Showing papers in "Journal of Engineering Physics in 2009"
TL;DR: The density, the isobaric expansion coefficient, the specific heat at constant pressure and constant volume, and the isothermal compressibility coefficient of liquid n-hexadecane have been calculated in the range of temperatures 298-433 K and pressures 0.1-140 MPa from the data on the velocity of sound as mentioned in this paper.
Abstract: The density, the isobaric expansion coefficient, the specific heats at constant pressure and constant volume, and the isothermal compressibility coefficient of liquid n-hexadecane have been calculated in the range of temperatures 298–433 K and pressures 0.1–140 MPa from the data on the velocity of sound. The coefficients of the Tate equation in the above parametric range have been determined. The table of the thermodynamic properties of n-hexadecane has been presented.
24 citations
TL;DR: The experimental data published by various authors who studied the burnout heat transfer in boiling have been analyzed. as discussed by the authors showed that the critical heat flux depends substantially on the physical properties of both the boiling liquid and cooled wall and its geometric parameters.
Abstract: The experimental data published by various authors who studied the burnout heat transfer in boiling have been analyzed. It is shown that the critical heat flux depends substantially on the physical properties of both the boiling liquid and cooled wall and its geometric parameters.
20 citations
TL;DR: In this article, an experimental facility and methods for measuring the aerodynamic and thermal parameters in the interaction between a pulse spray and a vertical surface were described, where the spray-forming unit contains 16 atomizers with opening time regulation (from 1 to 10 msec) and a frequency of up to 50 Hz.
Abstract: This paper describes an experimental facility and methods for measuring the aerodynamic and thermal parameters in the interaction between a pulse spray and a vertical surface The spray-forming unit contains 16 atomizers with opening time regulation (from 1 to 10 msec) and a frequency of up to 50 Hz The experiments were performed in the regime of evaporation of the liquid precipitated on the surface in the form of separate drops, rivulets, and a continuously flowing sheet It has been shown that depending on the time parameters of the pulse spray, the integral heat transfer can effectively be controlled over a wide range
17 citations
TL;DR: In this article, the results of numerical simulation of fully developed turbulent flow in a channel with the cube on the lower wall (for the characteristic Reynolds number Re = 40,000) within the traditional approach to the solution of unsteady Reynolds-averaged Navier-Stokes equations (URANS) in combination with the semiempirical Spalart-Allmaras turbulence model (with a correction for rotation) have been presented.
Abstract: The results of numerical simulation of fully developed turbulent flow in a channel with the cube on the lower wall (for the characteristic Reynolds number Re = 40,000) within the framework of the traditional approach to the solution of unsteady Reynolds-averaged Navier–Stokes equations (URANS) in combination with the semiempirical Spalart–Allmaras turbulence model (with a correction for rotation) have been presented. A detailed comparative analysis of the results of numerical simulation of local and integral flow characteristics and the Martinuzzi experimental data has shown that the self-oscillating regime of flow past the cube is a superposition of oscillations of the arms of a horseshoe vortex and the rear arched and detached vortex structures. Using fast Fourier transformation, it has been found that the oscillations are of a bimodal character in the longitudinal and vertical directions, whereas in the transverse direction, they are of a unimodal character.
15 citations
TL;DR: In this paper, the integral heat balance method based on the introduction of the temperature perturbation field and additional boundary conditions is used to find analytical solutions of boundary-value problems of nonstationary heat conduction that permits obtaining, for a series of problems, solutions with a given degree of accuracy throughout the range of variation of the Fourier number.
Abstract: With the use of the integral heat balance method based on the introduction of the temperature perturbation field and additional boundary conditions, we consider a method for finding analytical solutions of boundary-value problems of nonstationary heat conduction that permits obtaining, for a series of problems, solutions with a given degree of accuracy throughout the range of variation of the Fourier number. Solutions have a simple form of exponential algebraic polynomials, which makes it possible to investigate the heat transfer in the fields of isothermal lines, as well as analyze the time distributions of velocities of motion of isotherms.
15 citations
TL;DR: A review of peat fires under laboratory and natural conditions can be found in this article, where it is shown that the smoldering of surface combustible materials in peatlands involves half the biomass burnt during natural (forest, steppe, and peat) fires.
Abstract: Works devoted to experimental and theoretical investigations of peat fires under laboratory and natural conditions have been reviewed. Evaluations show that the smoldering of surface combustible materials in peatlands involves half the biomass burnt during natural (forest, steppe, and peat) fires. These fires are of first importance in emission of combustion products into the atmosphere, destruction of the soil structure, and damage to the environment. Many investigations have been carried out on the problem of peat-fire behavior, and they have been published in various journals and materials of conferences.
15 citations
TL;DR: In this article, the bactericidal action of the plasma of a high-frequency discharge excited at a frequency f = 5.28 MHz and a low pressure in air on different test-strains of microorganisms has been investigated.
Abstract: The bactericidal action of the plasma of a high-frequency discharge excited at a frequency f = 5.28 MHz and a low pressure in air on different test-strains of microorganisms has been investigated. The high-efficiency plasma inactivation of strains of E. coli, B. subtilis, C. albicans, and S. aureus at an initial contamination N
0 ≤ 103 CFU / ml was detected. It was established that the most probable sterilization agents of the plasma generated are the “hot” and “cold” OH radicals, the excited electrically neutral N2 and O2 molecules, and the UV plasma radiation.
13 citations
TL;DR: In this article, the mass transfer in the process of drying of deformable porous bodies was theoretically investigated and the corresponding mass-transfer equation was analytically solved on the basis of experimental data on the drying of porous materials.
Abstract: The mass transfer in the process of drying of deformable porous bodies was theoretically investigated and the corresponding mass-transfer equation was analytically solved. On the basis of experimental data on the drying of porous materials, the ill-posed inverse problem on determination of the region of regular change in the effective diffusion coefficient and in the porosity of a porous-material layer with time was solved.
13 citations
TL;DR: In this article, the authors investigated the free vibrations in a microstretch thermoelastic homogeneous isotropic plate subjected to stress-free thermally insulated and isothermal conditions.
Abstract: The propagation of free vibrations in a microstretch thermoelastic homogeneous isotropic plate subjected to stress-free thermally insulated and isothermal conditions is investigated in the context of conventional coupled thermoelasticity (CT) and Green and Lindsay (G—L) theories of thermoelasticity. The secular equations for the microstretch thermoelastic plate in closed form for symmetric and skew-symmetric wave mode propagation in completely separate terms are derived. At short wavelength limits, the secular equations for both modes in a stress-free thermally insulated and isothermal homogeneous isotropic microstretch thermoelastic plate reduce to the Rayleigh surface wave frequency equation. The results for symmetric and skew-symmetric wave modes are computed numerically and presented graphically. The theory and numerical computations are found to be in close agreement.
13 citations
TL;DR: In this paper, it has been shown that the method of digital dynamic speckle photography is an efficient method of quantitative and qualitative diagnostics in orthopedic stomatology for optimization of the constructions of cermet dentures by evaluating their stressed-strained state.
Abstract: It has been shown that the method of digital dynamic speckle photography is an efficient method of quantitative and qualitative diagnostics in orthopedic stomatology for optimization of the constructions of cermet dentures by evaluating their stressed-strained state. Determination of the stressed-strained state of cermet dentures by the method of digital laser speckle photography at the stages of their manufacture makes it possible to most reliably investigate the quality of manufactured constructions, which diminishes the number of complications and improves the efficiency of treatment in orthopedic stomatology,
12 citations
TL;DR: In this article, a supersonic counterflow jet from the stagnation point of a 60-deg apex angle blunt cone is conducted in a free piston driven hypersonic shock tunnel, HST3, to verify the effectiveness of this technique for high enthalpy flows.
Abstract: Heat transfer reduction studies, in the presence of a supersonic counterflow jet from the stagnation point of a 60-deg apex angle blunt cone, are conducted in a free piston driven hypersonic shock tunnel, HST3, to verify the effectiveness of this technique for high enthalpy flows. For flow of Mach number 8 with stagnation enthalpy of 5 MJ/kg, it has been observed that the heat transfer rate at some location decreases initially with increase in the injection pressure ratio until the critical injection pressure ratio is reached. A forty-five percent reduction in heat transfer rate near the stagnation point has been measured for the critical injection pressure ratio, equal to 14.91. A further increase in the injection pressure ratio reduces the overall percentage heat transfer reduction. The dependence of fluidic spike length on percentage heat transfer reduction has been confirmed.
TL;DR: In this paper, the authors studied the propagation of Rayleigh waves in a homogeneous, transversely isotropic, thermoelastic diffusive half-space that is subjected to stress-free, thermally insulated/isothermal, and chemical potential boundary conditions in the context of the generalized theory of diffusion.
Abstract: This paper is devoted to the study of propagation of Rayleigh waves in a homogeneous, transversely isotropic, thermoelastic diffusive half-space that is subjected to stress-free, thermally insulated/isothermal, and chemical potential boundary conditions in the context of the generalized theory of thermoelastic diffusion. The Lord and Shulman theory, where thermal and thermomechanical relaxation as well as diffusion relaxation are governed by two different time constants, is selected. Secular equations for surface wave propagation in the considered media are derived. The amplitudes of surface displacements, temperature change, and concentration are computed. The paths of the surface particles are determined. Transverse isotropy and diffusion effects on the phase velocity, group velocity, and attenuation coefficient are presented graphically.
TL;DR: In this article, the influence of the time of treatment of the tap and distilled water used for tempering of fine concretes by a high-frequency magnetic field on the technological characteristics of these concrete was investigated.
Abstract: The influence of the time of treatment of the tap and distilled water used for tempering of plasticized fine concretes by a high-frequency magnetic field on the technological characteristics of these concretes was investigated. The optimum regimes of treatment of the mixing water by this field and the dependence of the properties of the concretes obtained with it on the time of its storage after the treatment were determined.
TL;DR: In this paper, the formation of carbon nanostructures in a reactor as a result of the decomposition of hydrocarbons in a low-temperature plasma was investigated. But the results were limited to the case of a metal containing iron and nickel.
Abstract: Results of experimental investigations on the formation of carbon nanostructures in a reactor as a result of the decomposition of hydrocarbons in a low-temperature plasma are presented. The influence of the internal geometry of the reactor, the temperature regimes, and the relative content of a reagent and an oxidizer in the working mixture on the formation of carbon nanostructures has been investigated. It was established that ordered carbon structures are formed on the surface of a metal containing iron and nickel. Data on the production rate of the process and the content of the structured carbon in the material obtained are presented.
TL;DR: In this article, the influence of the Reynolds number on the patterns of separation laminar and turbulent flows around a plane plate with a shallow hole was analyzed on the basis of the solution of the differential mass- and energy-conservation equations, the Navier-Stokes equations, and the Reynolds equations closed with the use of the shear-stress transfer model by the factorized finite-volume method.
Abstract: The influence of the Reynolds number on the patterns of separation laminar and turbulent flows around a plane plate with a shallow hole as well as on the thermal-hydraulic characteristics of this plate was analyzed on the basis of the solution of the differential mass- and energy-conservation equations, the Navier–Stokes equations, and the Reynolds equations closed with the use of the shear-stress transfer model by the factorized finite-volume method.
TL;DR: In this paper, a numerical simulation of fiery whirlwinds originating as a result of blowing-in of a twisted flow of a fuel gas into an initially stagnant medium is carried out, and the results of calculations agree with experimental values in the entire range of twistings studied.
Abstract: Numerical simulation of fiery whirlwinds originating as a result of blowing-in of a twisted flow of a fuel gas into an initially stagnant medium is carried out. The results of calculations agree with experimental values in the entire range of twistings studied.
TL;DR: In this article, an analysis is made of equations of the one-velocity model of a heterogeneous mixture; in them, the internal interfractional-interaction forces and heat-and mass exchange processes are allowed for.
Abstract: An analysis is made of equations of the one-velocity model of a heterogeneous mixture; in them, the internal interfractional-interaction forces and heat- and mass-exchange processes are allowed for. The characteristic equations and relations along the characteristic directions are found. It is shown that equations of the medium’s model, in which the interfractional-interaction forces are allowed for, belong to a hyperbolic type. A number of finite-difference and finite-volume schemes meant for integration of the model’s equations are considered.
TL;DR: In this article, a two-dimensional oscillatory free convective flow of an incompressible polar fluid through a porous medium bounded by an infinite vertical porous plate with oscillating suction and temperature at the wall is analyzed.
Abstract: The aim of this work is to analyze a two-dimensional oscillatory free convective flow of an incompressible polar fluid through a porous medium bounded by an infinite vertical porous plate with oscillating suction and temperature at the wall. The governing equations are based on the volume averaging technique. Analytical expressions for the velocity, angular velocity, and temperature fields are obtained by using the regular perturbation technique. The analysis reveals a multiple boundary layer structure near the wall for the fields mentioned.
TL;DR: In this article, an unsteady supersonic flow of a nonviscous gas with a Mach number M = 3 in a step-shaped channel has been calculated on the basis of the Roe dissipation model and the advective upwind splitting method with the use of convective schemes of the second and third orders of accuracy.
Abstract: An unsteady supersonic flow of a nonviscous gas with a Mach number M = 3 in a step-shaped channel has been calculated. The accuracy of the forecasts made has been analyzed on the basis of the Roe dissipation model and the advective upwind splitting method with the use of convective schemes of the second and third orders of accuracy and algorithms for approximation of flows. Triangular and polyhedral grids have been tested. The mechanism of formation of an artificial physical instability on grid structures with a local-gradient adaptation has been considered. It is shown that the existence of a singular point — a right corner — in the computational region causes a large phase change in the evolution of the flow.
TL;DR: In this paper, the processes of moisture desorption by a sorbent-drier of the type of "salt in a porous matrix" and sawdust in convective flow, as well as under the acoustoconvective action, have been investigated.
Abstract: The processes of moisture desorption by a sorbent-drier of the type of “salt in a porous matrix” and sawdust in convective flow, as well as under the acoustoconvective action, have been investigated. It has been shown that at a flow velocity of 31 m ⁄ sec the sorbent has a rather prolonged drying stage with a constant rate, and at a flow velocity of 13 m ⁄ sec this drying stage ends faster. It has been established that the velocity of the convective flow strongly influences the drying process of the sorbent, and the action of the acoustic field therewith produced no marked effect on the drying process. Moisture desorption from sawdust proceeds with a variable rate, and its intensity markedly increases under the action of the acoustic field. The influence of acoustic vibrations on the rate of moisture removal has a nonmonotonic character. The kinetics of the process of humidification of the sorbent-drier has been investigated. On the basis of the investigations made, a basic circuit for ventilating closed rooms by dried air with the use of sawdust or an IK-011-1 sorbent-drier has been proposed.
TL;DR: In this paper, the process of ignition of a mixture of air and a kerosene vapor by a steel wire heated to high temperatures has been modeled numerically and investigated on a model allowing for the combination of heat and mass-transfer processes.
Abstract: The process of ignition of a mixture of air and a kerosene vapor by a steel wire heated to high temperatures has been modeled numerically. The investigations have been carried out on a model allowing for the combination of heat- and mass-transfer processes (evaporation of the flammable liquid, diffusion and convection of the fuel vapor in air, heat conduction, and oxidation of the fuel vapor in air). The values of the delay time of ignition of the vapor-gas mixture have been determined and the scale of influence of the initial temperature and dimensions of the wire, the distance between the heating source and the kerosene surface, and the temperature and humidity of air on the inertia of the ignition process have been established.
TL;DR: In this article, the results of an experimental study of the thermomechanical drying of cylinder-shaped wood by the depressurization method are presented, and the high rate of the process of thermodynamic drying with a good quality of dried articles has been confirmed.
Abstract: The results of an experimental study of the thermomechanical drying of cylinder-shaped wood by the depressurization method are presented. The high rate of the process of thermomechanical drying with a good quality of dried articles has been confirmed.
TL;DR: In this paper, a model of fast pyrolysis of a wood particle including the heating of the particle in a boiling bed under regular conditions, the pyrolys kinetics of the three basic components of the biomass (cellulose, hemicellulose and lignin), and the destruction kinetics, as well as a submodel of particle motion in the free space of the reactor.
Abstract: We have developed a model of fast pyrolysis of a biomass (wood) particle including the heating of the particle in a boiling bed under regular conditions, the pyrolysis kinetics of the three basic components of the biomass (cellulose, hemicellulose, and lignin), and the destruction kinetics of the intermediate pyrolysis products, as well as a submodel of the particle motion in the free space of the reactor. The numerical optimization of the fast pyrolysis performed by us has shown that the main control parameter of the process determining the yield of liquid biofuel is the temperature of the boiling bed.
TL;DR: In this paper, the authors present the process of steam thermolysis of shredded used tires for obtaining from them liquid fuel and technical carbon carried out in a screw reactor with heating due to the partial burning of obtained fuel and burning of the tail combustible gas.
Abstract: This paper presents the process of steam thermolysis of shredded used tires for obtaining from them liquid fuel and technical carbon carried out in a screw reactor with heating due to the partial burning of obtained fuel and burning of the tail combustible gas. The features and advantages of using steam for safety and stability of the process, including the problem of secondary waste slime processing, have been considered. The specific fuel consumption and the steam generation per 1 kg of processed tires and, separately, the gas consumption for power supply (heating) of the process without using fuel, as well as with additional burning of fuel for processing slime together with tires, have been considered.
TL;DR: In this paper, a tuning fork-based atomic force microscopy (AFM) was used to investigate the tip-sample interactions at the nanoscale in the shear-force mode.
Abstract: A quartz tuning fork-based atomic force microscopy for investigating the tip–sample interactions at the nanoscale in the shear-force mode is described. Results of force interactions (damping and elastic forces) can be obtained from the amplitude-phase-distance spectroscopy measurements made with a tuning fork with a tungsten tip and a sample surface. The influence of the interaction between tip and sample using the quality factor as an indicator is investigated. Furthermore, a simple model shows that the extension of a tuning fork-based AFM can be applied to quantitative analysis of the properties of the sample surface.
TL;DR: In this paper, the results of experimental investigations of the hydrodynamic resistance in spherical fills as applied to the cores of nuclear reactors with spherical fuel elements are presented, and the experimental setup and the procedures of preparation of models, measurement, and processing of experimental data are described.
Abstract: The results of experimental investigations of the hydrodynamic resistance in spherical fills as applied to the cores of nuclear reactors with spherical fuel elements are presented. The experimental setup and the procedures of preparation of models, measurement, and processing of experimental data are described. The criterial dependences satisfactorily describing data on resistance in motion of single- and two-phase media in spherical fills are obtained.
TL;DR: In this paper, a numerical investigation of the nonisothermal effects occurring in the process of growth of carbon clusters in the gas phase in the temperature range 2000-3000 K has been carried out and it has been established that these effects are due to the phase transition latent heat released as a result of the volume condensation of nonequilibrium carbon vapor as well as the convective and radiative cooling of the clusters.
Abstract: A numerical investigation of the nonisothermal effects occurring in the process of growth of carbon clusters in the gas phase in the temperature range 2000–3000 K has been carried out. It has been established that these effects are due to the phase-transition latent heat released as a result of the volume condensation of nonequilibrium carbon vapor as well as the convective and radiative cooling of the clusters. It is shown that, under the indicated conditions, the radiative cooling of carbon clusters is the dominant cooling mechanism. A mathematical simulation was carried out for the cases of optically thin and thick layers of a vapor-gas mixture embedded in cold walls. The dependence of the growth and temperature of the carbon clusters on their porosity, the supersaturation of the carbon vapor, and the temperature of the vapor-gas mixture was detected. It has been established that the temperature of the growing carbon clusters can be higher or lower than the temperature of the vapor-gas mixture and the deviation from this temperature can exceed 500 K. The data obtained were compared with the results of experiments on shock tubes.
TL;DR: In this paper, a method of monitoring the homogeneity and determination of the workability index of a concrete mix from the level of vibroacoustic vibrations excited in the mixer in mixing of concrete has been described.
Abstract: The method of monitoring of the homogeneity and determination of the workability index of a concrete mix from the level of vibroacoustic vibrations excited in the mixer in mixing of concrete has been described. The vibration-level values dependent on the hydromechanical state of a concrete mix and its rheological characteristics in the process of mixing and formation of its vibroacoustic image have been measured at the check point of the lining of the concrete mixer and have mathematically been processed.
TL;DR: Based on the principle of hydrodynamic equivalence, a technique to calculate the velocity of complete fluidization of polydisperse granular materials of different densities with allowance for the transformation of their initial size distribution has been worked out as discussed by the authors.
Abstract: Based on the principle of hydrodynamic equivalence, a technique to calculate the velocity of complete fluidization of polydisperse granular materials of different densities with allowance for the transformation of their initial size distribution has been worked out.
TL;DR: A mathematical model has been developed and an algorithm of calculation of heat and mass-transfer processes in heating and melting of metal scrap in an electric-arc steel-making furnace has been created.
Abstract: A mathematical model has been developed and an algorithm of calculation of heat- and mass-transfer processes in heating and melting of metal scrap in an electric-arc steel-making furnace has been created. The results of numerical modeling of the dynamics of melting of metal scrap in this furnace have been given.