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Modulation of flow meandering in the gap of a model of a peripheral subchannel of a fuel rod assembly 燃料棒组件外围子通道模型间隙中的流动蜿蜒调制
IF 0.5 4区 工程技术
Thermophysics and Aeromechanics Pub Date : 2024-03-20 DOI: 10.1134/S0869864323060021
M. V. Shestakov, M. V. Tokarev
{"title":"Modulation of flow meandering in the gap of a model of a peripheral subchannel of a fuel rod assembly","authors":"M. V. Shestakov,&nbsp;M. V. Tokarev","doi":"10.1134/S0869864323060021","DOIUrl":"10.1134/S0869864323060021","url":null,"abstract":"<div><p>Fuel rod assemblies with tight lattice bundles are considered promising for increasing the conversion rate and heat transfer in small modular reactors. The main feature of the flow in a tight lattice rod bundle is the formation of quasi-periodic large-scale velocity oscillations in the gap between fuel rods. These oscillations enhance mixing between the subchannels and significantly increase heat transfer between the fuel rods and the coolant. The large-scale oscillations are directly related to the pitch-to-diameter (P/D) ratio of the rod bundle and the Reynolds number. In this study, we experimentally investigate the unsteady flow structure in a gap between a flat wall and three rods with a relative pitch P/D = 1.077 using time-resolved particle image velocimetry (TR-PIV) technique. The obtained TR-PIV velocity vector fields were used to analyze flow characteristics, including two- and three-dimensional mean velocity, velocity fluctuations, and Reynolds stress profiles. We also examined the influence of the Reynolds number on flow oscillations in the gap. The spatial most energy-intensive flow modes were further analyzed using the proper orthogonal decomposition (POD) method. Our results indicate the presence of several traveling waves propagating along the flow. Modulation of flow oscillations in the gap was observed. These findings are consistent with those of other researchers.</p></div>","PeriodicalId":800,"journal":{"name":"Thermophysics and Aeromechanics","volume":"30 6","pages":"983 - 994"},"PeriodicalIF":0.5,"publicationDate":"2024-03-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140173027","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Impact of wildfire on heat and moisture transfer in a seasonally thawed layer of soil studied by numerical simulation 通过数值模拟研究野火对季节性解冻土壤层中热量和水分传递的影响
IF 0.5 4区 工程技术
Thermophysics and Aeromechanics Pub Date : 2024-03-20 DOI: 10.1134/S0869864323060173
K. A. Finnikov, T. V. Ponomareva, E. I. Ponomarev, K. Yu. Litvintsev
{"title":"Impact of wildfire on heat and moisture transfer in a seasonally thawed layer of soil studied by numerical simulation","authors":"K. A. Finnikov,&nbsp;T. V. Ponomareva,&nbsp;E. I. Ponomarev,&nbsp;K. Yu. Litvintsev","doi":"10.1134/S0869864323060173","DOIUrl":"10.1134/S0869864323060173","url":null,"abstract":"<div><p>Numerical simulation was applied to the processes of heat and moisture transfer and for ice-water phase transition in a season-thawed soil layer. Analysis was performed for consequences of natural wildfire on the soil temperature and the thawing depth as a function of water retention by soil for the condition of Siberian permafrost zone. Calculations demonstrate that the permafrost thawing depth increases due to burnouts in the top organic horizon. The quantitative indexes of natural wildfire impact depend on water retention properties of the upper organic horizon of soil.</p></div>","PeriodicalId":800,"journal":{"name":"Thermophysics and Aeromechanics","volume":"30 6","pages":"1149 - 1156"},"PeriodicalIF":0.5,"publicationDate":"2024-03-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140226614","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Formulation of approximate analytical solutions for a heat transfer model for an ice layer during microwave heating 微波加热过程中冰层传热模型近似解析解的建立
IF 0.5 4区 工程技术
Thermophysics and Aeromechanics Pub Date : 2024-03-20 DOI: 10.1134/S0869864323060148
V. A. Karelin, V. V. Salomatov
{"title":"Formulation of approximate analytical solutions for a heat transfer model for an ice layer during microwave heating","authors":"V. A. Karelin,&nbsp;V. V. Salomatov","doi":"10.1134/S0869864323060148","DOIUrl":"10.1134/S0869864323060148","url":null,"abstract":"<div><p>The research considers the microwave treatment of snow-and-ice mass comprising the stages of heating and melting. A nonlinear mathematical model for two-phase Stephan problem was developed for the case of sandwich dielectrics system. We offer approximate analytical solutions that take into account the thermophysical and electrophysical properties of dielectric layers; this approach allows parametric analysis.</p></div>","PeriodicalId":800,"journal":{"name":"Thermophysics and Aeromechanics","volume":"30 6","pages":"1123 - 1130"},"PeriodicalIF":0.5,"publicationDate":"2024-03-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140172404","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Secondary flows in a flat diffuser and their significance for the formation of a turbulence field 平面扩散器中的二次流及其对形成湍流场的意义
IF 0.5 4区 工程技术
Thermophysics and Aeromechanics Pub Date : 2024-03-20 DOI: 10.1134/S0869864323060033
I. A. Davletshin, N. I. Mikheev, R. R Shakirov
{"title":"Secondary flows in a flat diffuser and their significance for the formation of a turbulence field","authors":"I. A. Davletshin,&nbsp;N. I. Mikheev,&nbsp;R. R Shakirov","doi":"10.1134/S0869864323060033","DOIUrl":"10.1134/S0869864323060033","url":null,"abstract":"<div><p>Turbulent flows in a flat diffuser are characterized by the presence of two local maxima in the profiles of longitudinal velocity pulsations. The mechanism of the formation of a turbulent flow structure in a flat diffuser was experimentally studied. For this purpose, the parameters of the flow kinematic structure in a diffuser with an opening angle of 2.5° were measured. The profiles of velocities and turbulent characteristics of the flow in typical cross sections of the channel were obtained using the optical measurement method; based on these profiles, the secondary flows in the diffuser were identified. A physical model of the formation of the turbulent flow structure is proposed. Within the framework of this model, a high degree of turbulent pulsations far from the wall is associated with the convection of turbulence from the near-wall region into the flow core by a secondary flow in the form of an averaged spiral motion of the medium in a flat diffuser.</p></div>","PeriodicalId":800,"journal":{"name":"Thermophysics and Aeromechanics","volume":"30 6","pages":"995 - 1011"},"PeriodicalIF":0.5,"publicationDate":"2024-03-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140172424","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Structure of a supersonic gas-liquid jet at high liquid concentrations 高液体浓度下超音速气液射流的结构
IF 0.5 4区 工程技术
Thermophysics and Aeromechanics Pub Date : 2024-03-20 DOI: 10.1134/S0869864323060069
V. M. Boiko, V. V. Lotov, A. Yu. Nesterov, S. V. Poplavski
{"title":"Structure of a supersonic gas-liquid jet at high liquid concentrations","authors":"V. M. Boiko,&nbsp;V. V. Lotov,&nbsp;A. Yu. Nesterov,&nbsp;S. V. Poplavski","doi":"10.1134/S0869864323060069","DOIUrl":"10.1134/S0869864323060069","url":null,"abstract":"<div><p>Supersonic gas-liquid jets of a coaxial atomizer at high liquid concentrations are studied experimentally. A complex of optical techniques is used for studying the droplet sizes: visualization and particle image velocimetry, laser Doppler anemometry, and Malvern Spraytec instrument. The research shows that the velocity and concentration profiles change with flow rate growth: an extended region with small droplet velocities appears behind the bow shock wave; in this case, the concentration decreases significantly slower than that at low liquid flow rates. A small increase in the jet energy at liquid flow rates greater than 100 l/h and a noticeable increase in the droplet size testify that the gas jet capabilities for breaking up the liquid in the described regimes are exhausted.</p></div>","PeriodicalId":800,"journal":{"name":"Thermophysics and Aeromechanics","volume":"30 6","pages":"1031 - 1042"},"PeriodicalIF":0.5,"publicationDate":"2024-03-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140228080","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
New method of molecular modeling of liquid transport coefficients 液体传输系数分子建模新方法
IF 0.5 4区 工程技术
Thermophysics and Aeromechanics Pub Date : 2024-03-20 DOI: 10.1134/S0869864323060057
V. Ya. Rudyak, E. V. Lezhnev
{"title":"New method of molecular modeling of liquid transport coefficients","authors":"V. Ya. Rudyak,&nbsp;E. V. Lezhnev","doi":"10.1134/S0869864323060057","DOIUrl":"10.1134/S0869864323060057","url":null,"abstract":"<div><p>The paper presents a method of molecular modeling of fluid transport coefficients, which is an alternative to the method of molecular dynamics. The transport coefficients are determined using fluctuation-dissipation theorems. The dynamics of molecules is calculated stochastically, with intermolecular forces being set using the appropriate created database. A distribution function of intermolecular forces is constructed and a formula is obtained for its analytical approximation. The method effectiveness is demonstrated by the example of calculating the viscosity and thermal conductivity coefficients of liquid argon and benzene. The obtained data are compared with the data of experimental and molecular dynamic modeling and their good agreement is established. With the same modeling accuracy, the developed method is shown to be significantly more time-efficient compared to the molecular dynamics method.</p></div>","PeriodicalId":800,"journal":{"name":"Thermophysics and Aeromechanics","volume":"30 6","pages":"1021 - 1030"},"PeriodicalIF":0.5,"publicationDate":"2024-03-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140225491","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
A laminar supersonic boundary layer under the conditions of diffusive hydrogen-air flame and its stability 扩散氢气-空气火焰条件下的层流超音速边界层及其稳定性
IF 0.5 4区 工程技术
Thermophysics and Aeromechanics Pub Date : 2024-03-20 DOI: 10.1134/S0869864323060124
S. A. Gaponov, S. O. Morozov, A. N. Semenov
{"title":"A laminar supersonic boundary layer under the conditions of diffusive hydrogen-air flame and its stability","authors":"S. A. Gaponov,&nbsp;S. O. Morozov,&nbsp;A. N. Semenov","doi":"10.1134/S0869864323060124","DOIUrl":"10.1134/S0869864323060124","url":null,"abstract":"<div><p>The problem of hydrodynamic stability of a boundary layer with diffusion combustion is formulated in the Dan–Lin–Alekseev approximation and at constant Prandtl and Schmidt numbers; it is reduced to solving a system of the tenth-order ordinary differential equations with homogeneous boundary conditions. With Lewis numbers equal to unity, it may be lowered to the eighth order. In the inviscid approximation, the stability problem is reduced to the integration of a single second-order differential equation.</p><p>Based on the obtained stability equations and calculations of stationary flow parameters, the stability of a supersonic boundary layer with diffusive combustion on a permeable plate with hydrogen supply through its pores is studied for the first time by direct numerical modeling. With the Mach number M = 2, the possibility of flame flow stabilization is established using calculations. It is shown that within the framework of the inviscid theory of stability, it is possible to obtain quite reliable data on the maximum degrees of the growth of disturbances.</p></div>","PeriodicalId":800,"journal":{"name":"Thermophysics and Aeromechanics","volume":"30 6","pages":"1095 - 1110"},"PeriodicalIF":0.5,"publicationDate":"2024-03-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140227286","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Simulation of heating of the sensitive element of the heat flux sensors in a high-velocity flow under variable input conditions 模拟在可变输入条件下高速气流中热流传感器敏感元件的加热过程
IF 0.5 4区 工程技术
Thermophysics and Aeromechanics Pub Date : 2024-03-20 DOI: 10.1134/S086986432306001X
I. R. Vasnev, M. A. Goldfeld, N. N. Fedorova
{"title":"Simulation of heating of the sensitive element of the heat flux sensors in a high-velocity flow under variable input conditions","authors":"I. R. Vasnev,&nbsp;M. A. Goldfeld,&nbsp;N. N. Fedorova","doi":"10.1134/S086986432306001X","DOIUrl":"10.1134/S086986432306001X","url":null,"abstract":"<div><p>The paper presents the results of numerical simulations of high-velocity turbulent air flows in a plane channel with a variable cross section exhibiting sudden expansion with allowance for coupled heat transfer with copper plates modeling the sensitive elements of heat flux sensors. The simulations are performed for conditions of a high-enthalpy short-duration wind tunnel whose specific features are the short duration of the test regime and unsteady “falling” conditions at the model channel entrance. The wave structure of the supersonic flow, which affects the heat fluxes at the walls, is analyzed for various Mach numbers at the model channel entrance. The numerical algorithm is validated on the basis of experimental data on heating of the sensitive elements of heat flux sensors for unsteady input conditions at the channel entrance. The influence of the Mach number, static parameters, and stagnation parameters on the rate of heating of the sensitive elements located at various points in the channel is studied numerically. The heat fluxes calculated under constant and “falling” conditions at the channel entrance are compared. It is shown that the accuracy of heat flux modeling can be increased by taking into account the intensity of oscillations of the flow parameters and their changes along the channel.</p></div>","PeriodicalId":800,"journal":{"name":"Thermophysics and Aeromechanics","volume":"30 6","pages":"967 - 982"},"PeriodicalIF":0.5,"publicationDate":"2024-03-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140172413","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Experimental study of sizes and velocities of the droplets produced by water injection system with compressed-air atomizer into the intake manifold of an internal combustion engine applying the optic methods 应用光学方法对带有压缩空气雾化器的水喷射系统在内燃机进气歧管中产生的液滴的大小和速度进行实验研究
IF 0.5 4区 工程技术
Thermophysics and Aeromechanics Pub Date : 2024-03-20 DOI: 10.1134/S0869864323060136
M. D. Garipov, A. G. Khafizov, R. F. Zinnatullin, A. A. Melkov, V. A. Shayakhmetov, O. A. Gobyzov
{"title":"Experimental study of sizes and velocities of the droplets produced by water injection system with compressed-air atomizer into the intake manifold of an internal combustion engine applying the optic methods","authors":"M. D. Garipov,&nbsp;A. G. Khafizov,&nbsp;R. F. Zinnatullin,&nbsp;A. A. Melkov,&nbsp;V. A. Shayakhmetov,&nbsp;O. A. Gobyzov","doi":"10.1134/S0869864323060136","DOIUrl":"10.1134/S0869864323060136","url":null,"abstract":"<div><p>The paper studies the quality of water spraying by system with a compressed-air atomizer designed for water injection into the intake manifold of an internal combustion engine. The system consists of a two-cylinder piston compressor providing compression of water-air mixture in the working chambers. The piston compressor has connection to the atomizer through long channels. The droplet sizes were measured through automatic image processing by the Shadow Photography method. The droplet velocity field was measured by 2D-PIV method. Experimental results demonstrated that the injection system offers a high quality of atomization for the air/water mass ratio higher than 0.46. The Sauter mean diameter was no more than 31.1 µm.</p></div>","PeriodicalId":800,"journal":{"name":"Thermophysics and Aeromechanics","volume":"30 6","pages":"1111 - 1121"},"PeriodicalIF":0.5,"publicationDate":"2024-03-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140225972","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Thermal conductivity of Novec 7100 in vapor phase 消费及工业专用化学品 7100 在气相中的导热率
IF 0.5 4区 工程技术
Thermophysics and Aeromechanics Pub Date : 2024-02-13 DOI: 10.1134/S0869864323050116
E. P. Raschektaeva, S. V. Stankus
{"title":"Thermal conductivity of Novec 7100 in vapor phase","authors":"E. P. Raschektaeva,&nbsp;S. V. Stankus","doi":"10.1134/S0869864323050116","DOIUrl":"10.1134/S0869864323050116","url":null,"abstract":"<div><p>Thermal conductivity of a Novec 7100 fluid sample was measured by the steady-state method of coaxial cylinders. Experiments were performed in the temperature range 350–385 K and pressure range 0.12–0.21 MPa. The error for experimental data on thermal conductivity is about 1.5–2.5 %. The error in measuring temperature and pressure was less than 0.05 K and 4 kPa, correspondingly. The general equation for calculating the thermal conductivity as a function of pressure and temperature was formulated. Thermal conductivity was defined for the ideal gas state. A previously developed approach was tested in application for a single-measurement prediction of thermal conductivity.</p></div>","PeriodicalId":800,"journal":{"name":"Thermophysics and Aeromechanics","volume":"30 5","pages":"935 - 938"},"PeriodicalIF":0.5,"publicationDate":"2024-02-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139772369","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
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