solution of MHD chemically non-equilibrium irradiative airflow with taking into account heatand mass-transfer due to ablation of carbon from the surface. It was found that serious surface heat flux reduction is possible under conditions of MHD interaction even if additional radiative heating could be present due to increase of the shock layer thickness. It was also found that uncoupled flow/radiation treatment may lead to quite different estimations of MHD-assisted heat flux reduction.

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.

Non-Equilibrium Effects in MHD Parachute Concept. Induced Electric Field Effects

Recently the novel concept called MHD parachute has been presented. The idea is to effect on the reentry vehicle trajectory by means of MHD. Plasma behind the bow shock interacts with magnetic field generated by the built-in-body magnetic system. As a result, magnetic force, cross-product of plasma current and magnetic induction, is generated in plasma around the flown body directed mainly against the freestream flow. In turn, the plasma current interacts with current within magnetic system so that the plasma flow “attracts” the body and the body decelerates too. It has been numerically shown that electromagnetic drag could be one order of magnitude more than hydrodynamic one. It has also been shown that neither angle-of-attack nor shape of the body influence the flight at magnetic field induction of order of 1-2Tesla. Those preliminary results were obtained with simplified flow model, which just takes into account the ionization of air behind the bow shock. The flow model is suitable for ground-based facilities rather than real flight conditions. In the current paper the MHD parachute in real airflow is numerically studied. Namely, Ma=25 thermochemical non-equilibrium flow around the wing-like body is considered. New aspects of real airflow are discussed related with possible ionization due to strong induced electric fields. Also preliminary experimental results on testing the possibility of new effects under conditions of on-ground MHD facility are discussed.

On Efficiency of Heat Flux Mitigation by The Magnetic Field In MHD Re-Entry Flow

More than 50 years MHD flow control is the subject of intensive studies. As far as aerospace application is concerned, its potential could be utilized through, for instance, mitigation of heat loads on the spacecraft surface while re-entry path. The feasibility of heat flux mitigation was shown in many studies to associate with increase of bow shock stand-off distance, and, consequently, decrease of the mean temperature gradient across the shock layer. This can be characterized as direct MHD effect due to electromagnetic forces acting in ionized gas behind a strong shock. Another feasibility of heat flux mitigation proposed recently also utilizes action of electromagnetic force, but the primary goal of the idea is to decelerate the vehicle before it comes into thermally dangerous atmosphere [1-3,7,8]. In the current paper some aspects of electromagnetic heat flux mitigation are considered on the example of Stardust re-entry capsule flight path. The influence of the dipole-like magnetic field is investigated for free-stream conditions corresponding to altitudes from 81 km to 55 km of entry path. MHD flow is numerically studied with 11 species air chemistry model. Effects of the induced magnetic field are taken into account.

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.

Numerical simulation of electromagnetic wave propagation through the shock layer around a blunt-nosed body

Preliminary results of numerical simulation of the passage of an electromagnetic wave through the ionized shock layer around a blunt-nosed body in a hypersonic flow are presented. For calculation of the electromagnetic field, a field of flow is used that is computed using the software package PlasmAero developed at the Joint Institute for High Temperatures, Russian Academy of Sciences. Solutions are presented for a few wavelengths and several angles of wave incidence. The electron concentration for the flow under study is shown to be too high near the nose of the streamlined body, which leads to a significant weakening of the electromagnetic field on the surface of the body. At the same time, the situation downstream does not look as hopeless from the point of view of signal attenuation.

Direct Current Discharge in Supersonic Flow

Abstract. In paper the numerical model of non-equilibrium discharge in the flow has been presented based on coupled solution of the Navier-Stokes equations and transport equations for charged particles. This model has been applied to simulate the flow around the spherical cathode reported earlier in experimental work. Conclusion has been drawn that discharge effects on the flow through a thermal mechanism, while electrostatic force appearing in the cathode space charge region is too small to influence the flow field. At the same time, serious discrepancies in the computed and experimental results were observed. It was assumed that these discrepancies are probably due to uncertainties in flow and geometry specifying. In the current paper an attempt is made to numerically simulate the discharge in the flow for which the free-stream conditions are well known (Ma = 3.2). Experimental studies on the discharge under consideration were reported in paper. The model developed in paper is used for simulations. Attention is paid to the influence of plasma on the supersonic flow. The influence of the discharge on the model’s drag is discussed.