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Features of the simulation of the thermodynamic and gasdynamic processes occurring in devices for reducing the noise level of a shot from a gun were considered. A simulation of large vortices in the nonstationary turbulent flow of powder gases in a muzzle noise reduction device with a silencer representing a shaped channel with several chambers, whose volumes decrease in the direction to the silencer outlet, has been performed. Results of qualitative and quantitative investigations of the initiation, development, and damping of the shock waves in the flow of powder gases, formed as a result of the firing of a shot made from a signal gun, are presented.

Possibilities for using general-purpose graphics processing units to simulate compressible gas flows are discussed. Consideration is given to different schemes of computation of flows through the faces of the flow control volume and to the features of their implementation on graphics processing units. A solution of a number of model problems of gas dynamics on graphics processing units is presented and consideration is given to approaches to optimization of the program code connected with the use of different types of memory. A comparison is made between the rates of counting on a graphics processing unit and a central processor using grids having different resolution capabilities and various difference schemes of computation of flows.

A numerical simulation of a nonstationary flow of a gas containing inert particle in a shock tube has been perfumed on the basis of the model of mutually penetrating continua, in which the gaseous and dispersed phases are defined by sets of mass, momentum, and energy conservation equations and the equation for the evolution of the dispersed-phase volume fraction. The main equations are hyperbolic, and they are solved using the Godunov-type method of increased accuracy. The shock-wave structure of the gas flow in the working section of the shock tube and the space and time dependences of this flow were determined. The numerical-simulation results are compared with available experimental and calculation data.

The influence of the geometric and regime parameters of a resonance infrared jet-edge generator on the formation, in its resonance tube, of a sound field with a predominant discrete tone at the fundamental frequency of the generator resonant cavity was investigated. A parametric investigation of the self-sustained oscillation processes arising in the resonance tube of the generator as a result of the interaction of a subsonic gas jet and a supersonic one with its resonant cavity has been performed. The nonstationary structure of the gas flow inside this cavity, characteristic of the self-sustained oscillation interaction of a gas jet with an obstacle, is discussed. Prominence is given to the study of the pattern of the gas flow inside the resonant cavity and the amplitude-frequency characteristics of the wave process in it. Recommendations for designing a resonance infrasound jet-edge generator with regard for its use in actual practice are given.

Problems on the development of mathematical models for control of the technological processes of producing powders of metals from their melts and for optimization of these processes were considered. A numerical simulation of the solidification of melt droplets in a turbulent cold-gas jet has been performed with the use of a complex mathematical model, and results of this simulation were used for estimating the influence of different factors on the flying of a melt droplet in a gas flow until it is solidified.

The design of a subsonic jet-edge rod generator of the Hartmann-type oscillator and a scheme of measuring its acoustic parameters are presented. In this generator, unlike the Hartmann oscillator, not a cylindrical gas jet but an annular gas jet, moving along the thin cylindrical rod positioned at the axis of the generator nozzle, is used. A parametric investigation of the gasdynamic and acoustic processes arising in the tubular cavity of such a generator as a result of the interaction of a subsonic gas jet with this cavity has been performed with consideration for the nonstationary structure of the gas flow in the generator cavity. Recommendations on the choice of the design of a jet-edge rod generator of acoustic radiation with regard for its practical application are given.

A simulation of a high-temperature air flow in a nozzle with a nonstationary local power supply has been performed. The thermodynamic processes in this flow were simulated using an approximate model of equilibrium air thermodynamics. Results of a numerical simulation of one-dimensional flows in nozzles with a moving powersupply zone, used in alternating-current plasma generators, are presented. On the basis of the numerical-simulation data obtained, the qualitative patterns of the gasdynamic and thermal processes proceeding in such a nozzle with a nonstationary power supply were analyzed. The results of calculations performed on the basis of the ideal-gas and real-gas models with regard for the physicochemical processes occurring in a real gas at a high temperature were compared.

The interaction of solid particles with vortex structures was investigated, and the scattering of such particles by a combined vortex was numerically simulated using the Euler–Lagrange approach. The concentration distributions of particles in the region of a gas flow occupied by a vortex at different instants of time have been obtained. The dependence of the time for which these particles escape from the central zone of the vortex on their size was determined. The results obtained can be used for increasing the efficiency of measurement of the parameters of the disperse phase in a fluid flow by optical methods.

The formation of regions with a higher concentration of solid particles in the completely developed turbulent flow in a channel with impermeable walls was investigated. A gas flow was simulated on the basis of nonstationary three-dimensional Navier–Stokes equations. The discrete-trajectory approach was used for simulation of the movement of particles. On the basis of the data of a direct numerical simulation, the distributions of the average and pulsating characteristics of the flow in the channel and the concentration distribution of the dispersed phase in it were determined. It was established that the formation of regions with a higher concentration of solid particles in the channel is due to the instantaneous redistribution of vorticity near its walls. The numerical-simulation data obtained are in qualitative and quantitative agreement with the corresponding results of physical and computational experiments.

A numerical simulation of a supersonic two-dimensional gas flow into which a gas jet is injected from the surface of a fl at plate along the normal to it has been performed. The calculations were carried out using the Reynolds-averaged Navier–Stokes equations closed by the SST model of turbulence. The influence of the pressure ratio of the jet on the structure of the flow formed as a result of its injection into the supersonic crossflow, the angle of inclination of the head shock wave, the length of the separation zone, and the depth of penetration of the jet into the main flow were determined. The results of calculations performed for different Mach numbers of the main flow and different pressure ratios of the injected jet were compared with the corresponding results of a physical experiment. The data obtained can be used for optimization of the mixing of the injected jet with the main supersonic crossflow.

The flow of combustion products containing condensed-phase particles over the recessed vectorable nozzle of a solid-propellant rocket motor was investigated with the use of the Reynolds-averaged Navier–Stokes equations, equations of the k–e model of turbulence, and the Lagrange approach. The fields of flows of combustion products and the mechanical trajectories of condensed-phase particles in the charge channel, the prenozzle space, and the nozzle unit of this motor were calculated for different angles of swing of the nozzle. The formation of vortices in the gas flow in the neighborhood of the downstream cover of the nozzle and their influence on the movement of particles different in size were considered.

Numerical simulation of gasdynamic processes accompanying the operation of the recessed nozzle of a solid-propellant rocket motor in its linear displacement is carried out. Reynolds-averaged Navier–Stokes equations closed using the equations of a k–e turbulence model are used for calculations. The calculations are done for different rates of flow of the gas in the main channel and in the over-nozzle gap, and also for different displacements of the nozzle from an axisymmetric position. The asymmetry of geometry gives rise to a complicated spatial flow pattern characterized by the presence of singular points of spreading and by substantially inhomogeneous velocity and pressure distributions. The vortex flow pattern resulting from the linear displacement of the nozzle from an axisymmetric position is compared with the data of experimental visualization. The change in the vortex pattern of the flow and in the position of the singular points as a function of the flow coefficient and the displacement of the nozzle from the symmetry axis is discussed.

Results of formation of a ferromagnetic τ-phase and an antiferromagnetic e-phase in alloys of type Mn54Al43C3 obtained by induction and arc melting and by rapid hardening of the melt are presented. The magnetic hysteresis properties of powders produced by high-power mechanical milling of the synthesized alloys are studied. The optimum temperature conditions for transformation of the e-phase into a ferromagnetic τ-phase are determined for the alloys and for their ultrafine powders. The resulting powders of Mn54Al43C3 have an ultimate specific magnetization σ m = 81 (G · cm3)/g and a coercive force H c = 3 kOe in a magnetic field of 12 kOe.

In experiments on mature male Wistar rats, the dynamics of morphological modifications of neurocytes of the hippocampal CA3 area after a severe thermal trauma were examined. The pattern and degree of morphofunctional changes in the nerve cells depended significantly on the time interval after thermal trauma; their intensity correlated with the stages of burn disease. At stages of acute shock and early toxemia (days 1 to 7), mostly effects that could be interpreted as adaptive/compensatory reactions were observed, although initial signs of destructive changes were also obvious. At stages of late toxemia and septicotoxemia (days 14 to 21), deep irreversible destructive modifications in a considerable part of neurocytes of the hippocampal CA3 area became appreciable. The proportions of neurocytes belonging to different morphological types and values of the nucleo-cytoplasmic ratio (NCR) in such cells changed significantly. After an experimental burn, the total density of neurocytes gradually decreased, while portions of sharply hypo- and hyperchromic cells, in which NCRs underwent maximum modifications, increased. Electron microscopy of CA3 nerve cell demonstrated the development of destructive changes in the nuclei and cytoplasmic structures (degranulation of the endoplasmic reticulum, decrease in the number of ribosomes and polysomes, hypertrophy of the mitochondria with clarification of their matrix and destruction of mitochondrial cristae, and increase in the number of lysosomes). Therefore, severe thermal trauma induces significant morphofunctional modifications of neurocytes in the hippocampal CA3 area.

A numerical simulation of the hydrodynamic effects arising in the process of work of the vectorable thrust nozzle of a solid-propellant rocket engine has been performed. The fields of the flows of combustion products in the channel of a charge, the prenozzle space, and the nozzle unit were calculated for different angles of vectoring of the nozzle. The distributions of the gasdynamic parameters of the flow of combustion products in the prenozzle space, corresponding to their efflux from the cylindrical and star-shaped channels of charges, were compared. The formation of a vortex flow in the neighborhood of the back cover of the nozzle was considered.

Detached-eddy simulation (DES) of turbulent flows of viscous incompressible fluid is performed based on unstructured meshes. The common finite-difference schemes for discretization of convective fluxes are applied, and the DES model constants are calibrated for each of the numerical schemes presented. Results computed with the DES model on various types of meshes (block-structured, tetrahedral and polyhedral unstructured meshes, as well as a mesh with triangular prismatic elements) are analyzed. Efficiency of the discretization schemes selected for DES calculations is compared for different meshes. Calculations are performed for some benchmark test cases, decaying homogeneous isotropic turbulence and flow behind a backward-facing step. Recommendations to the selection of model constants and properties of various meshes are given for the DES calculations of turbulent flows of viscous incompressible fluid.

Features of the technology used to make rail steel at the EVRAZ ZSMK combine are discussed along with the requirements on the steel’s contents of residual elements. A description is given of the step-by-step introduction of a process for sorting scrap to make rail steel, the sorting being based on the scrap’s content of residual elements. A comparative analysis is made of changes in the technical-economic indices of rail-steel production before and after the introduction of the sorting operation and the reasons for those changes are explained. The cost-effectiveness of the measures that were implemented is also evaluated.

Experimental studies are performed for determining the effect of hot rolling process parameters on structure formation and a set of mechanical properties for R65 type rails made from steel E78KhSF under EVRAZ ZSMK conditions. The effect of processing parameters of the existing production scheme (temperature-time, deformation rate and energy and force parameters) for production of R65 type rails made from steel E78KhSF is studied using a Gleeble System 3800 simulation unit.

Engineers and scientists in Russia and abroad are giving a considerable amount of attention to improving the quality of the rails being made by metallurgical plants. Rolling 100-m-long rails requires proper preheating of the continuous-cast semifinished products with a minimal temperature gradient along and across the products. A heating operation of the requisite quality is assured by the use of a level-2 automation system to heat the metal in the furnace.

Methods of transmission electron microscopy are used for layer-by-layer analysis of rails of the highest quality grade. Quantitative parameters of structure gradients, phase composition, and dislocation substructures formed by various mechanisms of γ–α transformation are determined. Sources of long-range stress fields are revealed. It is determined that possible places of microcrack origin in the steel are interfaces cementite particles – matrix.

UDC 532.529 Consideration is given to a number of issues associated with the application of a k–e turbulence model to description of flows in channels with permeable walls. The influence of such factors as the method of setting boundary conditions, compressibility, injection, and flow unsteadiness due to the forced pressure oscillations in the channel is evaluated on the basis of results of numerical modeling. The results of calculations within the framework of Reynolds-averaged Navier–Stokes equations are compared to the data based on the simulation of large eddies of turbulent flow in a channel with injection. Conclusions on the possibility of applying a k–e turbulence model to calculation of flows formed by injection are drawn.

A semi-empirical model is developed to study distortions of the phase function of a coherent beam, which are induced by turbulent fluctuations of flow parameters. Large eddy simulations of the boundary-layer and mixing-layer flows and also of related aero-optical effects are performed. Results of numerical calculations are compared with results of physical experiments and with data obtained by solving the Reynolds-averaged Navier—Stokes equations.

Numerical simulation of turbulent flows of a gas suspension in the vicinity of the critical point and in a channel with permeable walls has been carried out. The influence of the concentration of the dispersed phase and the size of its particles on the distribution of mean and pulsation characteristics of the flow, as well as on the friction and heat transfer coefficients, is discussed.

The motion and heat and mass transfer of particles of a disperse admixture in nonisothermal jets of a gas and a low-temperature plasma are simulated with allowance for the migration mechanism of particle motion actuated by the turbophoresis force and the influence of turbulent fluctuations of the jet flow velocity on heat and mass transfer of the particle. The temperature distribution inside the particle at each time step is found by solving the equation of unsteady heat conduction. The laws of scattering of the admixture and the laws of melting and evaporation of an individual particle are studied, depending on the injection velocity and on the method of particle insertion into the jet flow. The calculated results are compared with data obtained with ignored influence of turbulent fluctuations on the motion and heat and mass transfer of the disperse phase.

Modeling of a turbulent flow in a cylindrical solid propellant charge channel having a circular recess (compensator) has been performed. Different variants of the compensator position and connection to the channel are discussed. The influence of the geometric and consumption factors on the formation of distributions of the gas-dynamic parameters and characteristics of turbulence in the working region has been investigated.

The influence of the chemical reactions occurring in the gas phase of a gas suspension flowing in a channel with penetrable walls and the combustion of the condensed-impurity particles in this flow on its gasdynamic structure has been investigated. It is shown that the order of the system of equations defining a flow of a chemically reactive gas suspension with a homogeneous exothermic reaction proceeding at a definite rate and a heterogeneous combustion of the condensed-phase particles can be decreased if certain assumptions are mode. The distributions of the parameters of the gas and dispersed phases were calculated as functions of the rate of blow and the sizes of the particles.

This paper considers issues connected with the construction and numerical realization of stochastic models of motion and scattering of condensed impurity particles in a turbulent flow based on the integration of a Langevin-type equation. The proposed model is used to calculate the turbulent flow of a low-concentration gas suspension in a channel with permeable walls. Calculations are performed for various values of the injection rate, sizes of particles, and the conditions of their introduction into the channel.

Problems related to modeling of the motion of discrete inclusions (solid particles, drops or bubbles) in flows with concentrated vorticity are considered. A comparative evaluation of the force factors in the equation of motion of a test particle is made. The results of numerical modeling of the motion of discrete inclusions in the gap between concentric rotating cylinders and a vortex flow formed by the liquid rotating with a constant angular velocity over a fixed base are discussed. The coordinates of the points of equilibrium of the test particle in the vortex flow are found.

The characteristic features of the formulation of a two-layer turbulence model and its application in calculation of near-wall turbulent flows are considered. Factors that influence the effectiveness of implementation of the model and ways of expanding the limits of its applicability are discussed. The possibilities of the two-layer model are demonstrated by calculating a boundary layer on a flat plate with a longitudinal pressure gradient. A comparison of the results of calculation of the heat-transfer characteristics by the two-layer model, two-parameter dissipation model, and Spalart-Allmaras model with the data of a physical experiment and available correlations is made.

Large eddy simulations are performed for an unsteady flow and heat transfer in the region of interaction of a circular turbulent jet with a normally positioned flat obstacle (target). Space-filtered Navier-Stokes equations are closed by the RNG model of eddy viscosity, which takes into account the curvature of streamlines in the region of flow turning. The computations are performed for different dimensionless distances between the nozzle exit and the target and for different Reynolds numbers. The dependence between the Nusselt number distribution over the target surface and the vortex structure of the jet is analyzed. The local and integral characteristics of the flow are compared with the data of a physical experiment.

Velocity and concentration distributions of the condensed phase have been obtained based on the parameter-expansion method. The characteristics of two-phase flows in channels with strong and weak injections have been investigated. The factors exerting an influence on the velocity of nonequilibrium phase motion have been determined; the range of applicability of the solution obtained has been established and its qualitative behavior has been elucidated; the possibility of applying such a solution to calculation of the concentration of the condensed phase has been shown.

Flows in the channels of solid-fuel charges with cross sections having different views in plan and flows in the prenozzle volume and the nozzle unit of a solid-fuel rocket engine have been simulated on the basis of the STAR-CD suite for different types of charges and different designs of the input part of the engine nozzle. The influence of the compressibility, turbulence, geometric factors, and flow rate on the distributions of gasdynamic parameters in the working region of the engine has been investigated.

The accuracy and computational efficiency are compared for a number of models of subgrid eddy viscosity (Smagorinsky model, renormalization group model, and dynamic and one-parameter models). Space-filtered Navier-Stokes equations are solved numerically by the control-volume approach on a nonuniform grid with the use of high-resolution schemes in time and space. The numerical data are compared with the results of a physical experiment and direct numerical simulation.

The effect of longitudinal pressure gradient and localized injection on turbulent heat transfer on a flat plate is treated. The variation of the flow pattern, characteristics of heat transfer, and the efficiency of cooling the plate are investigated depending on the magnitude and sign of the pressure gradient and on the parameters of injection. The calculation results obtained using different models of turbulence are compared with data of physical experiment and available correlations.

The mechanisms of formation of three-dimensional jet flows inside large-scale vortex structures in a closed cubic cavity have been considered. The vortex structure of an incompressible viscous-fluid flow in this cavity has been investigated using the qualitative theory of ordinary differential equations. Singular points and their types and positions were determined at different Reynolds numbers on the basis of numerical calculations.

The bifurcation of the lines of a viscous-fluid flow in a rectangular cavity with a moving cover has been investigated for different ratios between the sides of the cavity and different Reynolds numbers on the basis of the qualitative theory of dynamic systems. The critical parameters of the problem, at which the type of singular points changes, and other topological characteristics of a vortex flow in the indicated cavity have been determined and the corresponding bifurcation diagrams have been constructed.

A turbulent flow in a closed axisymmetric cavity with a rotating disk is considered. The moment of resistance to disk rotation is calculated as a function of the dimensionless gap between the motionless casing and rotating disk and of the Reynolds number. Results calculated on the basis of different turbulence models are compared with data of a physical experiment and with available correlations.

Consideration is given to problems associated with modeling of the motion of a condensed particle in a channel with injection with allowance for the action of different force factors (the hydrodynamic-drag force, the Saffman lift force, and the thermophoresis force). From the results of the numerical modeling, the author draws conclusions on the degree of influence of different force factors on the pattern of motion of the particle.

A facultative halophite Mesembryanthemum crystallinum L. (the common ice plant) was shown to grow successively at the high concentrations of Cu and Zn. Although 25 µM CuSO4 or 800 µM ZnSO4 retarded markedly plant growth, they did not interfere with the completion of plant development and the formation of viable seeds. In such plants, leaves accumulated more than 200 µg of Cu and 1700 µg of Zn per 1 g of dry weight. A damaging effect of heavy metals (HMs) was manifested in a reduced content of water in leaves and proline accumulation in them. As copper is a metal with transient valence, copper salts are more toxic than zinc salts, which was manifested in a stronger inhibition of the chlorophyll synthesis. Both HMs induced oxidative stress, as evident from increased activities of guaiacol peroxidase and lipoxygenase. Moderate Cu and Zn concentrations did not damage cell membranes in leaves, as evident from the absence of their action on electrolyte leakage either under optimum conditions or after heat treatment. A capability of a substantial HM accumulation by the common ice plant and their considerable transport to shoots (up to 50 µg of Cu and 560 µg of Zn per plant) make it possible to consider the common ice plant as a promising phytoremediator.

On the basis of the thermal approach, a mathematical model of the optical breakdown on condensed inclusions exposed to pulsed laser radiation is developed. As individual stages of the process, we consider the particle heating and evaporation, the formation of a vapor aureole and its ionization, as well as the propagation of shock waves in the space surrounding the particle. The threshold characteristics of the laser-beam parameters sufficient for initiating an optical breakdown on metal and dielectric particles, as well as on dielectric liquid drops are determined.

A mathematical model is developed of optical breakdown on droplets of dielectric liquid under the effect of pulsed laser radiation. The heating and evaporation of a particle, and the generation of a vapor halo and its ionization, as well as the propagation of shock waves in the space surrounding the particle, are treated as separate stages of the process. The threshold characteristics of the laser beam parameters are determined, which are sufficient for the initiation of optical breakdown on droplets of dielectric liquid. The dependence of the threshold power of optical breakdown on the size of laser spot is calculated.