Valentin Bityurin

MHD electrical power generation in a T-layer plasma flow

In the present work, magnetohydrodynamics (MHD) power generation based on the T-layer regime has been investigated both experimentally and numerically. The experimental investigation has been carried out in a shock tunnel MHD facility. There, the plasma layer characteristics have been studied. The layers have been produced by means of electrical discharges at the entrance of a segmented Faraday MHD channel. Streak photography pictures and charge coupled device (CCD) camera snap shots are used to observe the layers. The effect of the layers on the local electrical power production is studied through the response of the currents of individual electrode pairs. The performance characteristic of the T-layer MHD generation has been investigated in a channel of commercial size (active length of 14 m) by means of numerical simulations performed by means of a two-dimensional time dependent (2-Dt) model. In the commercial size channel, when using ideal gas and neglecting loss mechanisms, an enthalpy extraction larger than 30% has been obtained. The effects of a real gas and of loss mechanisms on the T-layer MHD conversion have been studied by means of the 2-Dt numerical analysis in a 4-m channel. In this channel, when an ideal gas is used, a reduction of about 20% of the electrical power output is caused by the loss mechanisms. When loss mechanisms and combustion gas in the 4-m channel are considered, an increase of the power stored in the plasma T-layer is observed. This power is of the order of the electrical power extracted from the MHD channel.

Simulation of Naphthalene Conversion in Biogas Initiated by Pulsed Corona Discharges

The numerical results on naphthalene removal in biogas are presented and compared with experiment. Plasma-chemical processes in discharge and post discharge stages are considered. The self-consistent approach for modeling of cleaning process on the basis of pulsed corona discharges is demonstrated. It has been revealed that the reaction of naphthalene (C₁₀H₈) with excited nitrogen molecule (N₂(A³Sigma)) is very important in the cleaning process in nitrogen-containing mixtures. The addition to N₂ of CO, CO₂, and H₂ results in the deterioration of treatment.

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

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.

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

High enthalpy extraction numerical experiment in a plasma vane MHD generator

A numerical experiment in a plasma vane (current carrying plasma nonuniformity) MHD generator is presented. The numerical calculations are based on a time-dependent two-dimensional model. The gas constituting the plasma is assumed to be ideal. Viscosity and heat losses are neglected. In order to optimize the generator performance, a parametric analysis is carried out. The results of the calculations indicate that enthalpy extractions larger than 30% can be obtained. >

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.

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.

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.