Pub Date : 2024-03-21DOI: 10.1134/s0018151x23050048
I. A. Ermolaev
Abstract
The results of a numerical study of the local and average heat transfer during the natural thermal convection of air in a square-shaped area with two symmetrical horizontal partitions (fins) in the middle of the sides are presented. The region is heated from below by a constant uniform heat flow, the horizontal boundaries and partitions are assumed to be adiabatic, and the upper boundary is assumed to be isothermal. The dependences of the local and average Nusselt numbers on the size of the partitions and the intensity of the convective flow are obtained.
{"title":"Natural Thermogravitational Convection in a Partially Blocked Square Area Heated from Below: Local and Medium Heat Transfer","authors":"I. A. Ermolaev","doi":"10.1134/s0018151x23050048","DOIUrl":"https://doi.org/10.1134/s0018151x23050048","url":null,"abstract":"<h3 data-test=\"abstract-sub-heading\">Abstract</h3><p>The results of a numerical study of the local and average heat transfer during the natural thermal convection of air in a square-shaped area with two symmetrical horizontal partitions (fins) in the middle of the sides are presented. The region is heated from below by a constant uniform heat flow, the horizontal boundaries and partitions are assumed to be adiabatic, and the upper boundary is assumed to be isothermal. The dependences of the local and average Nusselt numbers on the size of the partitions and the intensity of the convective flow are obtained.</p>","PeriodicalId":13163,"journal":{"name":"High Temperature","volume":"66 1","pages":""},"PeriodicalIF":1.0,"publicationDate":"2024-03-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140887178","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-03-21DOI: 10.1134/s0018151x23040107
V. V. Mironov, M. A. Tolkach, V. V. Tlevtsezhev
Abstract
A method to analyze the influence of chemical reactions on heat-and-mass transfer in a reactive boundary layer has been suggested, and the influence of thermal effects on the overall heat-and-mass transfer coefficient has been estimated. It has been found that endothermal reactions in the boundary layer have a considerable effect on the overall heat-and-mass transfer coefficient. Taking into account the influence of thermal effects due to homogeneous reactions inside the boundary layer on convective thermal flux ({{dot {q}}_{lambda }}) is equivalent to taking into account the heat of these reactions on the surface of a heat protection coating, that is, on the surface of a coked layer.
{"title":"Influence of Chemical Reactions in a Boundary Layer on the Overall Heat-and-Mass Transfer Coefficient","authors":"V. V. Mironov, M. A. Tolkach, V. V. Tlevtsezhev","doi":"10.1134/s0018151x23040107","DOIUrl":"https://doi.org/10.1134/s0018151x23040107","url":null,"abstract":"<h3 data-test=\"abstract-sub-heading\">Abstract</h3><p>A method to analyze the influence of chemical reactions on heat-and-mass transfer in a reactive boundary layer has been suggested, and the influence of thermal effects on the overall heat-and-mass transfer coefficient has been estimated. It has been found that endothermal reactions in the boundary layer have a considerable effect on the overall heat-and-mass transfer coefficient. Taking into account the influence of thermal effects due to homogeneous reactions inside the boundary layer on convective thermal flux <span>({{dot {q}}_{lambda }})</span> is equivalent to taking into account the heat of these reactions on the surface of a heat protection coating, that is, on the surface of a coked layer.</p>","PeriodicalId":13163,"journal":{"name":"High Temperature","volume":"51 1","pages":""},"PeriodicalIF":1.0,"publicationDate":"2024-03-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140203247","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-03-21DOI: 10.1134/s0018151x23050115
Yu. A. Nikitchenko, S. A. Popov, N. I. Sergeeva
Abstract
A mathematical model of a multicomponent gas flow based on a model kinetic equation is presented. Flows of multicomponent monatomic perfect gases are considered. The model is tested using the example of the problem of the shock wave profile for a mixture of argon and helium in various proportions. It is shown that the model provides satisfactory agreement with the experimental data.
{"title":"System of Model Kinetic Equations for a Multicomponent Gas","authors":"Yu. A. Nikitchenko, S. A. Popov, N. I. Sergeeva","doi":"10.1134/s0018151x23050115","DOIUrl":"https://doi.org/10.1134/s0018151x23050115","url":null,"abstract":"<h3 data-test=\"abstract-sub-heading\">Abstract</h3><p>A mathematical model of a multicomponent gas flow based on a model kinetic equation is presented. Flows of multicomponent monatomic perfect gases are considered. The model is tested using the example of the problem of the shock wave profile for a mixture of argon and helium in various proportions. It is shown that the model provides satisfactory agreement with the experimental data.</p>","PeriodicalId":13163,"journal":{"name":"High Temperature","volume":"9 1","pages":""},"PeriodicalIF":1.0,"publicationDate":"2024-03-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140203372","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-03-21DOI: 10.1134/s0018151x23050176
A. S. Shumikhin
Abstract
A simple physical model of atomic plasma is proposed, which makes it possible to calculate the equation of state of refractory metals in the near-critical region and obtain the parameters of the critical point of the vapor–liquid phase transition, including the binodal. A special feature of the model is that it takes into account interatomic interaction using cohesion—the collective energy of the cohesion of atoms in a metal. Estimates of the critical point parameters for many refractory metals, including the conductivity at the critical point, are obtained.
{"title":"The Problem of the Equation of State of Refractory Metals in the Near-Critical Region","authors":"A. S. Shumikhin","doi":"10.1134/s0018151x23050176","DOIUrl":"https://doi.org/10.1134/s0018151x23050176","url":null,"abstract":"<h3 data-test=\"abstract-sub-heading\">Abstract</h3><p>A simple physical model of atomic plasma is proposed, which makes it possible to calculate the equation of state of refractory metals in the near-critical region and obtain the parameters of the critical point of the vapor–liquid phase transition, including the binodal. A special feature of the model is that it takes into account interatomic interaction using cohesion—the collective energy of the cohesion of atoms in a metal. Estimates of the critical point parameters for many refractory metals, including the conductivity at the critical point, are obtained.</p>","PeriodicalId":13163,"journal":{"name":"High Temperature","volume":"162 1","pages":""},"PeriodicalIF":1.0,"publicationDate":"2024-03-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140203356","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-03-21DOI: 10.1134/s0018151x23050127
S. V. Onufriev, A. I. Savvatimskiy
Abstract
Experiments are carried out on rapid heating by an electric current pulse of plates for anisotropic graphite and gadolinium foil clamped in the same way: between two thick-walled plates of TF-5 glass (heavy flint). In both cases, the glass cells were previously compressed with a clamp to create some initial pressure. During the passage of the current pulse (5 μs), the pressure in the samples is estimated; it increases due to thermal expansion when confined by the glass plates. The electrical resistance of liquid carbon at low pressures (up to 1 kbar) increases with increasing temperature, just as for most conductors. Under limited expansion (increasing pressure), the electrical resistance of liquid carbon becomes constant, independent of the increase in temperature and pressure (up to 9000 K). Unlike carbon, the electrical resistance of liquid gadolinium at elevated pressure (about 1 kbar) practically did not change (~260 µm cm) and remained approximately constant, as at lower pressures (~0.3 kbar); and at high temperatures, up to 6000 K.
{"title":"Electrical Resistance of Liquid Carbon (up to 9000 K) and Liquid Gadolinium (up to 6000 K) at Elevated Pressure and High Temperatures","authors":"S. V. Onufriev, A. I. Savvatimskiy","doi":"10.1134/s0018151x23050127","DOIUrl":"https://doi.org/10.1134/s0018151x23050127","url":null,"abstract":"<h3 data-test=\"abstract-sub-heading\">Abstract</h3><p>Experiments are carried out on rapid heating by an electric current pulse of plates for anisotropic graphite and gadolinium foil clamped in the same way: between two thick-walled plates of TF-5 glass (heavy flint). In both cases, the glass cells were previously compressed with a clamp to create some initial pressure. During the passage of the current pulse (5 μs), the pressure in the samples is estimated; it increases due to thermal expansion when confined by the glass plates. The electrical resistance of liquid carbon at low pressures (up to 1 kbar) increases with increasing temperature, just as for most conductors. Under limited expansion (increasing pressure), the electrical resistance of liquid carbon becomes constant, independent of the increase in temperature and pressure (up to 9000 K). Unlike carbon, the electrical resistance of liquid gadolinium at elevated pressure (about 1 kbar) practically did not change (~260 µm cm) and remained approximately constant, as at lower pressures (~0.3 kbar); and at high temperatures, up to 6000 K.</p>","PeriodicalId":13163,"journal":{"name":"High Temperature","volume":"33 1","pages":""},"PeriodicalIF":1.0,"publicationDate":"2024-03-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140887450","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-03-21DOI: 10.1134/s0018151x23050073
K. V. Khishchenko
Abstract
This paper describes the thermodynamic properties of zirconium in a high-pressure region. The available experimental data on isothermal and shock compression of this metal are summarized in the form of a simple model that specifies a pressure function of the specific volume and specific internal energy. The results of calculations of the thermodynamic characteristics of the body-centered cubic crystalline phase and zirconium melt are presented in comparison with the available experimental data in the studied range of thermodynamic parameters. The resulting equation of state can be used in the numerical modeling of adiabatic processes at high energy concentrations.
{"title":"Equation of State of Zirconium at High Pressures","authors":"K. V. Khishchenko","doi":"10.1134/s0018151x23050073","DOIUrl":"https://doi.org/10.1134/s0018151x23050073","url":null,"abstract":"<h3 data-test=\"abstract-sub-heading\">Abstract</h3><p>This paper describes the thermodynamic properties of zirconium in a high-pressure region. The available experimental data on isothermal and shock compression of this metal are summarized in the form of a simple model that specifies a pressure function of the specific volume and specific internal energy. The results of calculations of the thermodynamic characteristics of the body-centered cubic crystalline phase and zirconium melt are presented in comparison with the available experimental data in the studied range of thermodynamic parameters. The resulting equation of state can be used in the numerical modeling of adiabatic processes at high energy concentrations.</p>","PeriodicalId":13163,"journal":{"name":"High Temperature","volume":"8 1","pages":""},"PeriodicalIF":1.0,"publicationDate":"2024-03-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140203249","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-03-21DOI: 10.1134/s0018151x2305005x
I. N. Ganiev, R. S. Shonazarov, A. Elmurod, U. N. Faizulloev
Abstract
The results of the experimental determination of the heat capacity of the aluminum alloy AlCu4.5Mg1 alloyed with barium and the calculation of the temperature dependences of changes in the thermodynamic functions of this alloy are presented. Studies of the temperature dependence of the heat capacity of the AlCu4.5Mg1 alloy alloyed with barium are carried out in the cooling mode using a computer and the Sigma Plot 10.0 software. The types of polynomials of the temperature dependence of the heat capacity and changes in thermodynamic functions (enthalpy, entropy, and Gibbs energy) of the studied alloy and the standard (Al grade A5N), which describe these changes with the correlation coefficient Rcor = 0.999, are established. It is shown that with the increasing barium content, the heat capacity of the original alloy decreases. The enthalpy and entropy of the AlCu4.5Mg1 alloy alloyed with barium increase with increasing temperature, and decrease with the increasing barium content. The Gibbs energy values have an inverse relationship.
{"title":"Heat Capacity and Thermodynamic Functions of the Aluminum Alloy AlCu4.5Mg1 Alloyed with Barium","authors":"I. N. Ganiev, R. S. Shonazarov, A. Elmurod, U. N. Faizulloev","doi":"10.1134/s0018151x2305005x","DOIUrl":"https://doi.org/10.1134/s0018151x2305005x","url":null,"abstract":"<h3 data-test=\"abstract-sub-heading\">Abstract</h3><p>The results of the experimental determination of the heat capacity of the aluminum alloy AlCu4.5Mg1 alloyed with barium and the calculation of the temperature dependences of changes in the thermodynamic functions of this alloy are presented. Studies of the temperature dependence of the heat capacity of the AlCu4.5Mg1 alloy alloyed with barium are carried out in the cooling mode using a computer and the Sigma Plot 10.0 software. The types of polynomials of the temperature dependence of the heat capacity and changes in thermodynamic functions (enthalpy, entropy, and Gibbs energy) of the studied alloy and the standard (Al grade A5N), which describe these changes with the correlation coefficient <i>R</i><sub>cor</sub> = 0.999, are established. It is shown that with the increasing barium content, the heat capacity of the original alloy decreases. The enthalpy and entropy of the AlCu4.5Mg1 alloy alloyed with barium increase with increasing temperature, and decrease with the increasing barium content. The Gibbs energy values have an inverse relationship.</p>","PeriodicalId":13163,"journal":{"name":"High Temperature","volume":"11 1","pages":""},"PeriodicalIF":1.0,"publicationDate":"2024-03-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140203355","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-03-21DOI: 10.1134/s0018151x23050061
E. M. Kartashov
Abstract
Mathematical model representations of the temperature effect in regions with a thermally insulated moving boundary are developed. The boundary conditions for thermal insulation of a moving boundary are formulated both for locally equilibrium heat transfer processes within the classical Fourier phenomenology and for more complex locally nonequilibrium processes within the Maxwell–Cattaneo–Lykov–Vernott phenomenology, taking into account the finite speed of heat propagation. The applied problem of heat conductance and the theory of thermal shock for a region with a moving thermally insulated boundary, free from external and internal influences, is considered. An exact analytical solution of the formulated mathematical models for equations of the hyperbolic type is obtained. Methods and theorems of operational calculus and Riemann–Mellin contour integrals are used to calculate the originals of complex images with two branch points. A mathematical apparatus for the equivalence of functional structures for the originals of the obtained operational solutions is proposed. It is shown that the presence of a thermally insulated moving boundary leads to the appearance of a temperature gradient in the region and, consequently, to the appearance in the region of a temperature field and corresponding thermoelastic stresses of a wave nature. A numerical experiment is presented and the possibility of transition from one form of analytical solution of the temperature problem to another equivalent form is shown. The described effect manifests itself both for equations of the parabolic type based on classical Fourier phenomenology and for equations of hyperbolic type based on the generalized phenomenology of Maxwell–Cattaneo–Lykov–Vernott.
{"title":"Thermal State of a Region with a Thermally Insulated Moving Boundary","authors":"E. M. Kartashov","doi":"10.1134/s0018151x23050061","DOIUrl":"https://doi.org/10.1134/s0018151x23050061","url":null,"abstract":"<h3 data-test=\"abstract-sub-heading\">Abstract</h3><p>Mathematical model representations of the temperature effect in regions with a thermally insulated moving boundary are developed. The boundary conditions for thermal insulation of a moving boundary are formulated both for locally equilibrium heat transfer processes within the classical Fourier phenomenology and for more complex locally nonequilibrium processes within the Maxwell–Cattaneo–Lykov–Vernott phenomenology, taking into account the finite speed of heat propagation. The applied problem of heat conductance and the theory of thermal shock for a region with a moving thermally insulated boundary, free from external and internal influences, is considered. An exact analytical solution of the formulated mathematical models for equations of the hyperbolic type is obtained. Methods and theorems of operational calculus and Riemann–Mellin contour integrals are used to calculate the originals of complex images with two branch points. A mathematical apparatus for the equivalence of functional structures for the originals of the obtained operational solutions is proposed. It is shown that the presence of a thermally insulated moving boundary leads to the appearance of a temperature gradient in the region and, consequently, to the appearance in the region of a temperature field and corresponding thermoelastic stresses of a wave nature. A numerical experiment is presented and the possibility of transition from one form of analytical solution of the temperature problem to another equivalent form is shown. The described effect manifests itself both for equations of the parabolic type based on classical Fourier phenomenology and for equations of hyperbolic type based on the generalized phenomenology of Maxwell–Cattaneo–Lykov–Vernott.</p>","PeriodicalId":13163,"journal":{"name":"High Temperature","volume":"18 1","pages":""},"PeriodicalIF":1.0,"publicationDate":"2024-03-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140887192","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-03-21DOI: 10.1134/s0018151x23050012
S. I. Ashitkov, E. V. Struleva, P. S. Komarov, S. A. Evlashin
Abstract
The behavior of molybdenum under the action of load pulses of picosecond duration is studied in an experiment. Using the method of spectral interferometry in the single-exposure mode in the picosecond range, changes in the phase and amplitude of the diagnostic pulse reflected from the free surface of the sample are recorded. In a film sample of molybdenum of submicron thickness, compressive stresses reaching 89 GPa are realized and are accompanied by a significant increase in the surface reflectance.
{"title":"Shock Compression of Molybdenum under Impact of Ultrashort Laser Pulses","authors":"S. I. Ashitkov, E. V. Struleva, P. S. Komarov, S. A. Evlashin","doi":"10.1134/s0018151x23050012","DOIUrl":"https://doi.org/10.1134/s0018151x23050012","url":null,"abstract":"<h3 data-test=\"abstract-sub-heading\">Abstract</h3><p>The behavior of molybdenum under the action of load pulses of picosecond duration is studied in an experiment. Using the method of spectral interferometry in the single-exposure mode in the picosecond range, changes in the phase and amplitude of the diagnostic pulse reflected from the free surface of the sample are recorded. In a film sample of molybdenum of submicron thickness, compressive stresses reaching 89 GPa are realized and are accompanied by a significant increase in the surface reflectance.</p>","PeriodicalId":13163,"journal":{"name":"High Temperature","volume":"76 1","pages":""},"PeriodicalIF":1.0,"publicationDate":"2024-03-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140887171","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-03-21DOI: 10.1134/s0018151x2304017x
E. R. Zainullina, V. Yu. Mityakov
Abstract
The capabilities of flow visualization and gradient heatmetry are combined for the first time in studying heat transfer during condensation. The local heat flux per unit area during drop-stream condensation of water steam on the surface of a vertical plate was measured. In the drop-stream condensation mode, the average value of a significantly unsteady heat flux was about 31.2 kW/m2. The heat flux unsteady shows a complex physical picture of condensation. The results of the experiment revealed the possibility of using gradient heatmetry as a method for monitoring heat transfer during condensation.
{"title":"Study of Drop-Stream Condensation by the Gradient Heatmetry","authors":"E. R. Zainullina, V. Yu. Mityakov","doi":"10.1134/s0018151x2304017x","DOIUrl":"https://doi.org/10.1134/s0018151x2304017x","url":null,"abstract":"<h3 data-test=\"abstract-sub-heading\">Abstract</h3><p>The capabilities of flow visualization and gradient heatmetry are combined for the first time in studying heat transfer during condensation. The local heat flux per unit area during drop-stream condensation of water steam on the surface of a vertical plate was measured. In the drop-stream condensation mode, the average value of a significantly unsteady heat flux was about 31.2 kW/m<sup>2</sup>. The heat flux unsteady shows a complex physical picture of condensation. The results of the experiment revealed the possibility of using gradient heatmetry as a method for monitoring heat transfer during condensation.</p>","PeriodicalId":13163,"journal":{"name":"High Temperature","volume":"29 1","pages":""},"PeriodicalIF":1.0,"publicationDate":"2024-03-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140887176","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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