Internal Temperature Field Research Articles

Thermal Structure Strength Analysis of Nozzle of Solid Rocket Motor with the Coupled Algorithm

In order to achieve the thermal structural integrity analysis of the solid rocket motor nozzle accurately and efficiently, the multifield (flow-thermal-mechanical) coupled numerical investigation was carried out based on the mesh-based parallel code coupled interface. The numerical simulation process and finite element model of the coupled algorithm and engineering algorithm were obtained, while the physical model was simplified appropriately. The coupled interface parameters, internal flow field, temperature field, and stress field of the coupled algorithm were compared with the engineering algorithm results, and the effectiveness and accuracy of the numerical simulation were validated. The numerical investigations shown that both the temperature field and stress field obtained by the coupled algorithm were slightly lower than which obtained by the engineering algorithm. These were considered to be impacted by the Bartz empirical formula and the one-dimensional isentropic flow assumption. Further experimental investigations shown that the exterior surface temperature and strain of the nozzle throat obtained by the coupled algorithm were much closer to the experimental results, which further verified the accuracy of the coupled algorithm.

Study on Oil Flow Characteristics and Winding Temperature Distribution of Oil-immersed Transformer

The stability and effective functioning of a power grid depends upon the reliability as well as safety prospects of a transformer which is the principal component of the power system. The natural oil circulation in the oil-immersed transformer drifts the oil flow by the change in the density which is again caused by the change in temperature. But the pressure is comparatively low with respect to the oil pump causing the lower down of velocity which in turn dissipates unimpressionable heat. In this paper, a noble attempt has been made to build a natural oil circulation layer-type winding transformer based on a fluid-solid coupling heat transfer model pertaining to the internal temperature field and flow field by using the fluid mechanics’ simulation software. In the next stage, the authors have analyzed the temperature distribution, hot spot, position condition of the variable winding, the horizontal the oil channel width as well as the temperature of the winding transformer. The paper is of great significance as it examines the influence of the flow characteristics of oil channel on the winding temperature distribution. The outcome can significantly improve the structure of heat dissipation and the operating environment of the transformer.

METHOD OF LINES IN DISTRIBUTED PROBLEMS OF EXPERIMENTAL DATA PROCESSING

In many cases, the mathematical support of non-stationary thermal experiments is based on methods for solving the inverse heat conduction problem (IHCP), which include boundary thermal conditions determination, identification of heat and mass transfer processes, restoration of external and internal temperature fields, etc. However, at present, the main field of the IHCP application remains the processing and interpretation of the results of the thermal experiments. It was here where the most considerable theoretical and applied successes were achieved in methods' effectiveness and the breadth of their practical use. This paper highlights the issues of mathematical modeling of multidimensional non-stationary problems of metallurgical thermophysics.The primary research purpose aims at solving problems associated with identifying parallel structures of algorithms and programs and their reflection in the computers’ architecture in solving a wide range of applied problems. Supercomputers are currently inaccessible due to the enormous cost and service price. In this regard, a real alternative is cluster-type computing systems by which the simulation results are covered in this paper.Being a relatively new technology, cluster-type parallel computing systems are useful in solving a large class of non-stationary multidimensional problems, while allowing to increase the productivity and quality of computations. The software developed in this paper can be used to plan and process the results of a thermophysical experiment. The algorithms developed in the application program package are simply reconstructed to solve other coefficient and boundary problems of thermal conductivity. The developed algorithms for solving thermophysical problems are highly accurate and efficient: the test solution for IHCP with accurate input data coincides with the thermophysical features of the sample material. The developed software for processing the results of a thermophysical experiment is self-regulating. Moreover, it is quite merely tuned to the solution of others and, in particular, of boundary IHCP.

Three-Dimensional Electro-Thermal Analysis of a New Type Current Transformer Design for Power Distribution Networks

In recent years, the new type design of current transformer with bushing structure has been widely used in the distribution network system due to its advantages of miniaturization, high mechanical strength, maintenance-free, safety and environmental protection. The internal temperature field distribution is an important characteristic parameter to characterize the thermal insulation and aging performance of the transformer, and the internal temperature field distribution is mainly derived from the joule heat generated by the primary side guide rod after flowing through the current. Since the electric environment is a transient field and the thermal environment changes slowly with time as a steady field under the actual conditions, it is more complex and necessary to study the electrothermal coupling field of current transformer (CT). In this paper, a 3D simulation model of a new type design of current transformer for distribution network based on electric-thermal coupling is established by using finite element method (FEM) software. Considering that the actual thermal conduction process of CT is mainly by conduction, convection and radiation, three different kinds of boundary conditions such as solid heat transfer boundary condition, heat convection boundary condition and surface radiation boundary condition are applied to the CT. Through the model created above, the temperature rise process and the distribution characteristics of temperature gradient of the inner conductor under different current, different ambient temperatures and different core diameters conditions are studied. Meanwhile, the hottest temperature and the maximum temperature gradient difference are calculated. According to this, the position of weak insulation of the transformer is determined. The research results can provide a reference for the factory production of new type design of current transformer.

Finite Element Simulation of the Autoclave Curing Process of Aerospace Resin-based Composite Material

Due to the influence of the wall thickness, uneven heat transfer, and heat generation inside the resin during the molding of the composite material, the uneven temperature field distribution of the composite material is caused. This paper uses ABAQUS to perform finite element simulation on the temperature field of the forming process and obtains the distribution of the internal temperature field of the composite material. On the premise of obtaining the temperature field, through thermo-solid coupling simulation experiment, the influence of various factors on the entire curing process is compared. Based on the use of finite element simulation software, several comparative tests were carried out, and the residual stress problems in the curing process were verified by calling the stress and strain values of representative points. This article focuses on the analysis of temperature and energy data in heat transfer and 15 sets of stress-strain data under coupling action. On the premise of giving the reasons for each data, the accuracy and practicality of the data are analyzed.

Modeling the effect of temperature on strength development for cast-in-place box girder

In this paper, winter construction of cast-in-place box girder of Rongwu Expressway Project is taken as the research object. By analyzing the internal temperature field development data of box girder concrete structure and using MIDAS FEA finite element software, the simulation results are similar to those in the field. The development of concrete internal temperature field at ambient temperature 0°C and -10°C is calculated. The strength prediction of cast-in-place box girder concrete structure at lower internal temperature was carried out by using the maturity model established in laboratory test. With the decrease of ambient temperature, the internal temperature of cast-in-place box girder concrete structure decreases. The lower temperature of concrete in box girder is the edge part of the two flank plates, the windward side and the combined part of old and new concrete. Based on the maturity theory established earlier, the 5d tensile strength of different parts was calculated. Under 0°C and -10°C conditions, the minimum strength of the edge of cast-in-place box girder concrete wing plate is 47 MPa and 41.2 MPa, the minimum strength of the junction of new and old concrete is 50.5 MPa and 50.3 MPa and the minimum strength of the windward side is -52.2MPa and 51.2MPa respectively. The edge of the wing plate and the interface of new and old concrete should pay special attention to the protective insulation measures.

Research on Lithium-Ion Battery with New Flexible Electrode Materials

The thesis studied the thermal characteristics and influencing factors of the flexible electrode material lithium-ion power battery during the charging and discharging process through a combination of experiment and simulation. Studies have shown that the charge and discharge rate, ambient temperature, and state of charge will affect the battery’s thermal characteristics. The greater the charge-discharge rate, the lower the environment, and the lower the state of charge, the greater the battery’s healing power. The higher the temperature rise of the battery. As the discharge rate increases, the proportion of ohmic heat in the total heat increases, and the proportion of polarization heat and reaction heat in the total heat decreases: In the case of high-rate discharge, ohmic heat and polarization heat play a major role: environment the lower the temperature, the greater the total internal resistance of the battery, so that the greater the healing power of the battery, the faster the temperature rise of the battery. Besides, the paper proposes an internal heat source model suitable for lithium-ion batteries. The simulation results show that the proposed model can better reflect the battery’s internal temperature field during the discharge process. Simultaneously, the model is used to simulate the temperature rise of the battery when the battery is working under harsh conditions and the influence of different convective heat transfer coefficients on the battery’s thermal characteristics. The simulation shows that increasing the convective heat transfer coefficient is beneficial to lower the battery’s temperature.

Research on Simulation and Calculation of Temperature Field and Pressure of High Voltage Transformer

In order to ensure the normal and safe operation of high-voltage transformers, this paper uses oil-immersed current transformers as an example to use finite element analysis to simulate the internal temperature field of high-voltage transformers when a fault occurs, and obtain the temperature distribution of the whole body under several typical fault types. Through theoretical calculations, the pressure change at the expander on the top of the high-voltage transformer is obtained. The measured data is compared with the simulation calculation results, and the state of the high-voltage transformer at the time of failure is analyzed, and the safe and controllable temperature and pressure range of the high-voltage transformer are obtained.

Influence of grass lawns on the summer thermal environment and microclimate of heritage sites: a case study of Fuling mausoleum, China

The thermal environment and microclimate of heritage sites has been severely impacted by rapid urbanization. This study collected various meteorological measurement data as a reference for computational fluid dynamics (CFD) simulation settings. Then CFD was applied to simulate the impact of lawns on the thermal environment and microclimate of Fuling Mausoleum. We found that lawns and soil can cool the air through evaporation, and thus have a specific cooling effect on the bricked ground. Simulations with the lawns, the bricked ground temperature decreased by 1.56–17.54 °C than that simulations without the lawns at 14:00, a decrease of 2.68%–24.20%. Under normal circumstances, when the wind speed or relative humidity increased, the ground temperature dropped. Greenbelt vegetation can adjust the microclimate and human thermal comfort indicators. The consistency of the difference between the actual measurement and the CFD simulation results shows that CFD simulation can thus accurately reflect the internal temperature field distribution if the selection of simulation parameters is reasonable. Theoretical calculation and analysis, experimental measurement research, and modern computer simulation analysis methods applied together constitute a complete system for studying modern physical environmental problems and can provide reliable and economic results.

Method for Simultaneously Sensing the Internal Temperature Field and Thickness of Solid Structure under Steady Heat Conduction Condition

Method for Simultaneously Sensing the Internal Temperature Field and Thickness of Solid Structure under Steady Heat Conduction Condition

Effect of the LEHs film transmissivity on spherical hohlraum cryogenic target after the shield is removed

• Effect of the film transmissivity on spherical hohlraum cryogenic target has been investigated. • The maximum temperature difference on the target surface rises with the increase of transmissivity. • Low LEHs film transmissivity can make the temperature field in the hohlraum more stable. In this paper, computational fluid dynamics (CFD) software ANSYS Fluent was used to study the influence of Laser Entrance Holes (LEHs) film transmissivity on the indirect-drive cryogenic inertial confinement fusion (ICF) targets after the shield is removed. The results show that when LEHs film transmissivity (t LEHs ) increases from 0.01 to 1 under the steady-state calculation, the maximum temperature difference on the target surface increases by nearly 141 %. The influence of t LEHs on the target surface temperature field is particularly obvious after the shield is opened. The maximum target surface temperature rises to 3140 mK and the maximum surface temperature difference is 130 mK at the dynamic equilibrium state. However, the internal temperature field of the hohlraum is not significantly affected by Infrared radiation (IR) for t LEHs = 0.01. The maximum temperature increment on the target surface is 90 mK, and the maximum surface temperature difference is only 2.5 mK. Low LEHs film transmissivity can effectively restrain the influence of environmental radiation and keep the temperature field in a stable state in the hohlraum.

Effects of oil-air lubrication methods on the internal fluid flow and heat dissipation of high-speed ball bearings

High precision models were established to investigate airflow pattern and lubrication performance inside bearing cavity with different oil-air supply methods. The coupling technique of Level-Set function and VOF method was used to track the oil-air interface, and the migration and diffusion process of oil droplets inside bearing cavity were obtained. A high-speed oil-air lubrication test rig was designed and set up, bearing temperature rise with outer ring and lateral oil-air lubrication methods at different rotation speeds were tested and compared. Finally, combined with the internal flow and temperature field distribution, the synergistic analysis was applied and the lubricant flow and heat dissipation performance of bearing internal cavity and key areas were all estimated.

Design of Electronic Moxibustion Instrument for Umbilical Therapy and Preliminary Analysis of Temperature Field

Moxibustion has a history of thousands of years. Umbilical moxibustion achieves prevention and treatment of diseases through moxibustion at the golden section of the human body-the umbilicus. It has enough clinical practice experience. Traditional treatment methods have problems such as irritating smoke, uncontrollable temperature, experience-based, and difficult to quantify. Based on the principle of traditional umbilical moxibustion, a structural design of an electronic smokeless umbilical moxibustion instrument is proposed, which belongs to indirect moxibustion and has the advantages of smokeless, electric heating, portability, temperature monitoring and controllability. The internal heat transfer process of the moxibustion instrument is mainly heat convection and heat radiation. Based on ANSYS software, the internal temperature field of the moxibustion instrument is analyzed, and the steady-state temperature distribution and the temperature change characteristic curve of different positions with time are obtained to verify the rationality of the structural design. At the same time, lay a research foundation for the measurable and quantifiable effects of moxibustion on umbilical therapy.

Numerical simulation of the coal temperature field evolution under the liquid nitrogen cold soaking

Liquid nitrogen fracturing technology is largely based on the characteristics of coal and rock destruction caused by its low temperature to achieve the purpose of increasing permeability. The temperature field study is very important in liquid nitrogen cold soaking. In order to study the spatiotemporal characteristics of the internal temperature field inside coal under the liquid nitrogen cold soaking, the overall heat transfer law of coal is discussed. Based on the theory of heat transfer, this paper discusses the heat transfer equation of coal under the liquid nitrogen cold soaking. A cold shock simulation experiment is performed on the coal specimens during the liquid nitrogen cold soaking by the COMSOL software, and the temperature field change of the coal specimens during the liquid nitrogen cold soaking are obtained. In addition, the simulation results are compared with the experimental results of coal specimens under the liquid nitrogen cold soaking to verify the rationality of the theory and simulation analysis. The results show that the temperature field of coal specimens propagates in the form of waves under the liquid nitrogen cold soaking, which gradually decrease with increasing distance. The closer the dried coal specimens are to the liquid nitrogen boundary surface, the greater the temperature impact speed and the shorter the time required to reach a steady state. Both the surface of the coal specimen and its internal temperature change curve can be divided into three typical phases: the accelerated cooling phase, the decelerated cooling phase, and the low-temperature maintenance phase. The laboratory test results have a good correspondence with the numerical simulation results, which show that it is feasible to use numerical simulation to study the temperature field change law of coal and rock under liquid nitrogen cold soaking.

Modeling and Calculation of Coupled Heat Transfer for Heating Process of Perforating Test Tool

The perforating bullet detection experimental device is used to simulate the downhole high-temperature and high-pressure environment in which the perforating bullet performance is test. The perforating test tool is inside liquid-filled cylindrical wellbore cavity that is heated by heating wellbore wall with natural convection heat transfer. A mathematical model for unsteady heat-fluid-solid coupling heat transfer between the liquid in the wellbore cavity and the perforating test tool was established. The projection method is used to numerically solve the mathematical model, and the results of the dynamic heating evolution process of the perforation experimental device are calculated. The internal flow field and temperature field of the perforation experimental device with and without the perforating test tool in the wellbore are analyzed. Through the calculation and analysis results, it is found that the perforating test tool inside the simulated wellbore cavity has a greater influence on the flow field and temperature field.

A nonlinear analytical model of composite plate structure with an MRE function layer considering internal magnetic and temperature fields

To better exert the vibration suppression effect of magnetorheological elastomer (MRE) embedded into a composite structure with structural and functional integration advantage, this study proposes a nonlinear analytical model of such composite plate with an MRE function (MREF) layer, accounting for internal magnetic and temperature fields for the first time. Initially, a 9-layer fiber metal laminated (FML) plate with the MREF composites, consisting of two layers of metal protective skins, two layers of fiber-reinforced polymer (FRP) and one layer of MREF, is taken as an example to describe such a modelling method. Nonlinear expressions of elastic moduli of MRE and FRP involving thermal and magnetic fitting coefficients are also proposed, followed by derivation of the energy expressions of the constituent layers by the Rayleigh-Ritz method. After the free and forced vibrations are solved, the identification procedure of fitting coefficients is described and some literature results are employed to preliminarily validate this model without consideration of internal magnetic field or temperature field or both. Finally, dynamic experiments under different magnetic and temperature conditions are undertaken. The detailed comparison of the natural frequencies and resonant responses are conducted to provide a solid validation of the model developed. It has been found that enlarging the magnetic and temperature fields both facilitate the improvement of the anti-vibration performance. Also, by further increasing the shear modulus of MRE, the volume fraction of carbonyl iron particles or the thickness ratio of the MRE layer to the overall structure, a better vibration suppression capability can be obtained.

Simultaneous estimation of internal temperature field and boundary time-dependent heat flux in absorbing and scattering media using the unscented Kalman smoothing technique

Based on the future measured temperature, the Rauch-Tung-Striebel smoothing technique coupled with unscented Kalman filter is introduced to resolve the nonlinear inverse radiation-conduction heat transfer problem, which is nonlinear because of specific heat and thermal conductivity with temperature and existence of the radiative heat transfer. For the direct process, the finite volume method is applied to calculate the energy equation and radiative transfer equation is computed by the discrete ordinate method. Based on the measurement temperature signals of the right surface, the left surface time-dependent heat flux and interior temperature in absorbing and scattering medium are retrieved in near real time by using the proposed method. The different number of the future measured temperature, measurement noise, and process noise covariance are applied to examine the feasibility and reliability of the present algorithm. All retrieval results show that the Rauch-Tung-Striebel smoothing technique coupled with unscented Kalman filter is accurate and stable. Compared to the unscented Kalman filter, the accuracy of the retrieval temperature distribution is improved significantly, the deviation and oscillation of the retrieval time-dependent heat flux are also decreased substantially.

Dynamic Variation Characteristics of the Riparian Zone Temperature Distribution under Fluctuating Water Levels: Field Experiments and Numerical Modeling

Ren, J.; Chen, B.; Li, Y.; Dai, J., and Men, L., 2020. Dynamic variation characteristics of the riparian zone temperature distribution under fluctuating water levels: Field experiments and numerical modeling. Journal of Coastal Research, 36(6), 1178–1196. Coconut Creek (Florida), ISSN 0749-0208.Understanding the variations in water and heat transfer along the riparian zone under water-level fluctuations is essential for river water management, groundwater extraction, and ecosystem sustainability. The main purpose of this study is to describe the dynamics of the temperature field of the Dongting Lake beach under the fluctuation in the water level and to quantify its main influencing factors. Taking the section of Dongting Lake beach as the research object, an in situ monitoring device was used to monitor the water level, water temperature, and temperature at different depths of the beach in real time for 55 days, and the hydrothermal coupling model of the Dongting Lake beach was calibrated and verified. The main factors affecting the temperature field of the beach were determined by the global sensitivity analysis method. The results show that the fluctuation in the continental beach temperature field is small in the horizontal direction, the stratification phenomenon is obvious in the vertical direction, the temperature gradually rises with increasing depth, and the daily changes are weakened. During the high water level, the deep temperature of the beach has no obvious gradient change in the vertical direction, and as the water level of the river decreases, the external environmental temperature has a greater influence on the internal temperature field of the beach, resulting in a relatively pronounced gradient change in the deep temperature at the low water level. The results of the Morris one at a time global sensitivity analysis show that the permeability coefficient (Ks) has the greatest influence on the sensitivity of the model, followed by the porosity (n) and soil thermal conductivity (λs). The saturated moisture content (θs), residual moisture content (θr), and soil-specific heat capacity (Cs) have no significant effect on the model.

A Method for Reconstructing Internal Temperature Distribution in Solid Structure

In this paper, a method combining ultrasonic travel time measurement with inversion is proposed to reconstruct the solid temperature field. Based on the measured transient ultrasonic propagation time, the inverse problem of acoustic thermal coupling is solved directly, and the unknown equivalent heat flow is estimated. Then, the time and space distribution of the internal temperature field can be reconstructed accurately by calculating the corresponding heat conduction problems. Through the estimation of two typical heat flow function forms, the accuracy and influencing factors are simulated and analyzed. The feasibility and error of this method are analyzed through a transient verification experiment of a steel plate heated first and then cooled and a steady-state experiment in the literature. The results show that, compared with the previous methods, this method can predict the distribution of non-uniform temperature field more accurately and effectively. This method is expected to be an effective method for nondestructive testing of temperature distribution of solid structures.

Physical Modeling and Simulation of the Cooling-Down of Fused-Cast Refractories

The accurate description of the interfacial heat transfer coefficient is of great significance for the accurate measurement of the temperature field in the process of casting cooling. In this paper, the solidification process of metallic tin in refractory mould was studied by physical simulation experiment, and the on-site temperature measurement of the mold structure was carried out. According to the temperature record, the numerical simulation method is used to realize the fitting of the calculated temperature and the measured temperature. The reversible method was used to calculate the interfacial heat transfer coefficient between the casting and the mould, and then the evolution of the internal temperature field of the casting during the cooling process was determined. The results show that the melt has a large shrinkage during the cooling process, and the interface heat transfer coefficient can reach 300 W·m-2·K-1, which provides a mathematical model for the annealing process of fused-cast refractories.