The example of a model reaction of combustion of hydrogen with oxygen is used to show that the flame propagation rate, its thermal mode, and conditions for transition to an explosion strongly depend on the rate of heterogeneous reactions of free atoms and radicals. There is a correlation between the efficiency of heterogeneous termination of reaction chains and the flame propagation rate. The reactions of atoms and radicals on the surface also largely determine the concentration and temperature gradients in the flame. It was discovered that a flame has a strong effect on the chemical properties of the surface and its role in combustion.

The results of an experimental study of an alternating current discharge with a frequency of 50 Hz in a gas-liquid medium of a 1

This paper deals with the optimization criteria, mathematical model, and calculation results for the mixing of flows in a model combustion chamber with different configurations for the system of injecting the gasification products of power condenced composition. Gasification products represent a mixture of gas and condensed phases. The earlier developed data processing algorithm is improved by introducing a probabilistic approach into the trajectory estimation of the distribution of disperse phase particles in the cross sections of a model combustion chamber of small length. As a result of the performed parametric studies, some recommendations are proposed to improve the quality of mixing the gasification products with the air flow in a model combustion chamber and minimize the effect of condensed phase particles on the walls of the flow duct of a combustion chamber. The results of these studies can be used for the development of recommendations on how to provide the performability and improve the efficiency of the working process in promising power plants.

The article presents a physical picture of electrical processes in the atmosphere, based on atmospheric measurements and physical laws. Some processes of atmospheric electricity associated with water microdroplets in the atmosphere are analyzed. It is shown that microdroplets acquire a charge in their growth process, and the loss of charge by microdroplets, which occurs at the lower boundary of a cumulus cloud, leads to breakdown in the form of lightning, accompanied by rapid (within minutes) aggregation of cumulus cloud microdroplets into raindrops. Representing the electrical processes in the atmosphere as secondary with respect to water circulation through the atmosphere, we find that water condensation in the atmosphere results from the mixing of moist the near-surface air layers with cold air at altitudes of several kilometers under vertical wind action. The dominant droplet growth mechanisms are coalescence for small droplets and gravitational fall for large droplets. In this case, equilibrium between cumulus cloud water microdroplets and saturated vapor of free molecules is established in a fraction of a second; i.e., this equilibrium is maintained during the evolution of the cumulus cloud. This means that the water vapor inside the cumulus cloud is saturated. The droplet charging mechanism is similar to this process in plasma and is governed by the varying mobility of positive and negative ions in atmospheric air, while the ions themselves in it form under the action of cosmic rays. Atmospheric water microdroplets are also a greenhouse component of the atmosphere. Analysis of the thermal radiation of atmospheric water microdroplets, in addition to the energy balance of the Earth and atmosphere, makes it possible to estimate the fraction of condensed water in the atmosphere, the mass of which is a fraction of a percent of the mass of atmospheric water vapor in the form of free water molecules. At the same time, clouds are a heterogeneous medium, so that areas in the atmosphere containing water microdroplets exist in the atmosphere as separate clusters. Although analysis of the water microdroplet behavior in cumulus clouds allows us to answer certain questions on the physics of atmospheric electricity, other aspects of this problem retain a schematic character and require further study.

The equation of state for a degenerate electron gas is derived in an explicit form from the Fermi–Dirac distribution due to analytical expansions in terms of the degeneracy parameter. A direct computer calculation is performed with the exact integral formulas of the Fermi−Dirac distribution so that to confirm the analytical approximations obtained. Practical formulas for the equation of state and chemical potential for degenerate electron gas are recommended.

A high-frequency discharge ( f = 13.56 MHz) generated between jet electrolytic (3% solution of ammonium sulfate in purified water) and metal (copper plates of the M1 grade) electrodes in the pressure range of p = 105–3 × 104 Pa is studied. The ignition of the high-frequency (HF) discharge was carried out by applying an electrolyte jet to the surface of a copper plate in the discharge chamber. The types and shapes of plasma structures generated in the interelectrode gap and their mutual transformations at the change in the voltage are considered. Hydrogasdynamic processes in the combustion zone of the HF discharge are described, including optically inhomogeneous gas flows, disturbances of the jet electrode, and the formation of droplets. The thermograms of the surface of the jet and metal electrodes under the conditions of the HF discharge combustion are considered. The composition of the plasma, the electron density, and the temperature of the heavy component are studied using emission spectroscopy.

The results of an experimental study of an alternating current discharge with a frequency of 50 Hz in a gas-liquid medium of a 1% of NaCl solution in distilled water with air bubbles and microdischarges inside a dielectric tube with a diameter of 10 mm at reduced pressures for various interelectrode distances of copper electrodes—50, 100, and 150 mm—are presented. A qualitative mechanism for the development of a breakdown and discharge at low pressures in a gas-liquid medium is established. It is found that with a decrease in pressure, a gas-liquid medium is formed, saturated with small air bubbles ranging in size from 1 to 3 mm as a result of boiling and electrolysis. This, in turn, leads to a breakdown and rapid discharge ignition in a porous medium near a solid electrode. The transition of an electric discharge with microdischarges to a volumetric discharge at low pressures is established. A fast Fourier transform was carried out, and the discharge voltage and current spectra were determined at reduced pressures.

The Gordon method for the generation of metal nanowires in superfluid helium as a result of the laser evaporation of a metal surface that is contiguous with superfluid helium has been analyzed. The cluster stage of the process, in which a beam of evaporated metal atoms is transformed into a gas of metal clusters so that further relaxation of the evaporated metal is due to radiation by metal clusters, is considered. These processes are experimentally compared for the case in which a beam of evaporated tungsten atoms is fed into superfluid helium, a vacuum, and helium gas. Since the relaxation process in this stage runs at a temperature of several thousands of kelvin in the region of the cluster presence, the radiative mechanism of cluster cooling is similar in the considered cases; however, for superfluid and normal helium, a significant contribution to the cooling rate is from the heat transfer in helium. It follows from the experiment that the next stage of evaporated metal relaxation in superfluid helium includes the division of the metal-containing region into many small regions bounded by individual vortices. Each vortex captures a large number of clusters that move to the axis of this vortex and are aggregated therein. This leads to the formation of metal nanowires with a length that is about two orders of magnitude larger than their radius. These nanowires comprise a special physical object of both fundamental and practical importance.

The paper studies experimentally the stability of an inverted conical plane-symmetrical premixed methane-air flame under normal and reversed gravity. The conical flame is stabilized by a thin transverse rod. Flow velocity is varied within the range of 1–8 m/s, fuel equivalence ratio— within the range of 0.8–1.4. It is shown that such a flame could be both V-shaped (attached only to the stabilization rod) and M-shaped (attached both to nozzle edge and stabilization rod) depending on the set of conditions. The transition between two modes is studied experimentally under normal and reversed gravity. The hysteresis properties for the M–V and V–M transitions under the normal gravity conditions and their absence under the reverse gravity ones are reported. The most unstable flames are observed under reversed gravity at the maximum burning velocity (φ ≈ 1.1 ±). For such conditions, periodical oscillations between M-shaped and V-shaped flames occur over a wide range of velocities. In the experiments under reverse gravity, the V shape prevails over the M shape. It is found that a reverse flow exists above the stabilizer at any velocity under normal gravity and at high velocities (>5 m/s) under reverse gravity. In both cases, a linear increase in the longitudinal size of the vortex zone with increasing velocity is observed. It is concluded that gravity noticeably contributes to rich flames stability.

The review contains a description of modern methods and results of designing new materials for nuclear energy applications. The first part presented in this review contains a description of ab initio methods for calculating of materials properties. It describes rigorous and approximate quantum methods (density functional method) for the predicting the properties of materials employing modern supercomputers, and popular software packages for numerical simulation, as well as databases of first-principles calculations that exist internationally. With the accumulation of a large number of laborious quantum calculations, artificial intelligence methods are becoming more and more effective. In particular, machine learning methods are considered, and results of their use for the design of materials are presented in the review. The results of quantum mechanics modeling of binary alloys of iron, chromium and nickel are presented. The second part of the review will be devoted to quantum modeling of liquid and plasma states of matter in reactors, as well as experimental studies of materials for nuclear power. The third part of the review will be devoted to non-equilibrium plasma formed in reactors as a result of secondary processes during stopping of fast particles.

This paper considers the problem of a thin shear layer evolution at Reynolds number rmRe = 400000 using the novel Compact Accurately Boundary Adjusting high-Resolution Technique (CABARET). The study is focused on the effect of the specific mesh refinement in the high shear rate areas on the flow properties under the influence of the developing instability. The original sequence of computational meshes (256 2 , 512 2 , 1024 2 , 2048 2 cells) is modified using an iterative refinement algorithm based on the hyperbolic tangent. The properties of the solutions obtained are discussed in terms of the initial momentum thickness and the initial vorticity thickness, viscous and dilatational dissipation rates and also integral enstrophy. The growth rate for the most unstable mode depending on the mesh resolution is considered. In conclusion the accuracy of calculated mesh functions is estimated via L 1 , L 2 , L ∞ norms.

Low-temperature plasma is used in metallurgy for steel alloying by nitrogen, deoxidization of magnetic alloys, obtaining of steels with particularly low carbon content, metal cleaning of nonmetallic inclusions, desulfurization and other refining processes. The wide application of those technologies is restrained by absence of reliable generators of low-temperature plasma (GLP) with sufficient resource of continuous operation. As a result of studies, a universal generator of high-enthalpy plasma jet of various working gases was created. The generator has expanding channel of the output electrode with an efficiency of ~60 % for argon working gas and ~80% for nitrogen and air. It was shown that the developed generator of low-temperature plasma ensures formation of a weakly diverging (2α = 12°) plasma jet with a diameter D = 5–12 mm, an enthalpy of 5–50 kJ/g and a mass average temperature of 5–10 kK, at a full electric power of the arc discharge of 5–50 kW and a plasma-forming gas flow rate of 1–3 g/s. Results of the study of propane additions to the plasma-forming gas effect on the state of cathodes with inserts made of pure tungsten, lanthanum tungsten, and hafnium presented. It was shown that a small propane addition (1%) to the plasma-forming gas, results in reducing effect of the insert material. Study of the GLP operation at arc current 100A with addition to the working gas nitrogen maximum possible volume of propane, which don’t disturb stability of arc showed that for the developed plasma generator at the nitrogen flow rate ~0,45 g/s, the propane flow rate was ~0,33 g/s (not more than ~73 % of the plasma-forming gas). The created high-resource GLP with changeable electrodes enables to obtain at the exit a high-enthalpy plasma flow of various gases (argon, nitrogen, air) and can be a prototype of more powerful plasmotrons of various technological application, in particular for plasma metallurgy.

The methods and results of the modeling of explosions and the kinetics of the stress-strain state of high-voltage, oil-filled electrical equipment are presented on the example of the destruction of high-voltage, oil-filled transformers in the event of a short circuit. The theory, methods, and developed modules in the Flow Vision and Gas Dynamic Tool (GDT) packages and the pairing of the ANSYS and LS DYNA packages are described. The physical and mathematical models underlying the developed approaches, computational schemes, and packet interfaces are described. A comparison with the experimental results is made.

To study the thermophysical, electrophysical and optical properties of argon, as well as the implementation of various plasma-chemical reactions, a direct-current generator of a high-enthalpy argon plasma jet with a self-adjusting arc length and an expanding channel of the output electrode has been developed. A comparative analysis of the electrophysical characteristics (current–voltage characteristics—CVC, efficiency) in the expanding and cylindrical channels of constant cross section was carried out. Electrical, calorimetric and spectral studies have shown that the created generator of low-temperature plasma provides the formation of a slightly divergent plasma jet of argon with a diameter of 5–8 × 10–3 m and enthalpy of 5–10 MJ/kg and a mass-average temperature at the outlet of the gas-discharge channel of 5–12 × 103 K with an electron concentration in the axial plasma of 1017 cm–3, the total electric power of the arc discharge 2–10 kW and the plasma-forming gas consumption rate of 1.5–3 × 10–3 kg/s. Depending on the initial conditions at a distance of 0–3 × 10–2 m from the nozzle section of the low-temperature plasma generator, the plasma flow velocity varies from 990 to 300 m/s.

Numerical simulation of laminar heat transfer enhancement at the hydrodynamic stabilization length of the tube with 8 inclined longitudinal oval-trench dimples (OTDs) in the transformer oil flow has revealed an optimal inclination angle of dimples, at which a value of thermal and hydraulic performance (THP) is achieved. Heat transfer of a dimpled tube increases by a factor of 28 in comparison with a smooth tube at practically invariable hydraulic losses. Heat transfer enhancement is calculated in turbulent air flow around a flat plate with a package of 16 one-row dimples inclined at an angle of 60° on the longitudinal section of 40 in length and 4 in width under the symmetry conditions at the side boundaries of the plate section and at a dimple step of 2.4. The dimple is 1 in width, 4.5 in length, and 0.2 in depth. Its rounding radius is 0.3. The boundary layer thickness at the section inlet is 0.175. The effect of abnormal separated flow intensification and heat transfer enhancement in dimples has been confirmed. ( f/f pl ) min =-3, (Nu/Nu pl ) max = 4. Relative heat transfer grows by a factor of 1.43 in comparison with the smooth plate and the drag coefficient increases by a factor of 2.08. However the thermal and hydraulic performance defined in terms of heat load growth is 1.12.