Home – Home – Jornals – Scientific journal “Vestnik NSUEM” 2013 number 3

The article discusses issues of the development of Siberian region; comparative analysis of changes in socio-economic situation of Siberian Federal District1 and a number of leading Siberian territories in the last 20 years is carried out. Two groups of indicators are analyzed. They reflect significant characteristics of the level of economic and social development of Siberian regions: economic (gross regional product, export products volume, volumes of fixed asset formation; volumes of internal costs of research and development), social indicators (population size, per capita income level, poverty level and several others); data of government statistics was used as data base; conclusions are drawn and recommendations are made.

The article is analyzing anthropological trends from the point of view of the theories of development. In the article some theories of development are presented, which allow to investigate into different considerations about the theory of «the future». In the frame of these considerations the method of the work with the images of future is proposed in the form of the Foresight as the practice of the construction of future images.

A theoretical study of the equilibrium velocity of sound in the liquid-vapor mixture containing the close-packed layer of spherical particles has been carried out. Thermodynamic relations include a description of a non-stationary heat transfer between the mixture and particles in compression half-wave. The theoretical model allows explaining the experimentally observed significant reduction in the equilibrium velocity from its adiabatic value at the increase in vapor content of the mixture. The calculated results agree with experimental data obtained in the vertical channel at filtering the liquid-vapor mixture in a close-packed layer of spherical particles of borosilicate glass and steel.

Results of numerical simulation of warm gas injection into a porous medium initially saturated with gas and gas hydrate, accompanied by gas hydrate dissociation, are presented. It is shown that depending on parameters at the outer boundary of the medium (permeable or impermeable to the gas flow) hydrate dissociation can occur both at the frontal boundary and in the extended region.

Wollastonite synthesis and decomposition were analyzed from the viewpoint of thermodynamics (using the TERRA software). It is shown that wollastonite synthesis from limestone and silica takes place at a minimum content of nitrogen (10^–5 N₂) with a release of carbon dioxide. The synthesis temperature is Т ≥ 560 K. Wollastonite is decomposed in the presence of flue gas (4N2) with limestone and silica formation and burial of carbon dioxide in the form of CaCO3(c). Wollastonite decomposition temperature is Т ≤ 420 K. The cyclic reciprocating process for complete removal of carbon dioxide by wollastonite is suggested. Four strokes of the reciprocating system with the fixed temperatures of wollastonite decomposition (Т = 300 K) and wollastonite synthesis (Т = 560 K) are presented. Total energy consumption (Т = 560 K) is ΔI ≈ 130 kJ/mole, 30 % of energy is spent for heating and 70 % of energy is spent for chemical reaction. This is comparable with the heat of СО₂ solution in ethanolamin.

Normal impingement of a vortex ring, formed in water and transporting the coloring admixture, on a solid surface was studied experimentally. The size and shape of a trace of vortex impingement on the surface were determined. It was found that the size of trace does not depend on the speed of the vortex ring, and its shape is determined by the amount of admixture in the vortex. The connection of results with possible mechanism of annular structures formation on the ice of Lake Baikal is discussed.

The article presents the results of investigation of thermal expansion of ChS-139 steel in the temperature range 20–720 °С. Measurements were carried out by dilatometric method with DIL-402C unit manufactured by NETZSCH (Germany) with the error (1.5–2) × 10^–7 K^–1. The approximation dependences of thermal coefficient of linear expansion on temperature have been obtained and reference tables have been calculated. The abnormal change of expansion coefficient above 550 °С is shown, and the explanation of the phenomenon is given.

The system for PIV measurements in the flow with superimposed pulsations of the fluid (air) has been developed. Measurements of velocity and vorticity fields in a smooth duct in certain phases of superimposed pulsations have been performed. Statistics of a turbulent pulsating flow: velocity profiles, turbulent pulsations, and Reynolds stresses has been obtained.

A model to describe the heating of metal inclusions in inert media by a laser radiation pulse with allowance for the heat-transfer and melting processes in the matrix and inclusion materials is proposed. The time regularities of the heating of the matrix and inclusions were examined, and the dependences of the maximum temperature on the particle surface on the laser pulse energy density and on the particle radius were obtained. Approximate formulae for the maximum heating temperature and for the radius of most heated particles are proposed. We show that melting processes result in a reduction of the maximum heating temperature and in an insignificant variation of the radius of most heated particles.

The work deals with the obtaining by the vacuum gas-jet technique of the metal-polymer composites consisting of silver nanoparticles introduced into a fluorocarbon polymer matrix and the investigation of their optical properties. The dependence of the optical density in the visible range of frequencies on the structure of obtained samples has been investigated. The obtained composites are found to possess the plasmon resonance effect.

A physical and mathematical model is proposed, which is based on the Smolukhovsky’s equation describing the dynamics of the variation of the distribution function of aerosol particles over their sizes with regard for ultrasonic action, evaporation (for liquid-drop aerosols), and sedimentation. The expressions are obtained for the coagulation kinetics depending on the main parameters of action, the properties of aerosol and medium: the concentration and dispersion composition of the original aerosol, viscosity and temperature of the medium, physical-chemical parameters of particles material. Computational results obtained by using the proposed model correspond to experimental data.

The differential variation of the method of capillary rise was used to measure the capillary con-stant and to determine the surface tension of ethane-methane solution at “high” temperatures. Measurements were performed on the isotherms in the range of temperatures 213.15 ÷ 283.15 K at pressures up to 4 MPa. Decrease of ethane surface tension with the increase of pressure and concentration of methane in the solution is shown. The experimental data are compared with the results of surface tension calculation according to Rowlinson theory. Methane adsorption in the interface layer of solution is calculated.

Results of experimental investigation of heat transfer and wall friction in the upward bubble flow in a flat inclined channel are presented. Measurements were carried out in the range of superfi-cial liquid velocities of 0.3–1.1 m/s and different values of volumetric void fraction. The hydrodynamic structure was measured by means of the electrochemical method with the use of miniature friction sensors. The values of average friction and heat transfer at different channel orientation were determined. It is shown that in the bubble gas-liquid flow we can observe a significant dependence of friction and heat transfer on the angle of channel inclination.

Мethods of measuring lifetime and continuous pressure decrease were used to study kinetics of spontaneous boiling-up of superheated ethane-methane solutions. The attainable superheats of solutions at two pressure values (1.0 and 1.6 MPa) and two concentrations of methane (2.1 and 6.0 mole %) were determined experimentally in the range of nucleation rate J = 1∙10⁴–3∙10⁸ s^–1m^–3. At temperatures 266.5, 270.0, and 273.15 K, the attainable stretching of the studied solutions was measured. The experimental results were compared with the theory of homogeneous nucleation. At nucleation rates J ≥ 2.5∙10⁶ s^–1m^–3, there is a fair agreement of the theory and experiment. The discrepancy in attainable superheat temperatures Tn does not exceed 0.8 K. It is shown that significant underheating of solution to theoretical values Tn at J < 2.5∙10⁶ s^–1m^–3 cannot be bound only with heterogeneous nucleation but is conditioned by other factors as well.

The method of penetrating gamma-radiation was used to measure the density of copper-aluminum melts containing from 0 to 100 % aluminum in the range of temperatures from liquidus to 1300–1400 ºС; the concentration dependences of their molar volume were calculated as well. High accuracy of measurements (error not exceeding 0.2 %) allows using the values as reference data. Substantial non-monotonicity of the molar volume isotherms that proves the complexity of the specified melts especially in the area of compositions rich in aluminum was found. The parameters of polynomials describing concentration dependencies of the molar volume with the error not exceeding 1 % are presented.

A numerical analysis of the unsteady regimes of the natural convection and thermal radiation in a square enclosure with heat-conducting walls has been carried out in the presence of a heat source of finite sizes located in the base zone under the conditions of convective exchange with the ambient medium. The mathematical model formulated in the dimensionless variables “stream function — vorticity — temperature” has been implemented numerically by a finite difference method. The influence of the reduced emissivity of internal surfaces of bounding walls on the local characteristics (the streamlines and temperature fields) and on the integral complex (the mean Nusselt number on typical boundaries) has been analyzed in detail for 0 ≤ ε < 1, the location of the heat source 0.1 ≤ l/L ≤ 0.4, and its length 0.2 ≤ l_hs/L ≤ 0.6 for Ra = 10⁶, Pr = 0.7. The approximation relations have been derived for the mean convective and radiation Nusselt numbers depending on the reduced emissivity of the internal surfaces of bounding walls and the energy source location relative to vertical walls.

The analysis of energy balance equation for viscous laminar flow of fluid or gas in the cylindrical channel in the area (zone) of warm-up bounded along the longitudinal coordinate is made. It was found that at laminar flow of fluid or gas in a round pipe, in each warm-up area bounded along the longitudinal coordinate there are the areas of direct and reverse flows separated by a plane that is a locus of points where temperature is maximal for each fixed value of radial coordinate r.

It is shown that with an increase in elasticity modulus of the coating material from 0.01 MPa to 100 MPa the pulsation velocity of coating surface changes not more than by 30 % and equals 0.17–0.24 of the value of dynamic flow velocity, and this can change significantly Reynolds stresses in the near-wall area. According to performed analysis, it was found out that the deformation value of the compliant coatings within the velocity range, optimal for their interaction with the turbulent flow, is only several units of the viscous scale. Moreover, these deformations are very gentle: the ratio of amplitude of deformation to wavelength is less than 10^–3. It is assumed that while modeling the interaction between the compliant coating and turbulent flow it is not necessary to transfer the boundary conditions to the moving coating surface. Perhaps, it will be sufficient to determine the velocity of wall motion over the undisturbed coating surface.

The dependence of the aerodynamic characteristics of typical multi-beam structures of bridge spans on the angle of attack, the incident flow turbulence, the number of beams, and the distance between them has been studied. For the model of three beams bridge span, the characteristic vortex structures were obtained, the thermo-anemometer probing of the near wake was performed, and the diagrams of the distribution of the averaged pressure were plotted.

The work presents the results of mathematical modeling of large-scale flows in areas with a complex topographic relief. The Reynolds-averaged Navier—Stokes equations constitute the basis of the three-dimensional unsteady modelling. The well-known Volume of Fluid method implemented in the solver interFoam of the open package OpenFOAM 1.7.1 is used to track the free-boundary location. The mathematical model adequacy is checked by comparing with experimental data. The efficiency of the applied technology is illustrated by the example of modeling the breakthrough of the dams of the Andijan (Uzbekistan) and Papan (near the Osh town, Kyrgyzstan) reservoirs.

The statements and numerical solution of the problem of igniting the wood wall as a result of the fire seat effect based on the mathematical model of a porous reacting medium are proposed. The original reagent ignition is found to be determined by the processes of drying, pyrolysis (decomposition and synthesis reactions) of dry wood, reaction of the carbon oxide oxidation as well as by the wood thermophysical properties.

Thermal conductivity of refrigerant R-415A in the vapor phase has been studied by the steady-state method of coaxial cylinders in the range of temperatures 308–415 K and pressures 0.12–1.68 MPa. The approximation dependence of thermal conductivity on pressure and temperature was determined. Thermal conductivity on the dew line and in the ideal gas state was calculated.

Tests were performed at Mach number M = 6. Observations of flow pulsations were performed with the help of high-frequency measurements of pressure and heat fluxes and with the help of hot-wire anemometry. Measurements were carried out in a broad range of Re1 numbers at various orientations and locations of sensors with respect to the nozzle exit plane. It is shown that the Transit-M noise varies weakly over the longitudinal coordinate, whereas on moving along the radial coordinate, some increase of the fluctuation level is observed due to approaching the mixing layer. Also, the distribution of axial asymmetry of the noise level was obtained.

The problem of pressure increase at a thermal effect through a non-deformable wall on a liquid filling an enclosure is considered. The solutions are obtained for the cases of the plane, radially symmetric, and spherically symmetric problem statements, which describe the pressure variation due to thermal expansion and phase transitions. The influence of the initial liquid state and the enclosure shape on the pressure variation pace are analyzed.

Both theoretically and experimentally, the suitability of a technique for studying the finely dispersed spraying of liquids based on an analysis of salt residue particles formed as a result of evaporation of test solutions of NaCl in water was evaluated. Data gained in studying the dispersion of droplets in the droplet clouds produced by pulsed and ultrasonic atomizers are reported. During pulsed atomization, salt residue particles of various morphologies were found to form, this finding pointing to realization of unsteady conditions for particle evolution.

A new method is proposed for computing the thermal conductivity of a gaseous mixture with regard for chemical reactions occurring therein, which enables the estimation of the thermal conductivity from each separate reaction to the chemical component of thermal conductivity. The method for determining the paired collision integrals, which is used in the work, is also briefly presented. The results computed by the proposed method are compared with experimental data and the data obtained by the existing computational methods in the temperature range from 500 to 2500 K under atmospheric pressure. The comparison was done both for pure gases and for the gaseous mixtures, including the combustion products of solid fuels. The obtained results may be applied for the development and design of systems related to heat exchange, gas dynamics, processing of solid and liquid fuels, for example, boiler aggregates, aviation engines, and in other applications.

A comparison of the characteristics of the boundary layer with combustion with flame stabilization by a rib and a backward-facing step is performed. The data on the thermal boundary layer, the flame blow-off velocity, and the rate of ethanol evaporation into the air flow at a turbulence of up to 26% are obtained. It is shown that the temperature of the outer region of the boundary layer and the flame blow-off velocity behind the rib is higher than behind the backward-facing step. With both methods of flame intensity, the stabilization of evaporation corresponds to the transitional regime of mass transfer.

Results of an experimental study of the operation process in a model of an air-breathing combustor operating on heated kerosene with a supersonic air flow at the combustor entrance (Mach numbers 3 and 3.5) are presented. The tests are performed in a hotshot wind tunnel in the attached pipeline configuration with total temperatures of 2350–3250 K and pressures of 3.2–12.0 MPa. Data on ignition conditions and kerosene combustion efficiency are obtained. A principal possibility of using Ozawa's criterion and its modification for the description of the range of stable combustion of the kerosene–air mixture in a combustor duct with flame holders shaped as cavities and steps in an essentially three-dimensional flow is demonstrated.

A kinetic model is developed for calculating the emission characteristics of homogeneous combustors using methane and synthesis gas (syngas) as a fuel. The model is validated over a large set of experimental data on concentrations of NO, CO, and OH in laminar flames and in the Bunsen burner and on concentrations of OH, NO, and CO in a homogeneous combustor operating on a mixture of syngas with air. At an identical temperature of combustion products, i.e., identical thermodynamic efficiency, the combustor operating on syngas is demonstrated to emit a greater amount of NO, CO, and CO₂, as compared with the combustor operating on methane. Though the use of syngas allows one to organize stable combustion of ultralean mixtures and to obtain extremely low concentrations of NO and CO at the combustor exit ( ≈ 1–3 ppm), the amount of CO₂ in the exhaust of even extremely lean mixtures (α ≈ 3) is appreciably greater than that in the case of using methane.

For the diffusion-kinetic model of combustion of a porous carbon particle in air, the structure of the reaction zone of carbon with reactive gases inside the porous particle is studied. It is shown that, for the given kinetics of reaction of carbon with oxygen, the dependence of combustion rate of the porous particle on its internal surface area is ambiguous, which is related to the strong dependence of the reaction rate of carbon with oxygen on temperature. To obtain an unambiguous dependence, it is necessary to use the kinetic equation for the reaction rate of carbon with oxygen with an activation energy lower than the experimentally determined value.

A high-pressure combustor and a metal/steam reactor are used to simulate the two-stage combustion of hydro-reactive propellants used for a water ramjet. Raw metal powders added to the propellants are the aluminum power, magnesium powder, 50/50 aluminum–magnesium alloy (AM), and ball-milled 50/50 aluminum–magnesium alloy (b-AM), which are characterized by using scanning electron microscopy (SEM), x-ray diffraction (XRD), and simultaneous thermogravimetric analysis (TGA). The efficiencies of the Al reaction in the raw metal in heated steam and in the propellants during the two-stage combustion are calculated. The results indicate that both Mg and Al in the alloys, whether b-AM or AM, can reactcompletely in air when heated up to 950 ^oC. The XRD patterns for the combustion products of the AM and b-AM alloys in heated steam contain magnesium oxide MgO, spinel Al₂MgO₄, and Al diffraction peaks. The Al reaction efficiencies of the AM and b-AM alloy powders in heated steam are much higher than that of the Al powders. The hydroxyl-terminated polybutadiene (HTPB)-ammonium perchlorate (AP)-(b-AM)-Mg and HTPB-AP-AM-Mg propellant systems exhibit good performance in terms of the Al reaction efficiency, which are better than that of the HTPB-AP-Al-Mg and HTPB-AP-Al systems.

Methods of reconstruction of the gas flow velocity from the measured velocity of disperse phase particles are considered. It is demonstrated that available approaches are limited by the low velocity nonequilibrium of the phases. A method of correction of particle image velocimetry (PIV) data on the basis of measuring the parameters of velocity relaxation of particles is proposed for measuring the gas velocity in high-gradient flows. The method is experimentally tested in the flow behind a shock wave with submicron tracers. A possibility of using this method in flows with gas-dynamic discontinuities is demonstrated.

Combustion of a palletized mixture of titanium and carbon black placed in a quartz tube and exposed to a flow of argon or nitrogen is studied. The gas flow (cocurrent filtration) is provided by a fixed pressure gradient at the inlet and outlet of the tube, which did not exceed 1 atm. The possible modes of combustion of pelletized mixtures related to the presence of a more complex hierarchy of scales (micro, macro, and meso) compared to that of powder mixtures (micro, macro) are analyzed. A comparison is made of the burning rates of powder and palletized mixtures. An increase in the burning rate when using palletized mixtures was found experimentally. It is shown that the gas coflow through the pelletized mixture of Ti + 0.5C leads to an increase in the burning rate. It is established that the propagation of the flame front of the pelletized mixture of Ti + 0.5C in flows of nitrogen and argon is controlled by different reactions. In contrast to combustion of powder mixtures of Ti + 0.5C, in combustion of pelletized mixtures of Ti + 0.5C in a nitrogen flow, only one front is observed. It is proved that radiation plays a significant role in the propagation of the combustion front in the pelletized mixture of Ti + 0.5C.

A heterogeneous model of gasless combustion of binary disperse systems is proposed. The model combines the description of microscale processes of interphase interaction in the cell of the mixture with the macroscale description, which allows physicochemical transformations to be described on the basis of the continuum approach of mechanics of continuous media and the phase composition of the final products to be calculated. Schemes of metallochemical reactions of formation and decomposition of intermetallic phases are proposed, based on an analysis of the state diagram of the Ni–Al system. A problem of SHS wave propagation and evolution of the spatial distribution of concentrations of intermetallic phases during combustion of a mixture of Ni and Al powders is solved numerically. A two-wave structure of the combustion wave is obtained, and comparisons with experimental data are performed.

A physicomathematical formulation of the coupled gas-dynamic and geometric problem of modeling intrachamber processes and calculating the internal ballistics of nozzleless solid rocket motors is given, and a method and algorithm for solving the problem are developed. The parameters in the forward section of the motor are calculated using averaged unsteady equations of internal ballistics, and the parameters of the grain channel and the exit cone are determined using one-dimensional gas-dynamic equations in a quasi-steady formulation. The software package is verified by calculating the internal ballistics of a motor which is utilized without nozzle cluster and simulates intrachamber processes in a nozzleless solid rocket motor during the full-duration firing. The design features, motor operating parameters, and the composition characteristics influencing the energetics of propellants in nozzleless solid rocket motors are calculated. It is shown that, depending on comparison conditions (identical expansion ratios and identical profiles of the nozzle and exit cone), the specific impulse of nozzleless solid rocket motors (the main energy parameter) is slightly smaller than or nearly comparable to that of conventional solid rocket motors.

In this study, characteristics of the burning rate anomaly in composite propellant grains are investigated. The burning rate anomaly has been known as the “midweb anomaly” or the “hump effect.” This paper describes some results of an experimental study on effects of propellant formulations, casting processes, and viscosity of the propellant slurry on the phenomena. According to some past studies, it has been suggested that the geometry of the “isochrone surface” of the propellant slurry affects the local burning rate. To investigate the effect of the isochrone surface, visualization of the isochrone surface in composite propellant grains is carried out. A relation between the geometry and the local burning rate measured in motor firing tests and strand tests is proposed. As a result, besides the common static characteristics of the burning rate anomaly, i.e., the pressure hump effect and the nonisotropic characteristic of the local burning rate, a peculiar burning rate distribution in connection with the isochrone surface is obtained.

Nonlinear response functions of the burning rate to pressure oscillations are calculated for RDX and HMX in a quadratic approximation. Values of the burning surface temperature of HMX and RDX and the sensitivities of the burning rate and surface temperature to the initial temperature and pressure are given. A statistical analysis of the measurement and calculation errors is performed. The characteristics of the nonlinear response functions are considered. Some issues of the physics of combustion of nitramines are briefly discussed.

Pyrolysis of wood in vibro-fluidized beds of disperse packings of deep oxidation catalysts and inert materials is investigated. It is shown that the properties of the disperse packing material of vibro-fluidized beds do not have a significant effect on the rate and degree of conversion of wood to volatiles. The presence of catalysts in the vibro-fluidized bed leads to an increase in the amount of CO₂, CO, H₂, and CH₄ in the gas phase compared to the pyrolysis of wood in vibro-fluidized beds of inert materials. The greatest activity in the conversion of volatiles to CO₂, CO, H₂, CH₄ was found for the catalyst IK-12-73 (Mg_0.5Cu_0.5Cr₂O₄/Al₂O₃). The accumulation of carbon in IK-12-73 catalyst has little effect on the conversion of volatile substances to gaseous products. The degree of burnout of wood particles under conditions of a vibro-fluidized bed of IK-12-73 catalyst is 99.7%, which is consistent with data on the catalytic combustion of wood in the fluidized bed.

Preliminarily results on the reaction mechanism of detonation of composite emulsion explosives sensitized by MgH₂, which simultaneously plays the role of an energetic material, are presented. Compared to emulsion explosives sensitized by glass microspheres, emulsion explosives sensitized by magnesium hydride have a different reaction mechanism of detonation. The shock wave overpressure, specific impulse, shock wave energy, and bubble energy are all greatly increased with the use of MgH₂, and it is noticeable that the shock wave overpressure and shock wave energy increase by 17% and 24%, respectively. In addition, emulsion explosives sensitized by MgH₂ improve significantly in terms of detonation velocity and brisance. These emulsion explosives also meet safety requirements.

This paper presents the results of a study of the formation of localized shear in M1 copper of two types: as-received and after preloading by a quasi-entropic compression wave. The experiments were performed with hat-shaped samples using the split Hopkinson bar method. For both types of copper, dynamic compression diagrams were obtained at strain rates of 2100–2500 s^–1. The copper structure was subjected to metallographic analysis, and the effect of preliminary shock deformation on the dynamic mechanical properties of the material was estimated. It is shown that preloaded higher-strength metals with a smaller degree of strain hardening are more prone to the formation of adiabatic shear bands.