Multi-physical Field Coupling Research Articles

Study on the Electrothermal Properties of Cu-CNT TSV Interconnects under Multi-physics Field Coupling

Study on the Electrothermal Properties of Cu-CNT TSV Interconnects under Multi-physics Field Coupling

Influence of operating parameters on metal flow and thermal characteristics in an EMBr-single-ruler controlled CSP funnel-shaped mould

Electro-magnetic brake (EMBr), as a necessary technique to adjust the metal flow within the mould, has been extensively applied in the continuous casting (CC) production. The EMBr technique, if appropriately applied, can take the benefit of braking effect to weaken jet impingement effect, suppress fluid disturbance and stabilize surface fluctuation. As a result, to obtain a reasonable flow pattern within the CC mould, the braking performance of EMBr technique needs to be flexibly adjusted according to the variation of operational parameters. In this article, to obtain a braking performance of a commonly used EMBr-single-ruler technique within an optimal range, the effect of operating parameters on the metal liquid flow and thermal characteristics in a compact strip production (CSP) thin slab mould is described through a 3-D mathematical modeling of multi-physical field coupling. The results illustrate that the braking performance of the EMBr-single-ruler device is weakened with the increase of the casting speed or the mould width. For the effect of the casting speed and mould width on the metal flow with the application of an EMBr device, an optimum braking performance of the EMBr-single-ruler device can be obtained under the matching parameters of a magnetic induction intensity of 0.30 T and a casting speed of 4.5 m ∙ min‒1 together with a mould width of 1500 mm. Relative to the absence of the EMBr-single-ruler device, the maximum surface fluctuation height is controlled at 6.2 mm, and the mean surface temperature is raised to 1803.6 K. Based on these findings, we conclude that the proper utilization of the EMBr-single-ruler device can avoid the entrainment of flux powder and improve the melting performance of flux powder.

Multi-physical field simulation calculation and analysis of simulated high-level waste liquid spray calcination.

Aiming at the independent research and development of a simulated high-level waste liquid spray calcination transformation treatment test device, a three-dimensional multi-physical field model of spray calcination was established by means of finite element analysis method. In this paper, the simulated high-level waste liquid is a mixed solution of nitrate solution and sucrose. The main chemical components of nitrate dissolution are HNO3 and NaNO3. The process of evaporation and calcination of high-level waste liquid to form oxides is also called the pretreatment of high-level waste liquid or the conversion of high-level waste liquid. In this experiment, the atomized droplets sprayed at high speed are evaporated, dried and calcined in turn in the calciner to obtain the calcined product. The distribution law of temperature flow field and chemical reaction state and results inside the test device were revealed by simulation calculation. The results show that under the condition of multi-physical field coupling, the chemical reaction temperature has an effect on the yield of the product. The temperature is positively correlated with the product concentration, and the effect of temperature on the yield of NO2 is greater than that of Na2O. At the same time, in this chemical reaction, the concentration of reactants (NaNO3 and HNO3) had a positive correlation with the concentration of main products (NO2 and Na2O). However, the rate of increase in the concentration of the main products (NO2 and Na2O) decreased with the increase of the concentration of the reactants (NaNO3 and HNO3).

Research on simulation method of multiple time scales dissolution process in tube electrode pulse electrochemical machining

Tube electrode pulsed electrochemical machining (TE-PECM) has received widespread attention as an electrochemical perforation technique that is widely used for machining deep small holes/oblique small holes such as air film holes in blades. However, the TE-PECM process is characterized by complex multi-physics field coupling relationships and multiple time scales for multi-physics interactions, making the simulation of the pulsed electrolytic processing process computationally huge and difficult to perform. To accurately describe the multi-physical field coupling relationship for pulsed electrochemical processing. In this paper, a k-ε gas-liquid two-phase flow model has been introduced to model the interpolar gas-liquid two-phase flow field variation law, and on this basis, a coupled multi-physics field model for pulsed electrochemical machining processing is established to provide an accurate description of the interpolar multi-physics interaction mechanism. A quasi-steady-state iterative simplification algorithm based on heat source averaging is proposed to solve the problem that the time scale span of the dissolution process leads to a huge amount of simulation calculations. The simulation analyzes the dissolution characteristics at the micro time scale and macro time scale and compares them with the full precision method. The results show that the simulation accuracy of the two methods is the same, but the simulation calculation time of the simplified algorithm is reduced by two-thirds. The experimental platform was designed and built to carry out a series of experiments under different processing times, and the results effectively verified the correctness of the simulation method.

Electromagnetic–thermal field coupling in tissue ablation: The EAES design and optimization

The coupling control of multi-physics fields has become a focal issue in the engineering domain, especially for achieving a more precise simulation and prediction of physical phenomena. This approach plays a crucial role in enhancing design efficiency and optimizing material selection. Focusing primarily on the controllability between microwave and temperature fields, the Emission Area Extension Structure (EAES) is a novel structure in response to the demand for high circularity in microwave ablation. Finite element analysis was employed to examine the distribution characteristics of electromagnetic and temperature fields in liver tissue under varying power and time conditions. Comparative analyses were conducted to evaluate the impact and performance of the EAES vs traditional structures in ablation. Incorporating the EAES into conventional ablation needles allows for a more concentrated distribution of the electromagnetic field without altering the needle diameter. In the simulation of tissue ablation, the circularity of ablation increased by 10%, while water-cooling efficiency increased by 11%. The introduction of EAES, while maintaining its minimally invasive characteristics, effectively enhanced the controllability of conformal ablation. Furthermore, a mathematical model was developed to serve as a theoretical basis for selecting optimal preoperative parameters, incorporating conditions such as ablation time, power, range, and circularity. Overall, by conducting a multi-physics field coupling analysis on microwave ablation needles and proposing the EAES solution, this study aims to enhance the predictability, controllability, and safety of conformal ablation.

Research on temperature rise characteristics and hot spot temperature inversion method of oil-immersed transformer based on coupling of magnetic-fluid-thermal field

The hot spot temperature is an important factor affecting the operation state and insulation life of oil-immersed transformer. It is of great value to carry out multi-physical field coupling simulation research on magnetic-fluid-thermal field of oil-immersed transformer and accurately calculate and predict the hot spot temperature of transformer for transformer service life evaluation. In this paper, the oil immersed transformer is taken as the research object, and five characteristic parameters of the hysteresis model are obtained by using PSO optimization algorithm according to the experimental magnetic characteristics data of the core material and the classical J-A hysteresis model, A 3D simulation model of magnetic-fluid-thermal field is established based on the electrical and structural parameters of the oil-immersed transformer. Combined with the magnetic characteristics of the core material, the thermal field and the surrounding fluid distribution of the transformer core and winding are obtained by two-way coupling method. On this basis, in order to accurately reflect the correlation between the hot spot temperature of the transformer winding and the temperature of the oil tank wall, the selection position of the characteristic temperature point of the transformer tank wall is determined by streamline analysis method, and the hot spot temperature of the oil-immersed transformer is retrieved by support vector machine method. The results show that the prediction accuracy of the hot spot temperature reaches 0.998, and the inversion method has a high enough accuracy. It provides theoretical basis and technical support for real-time monitoring of hot spot temperature in oil-immersed transformer windings.

Structure optimization design of gasket test rig based on response surface model

In order to enhance the temperature regulation response speed of the gasket test rig and reduce the hysteresis of the temperature control system, structural optimization is implemented in the hardware part of the test rig. Firstly, a multi-physical field coupling method is employed for comprehensive performance testing of high-temperature and high-pressure gaskets, establishing a heat-fluid-solid coupling simulation and analysis model based on ANSYS. Then, internal temperature distribution of the gasket test device is calculated considering initial and boundary conditions. Next, data is collected using Latin hypercube sampling method, and optimal structural parameter combinations are determined through a multi-objective optimization approach utilizing response surface method and improved genetic algorithm. Finally, collected data is further utilized with response surface method and improved genetic algorithm multi-objective optimization technique to obtain optimal structural parameter combinations for the gasket test device which are verified by heat-fluid-solid coupling simulation. The temperatures tested before and after optimization are analyzed for comparison purposes. The results demonstrate that optimized gasket test rig significantly enhances its temperature control performance.

Thermal Stress Analysis and Fatigue Life Assessment of Bridge Structures under Multi-Physical Field Coupling

Thermal Stress Analysis and Fatigue Life Assessment of Bridge Structures under Multi-Physical Field Coupling

Multi-source microwave heating temperature uniformity study based on adaptive dynamic programming

Abstract In view of the multi-physical field coupling and time-varying characteristics of the microwave heating medium process, how to dynamically plan the state characteristics of multiple microwave sources and optimize the material temperature uniformity becomes the focus of this article. To this end, first, algebraic graph theory is used to construct the multiple microwave sources as a multi-agent system, and a perfect communication topology is established to ensure the transfer and sharing of information. Second, according to the real-time temperature distribution of the material, an event-triggered adaptive dynamic planning algorithm is used to co-operate with the power input of the multiple microwave sources to ensure that no new hot spots are generated during the optimization of the temperature distribution using the self-organizing properties of the medium. Finally, a numerical calculation model for optimizing a mixture of integer and continuous variables is solved using the finite-element method. The experimental and numerical results show that this article improves the temperature uniformity by 32.4–73.5% and the heating efficiency by 14.3–39.4% compared to the generic heating model, and the feasibility of the method is verified by the different shapes of the heated material.

Research Status and Development Trend of Cylindrical Gas Film Seals for Aeroengines

High-performance aeroengine design is an important component of modern industry, and advanced sealing technology is a key technology to meet the engine fuel consumption rate, thrust-to-weight ratio, pollutant emission, durability, and lifetime. Reducing the internal airflow leakage of the engine through a sealing technology can improve the performance and efficiency of the engine. In this paper, the typical sealing technology for an aeroengine is introduced in more detail, including the structural characteristics and use limitations of the labyrinth seal, brush seal, honeycomb seal, gas film face seal, and cylindrical gas film seal. It focuses on the development history, typical structure type, working principle, basic technology research method, steady-state performance, dynamic characteristics, multi-physical field coupling, structural deformation, experimental testing, processing technology. Finally, it summarizes the problems and future development trends of the current application of the cylindrical gas film seal in aeroengines, and points out that the seal performance test and evaluation based on advanced composite sensor technology and the innovative design of the seal based on new material, a new principle, and a new structure will be the new research direction.

Bending-torsional coupling vibration characteristics of asynchronous motorized spindle considering electromechanical coupling and multi-excitation effect

For the asynchronous motorized spindle directly driven by the induction motor, the load-dependent slip ratio determines that its transient characteristics are sensitive to load. For the accurate evaluation of transient characteristics, it is necessary to deeply analyze the bending-torsional coupling vibration characteristics of the asynchronous motorized spindle with the non-ideal energy source. In this work, starting from energy conservation and clarifying the multi-physical field coupling mechanism, the bending-torsional coupling dynamic model is developed. Considering the speed fluctuation, the mass eccentricity excitation is deconstructed to explore its contribution to the coupling vibration. From the load-displacement relationship, the unbalanced excitation experienced by the journal from the bearing is modeled, considering the friction. According to the T-type equivalent circuit and mechanical characteristics of the induction motor, the electromagnetic torque considering power conservation is obtained. Furthermore, combined with Maxwell's stress formula, the electromagnetic excitation from electromagnetic torque and magnetic pull is obtained, considering the tangential and normal magnetic stress. Based on the projection and synthesis of forces, the semi-empirical mechanical cutting force model is employed to calculate the milling load. And a numerical algorithm for the fast acquisition of state-dependent delay is proposed. In particular, to reasonably characterize the energy characteristics in the system, the influence of structural vibration as an energy sink on the multi-physical field composed of mechanical, electromagnetic, and thermal fields is explored from the energy conservation. The proposed model was validated experimentally. The effects of electrical and mechanical parameters on the response are numerically discussed.

Research on Magnetic-Thermal-Force Multi-Physical Field Coupling of a High-Frequency Transformer with Different Winding Arrangements

In order to clarify the magnetic-thermal-force changing rule of high-frequency transformers under different winding arrangements, this paper tests the magnetization and loss characteristics of nanocrystalline materials at different temperatures, and based on the magnetization and loss data, establishes a magnetic-thermal-force coupling calculation model of 15 kVA, 5 kHz nanocrystalline high-frequency transformers, and calculates and analyzes the magnetic flux density, loss and temperature rise distributions of high-frequency transformers with three different winding arrangements under no-load and short-circuit conditions, respectively. Through comparative analysis, it was found that under no-load conditions, the cross-transposition of winding has less influence on the magnetic flux of the high-frequency transformer core, but it can reduce the iron-core loss and transformer temperature rise. The cross-transposition of winding under short-circuit conditions can significantly reduce the leakage magnetic field strength of high-frequency transformers; complete cross-transposition weakens the high-frequency transformer losses and temperature rise better than partial cross-transposition. According to the winding current density and core leakage field distribution under short-circuit conditions, we calculated and analyzed the distribution of its the axial and radial electromagnetic forces. The results show that the axial electromagnetic force causes the winding to be squeezed from both ends to the middle, the radial electromagnetic force causes the primary winding to shrink inward and the secondary winding to expand outward, so cross-transposition can greatly reduce electromagnetic force and weakening the deformation of the winding. Therefore, high-frequency transformers of winding cross-transposed should be used in actual projects to reduce transformer temperature rise and improve efficiency and security. This research has theoretical significance for the multi-physical field coupling of high-frequency transformers and its structural design.

Evaporation Properties of Water through Floating Porous Structures for Desalination

The floating porous structure consists of an optical absorption layer, a porous layer, and an insulating layer. Water is pumped through a porous structure to the top absorption surface for evaporation. A numerical model of interfacial evaporation of floating porous structure is established. A multiphysical field coupling model for heat transfer, flow, and mass transfer within porous structures is simulated. The transient temperature response, evaporation flux, and vapor concentration distribution inside the structure are calculated. Effects of porous structure characteristics, such as size and porosity, on evaporation performance are discussed. With the increase of structure radius, the evaporation amount increases gradually, but the evaporation per unit area decreases with the radius. With the increase of the structure height, the evaporation amount and the evaporation flux decrease, but the decrease is relatively small. The porosity of the porous layer ε1 has a significant effect on the evaporation performance. The increase of ε1 is beneficial to the evaporation of water. When ε1 < 0.3, the effect of the porosity of insulation layer ε2 on the evaporation performance can be neglected.

Micromagnetic simulation of Nd-Fe-B demagnetization behavior in complex environments

With the continuous expansion of the application range of Nd-Fe-B permanent magnetic materials, it becomes increasingly necessary to understand their magnetic performance under different working conditions. Currently, there is limited research on the magnetization characteristics of Nd-Fe-B in complex environments. In this study, a theoretical model considering demagnetizing field, thermal effects, and force-magnetic coupling was established to investigate the demagnetization behavior of Nd-Fe-B under the combined influence of temperature, pressure, and magnetic field. To address the high cost and implementation difficulties associated with demagnetization experiments in complex environments, as well as the limitations of general hysteresis models in terms of research scale, a micromagnetic numerical simulation method incorporating the theoretical model was adopted. The simulation was performed using COMSOL Multiphysics, which allows for multi-physics field coupling. The demagnetization behavior of Nd-Fe-B in complex environments was calculated. The demagnetization curves of Nd-Fe-B under different combinations of temperature, pressure, and magnetic field were obtained. From the perspective of magnetic moment motion, the demagnetization mechanism of Nd-Fe-B was analyzed. Furthermore, the variations in coercivity, Curie temperature, and critical demagnetizing pressure of Nd-Fe-B in complex environments were summarized. These findings provide theoretical guidance for the application of Nd-Fe-B permanent magnetic materials in complex working environments.

Study of noise and structural characteristics of twin-screw air compressor based on multi-physical field coupling

For the problems of high noise and low efficiency of twin-screw air compressor, the mutual coupling effect of noise and structure for the twin-screw air compressor is studied by using acoustic-solid coupling technology. The simulation model of acoustic-structural coupling of twin-screw air compressor is established. Combining acoustic wave theory calculation with structural characteristics, the sound pressure level distribution and structural deformation law of different tangent planes of the shell at different frequencies under external excitation are studied. The results show that when the frequency is different, the more intensive the acceleration distribution on the shell surface is, the greater the sound pressure level is. At the same frequency, as the incident pressure wave increases, the deformation on the shell also increases, and the maximum shell deformation and the maximum sound pressure level both appear around 2000 Hz. As the frequency increases, the acceleration distribution on the surface of the shell becomes more denser and the sound pressure level becomes larger.

Liquid film parameter measurement based on thermal distribution sensor in horizontal annular flow

Liquid film is an important carrier of mass and heat transfer in annular flow, and the parameter detection of which plays an important role in the energy metering of natural gas production processes and the safe and reliable operation of cooling and heating systems. In this paper, a liquid film velocity equation is derived based on the analysis of the heat balance equation between the liquid film and tube wall. According to the constant power principle, the thermal distributed flow measurement sensor is designed by using the multi-physical field coupling simulation technique According to the momentum balance equation of the Laurinat model, considering the pump mechanism of the disturbance wave and using magnitude comparison and stress balance, a liquid film thickness circumferential distribution model in the horizontal annular flow is proposed. Utilizing the model and designed sensor, the liquid film thickness of four locations (0°, 90°, 180°, 270°) measurements are obtained for 64 horizontal annular flow conditions. Laboratory results indicate that the mean absolute percent error of the model is 32.66% and the 82.81% relative error is within the ±30% error band.

A study on the coupling mechanism of hydrate dissociation-seepage-heat transfer induced by suction anchor installation in marine sediments

The suction anchor base has been widely used in marine engineering as an innovative and efficient foundation for marine structures. However, prior research endeavors have neglected to account for the influence of hydrate dissociation within the seabed sediments on suction anchors' negative pressure installation process. This paper elucidates the intricate coupling mechanism of hydrate dissociation, seepage, and heat transfer within marine sedimentary layers, all of which are induced by installing suction anchors. Employing a multi-physical field coupling methodology, numerical simulations were conducted to analyze the influencing factors and spatiotemporal evolution of hydrate dissociation and the impact of hydrate dissociation on seepage and pressure fields. The results indicate that the increases in negative installation pressure, penetration depth, and stratigraphic sensible heat promote hydrate dissociation. The hydrate dissociation enhances seepage, reduces the pressure gradient in the anchor, and decreases the suction anchor sinking force. Consequently, this research holds practical implications for guiding suction anchor installation within seabed characterized by buried hydrate.

The development of nuclear reactor three-dimensional neutronic thermal–hydraulic coupling code: CorTAF-2.0

Numerical reactor technology is the development direction of advanced nuclear energy system simulation, which has the ability of high-fidelity multi-physical field coupling calculation. The thermal–hydraulic and neutron physics fields in reactor core exhibit strong feedback relationships. Establishing the neutronic thermal–hydraulic coupling calculation model of the whole core “pin-by-pin” is the key technology for the development of numerical reactors. In this study, the neutron diffusion analysis model and cross-section database have been developed based on the open source CFD platform OpenFOAM. The three-dimensional neutron diffusion analysis model based on the finite volume method has been validated by benchmark problems. By integrating the neutron diffusion analysis model and cross-section database into nuclear reactor core three-dimensional thermal–hydraulic characteristics analysis code CorTAF, the strongly coupled neutronic thermal–hydraulic coupling analysis code CorTAF-2.0 has been developed. The neutronic thermal–hydraulic coupling phenomena in the full core of AP1000 have been simulated using CorTAF-2.0, yielding the sub-channel level parameters distribution of the whole core. This work offers valuable references for reactor full-core neutronic thermal–hydraulic coupling analysis.

Experimental Analysis of Third Harmonic on Zero Line Heating Influence Based on COMSOL

In the study of zero-line heating fire hazard caused by the third harmonic, the harmonic content in a high harmonic incidence place is measured, and an indoor physical experiment platform is built as well. Based on the experimental platform, the third harmonic heating experiment on zero lines is carried out with different wire diameters. The heating pattern of zero lines under different working conditions is obtained, which could provide a certain experimental basis for electrical fire prevention in public places. Based on the COMSOL multi-physical field coupling simulation software, the third harmonic heating model of zero line is established, and the curve of temperature distribution gradient and zero line temperature is obtained. The comparison between simulation results and experimental results verifies the accuracy of the simulation model. It provides a theoretical method for a reasonable selection of zero-line diameter, arrangement of zero line layout, and prevention of electrical fire.

Simulation Study of Transient Eddy Current Effect in 3T Animal Gradient Coil

In the process of high-field magnetic resonance imaging (MRI), the eddy current modeling and simulation of the cold screen and metal parts are not highly accurate. To solve this problem, this paper uses the target field method to design a 3T animal gradient coil model. To get more realistic simulation results, a complex model including a gradient system, cryogenic vessel, cold screen, epoxy resin, and temperature holes was constructed. The model was refined using the finite element method, and the effects of eddy currents induced by the gradient coil on the cylindrical cryogenic container and cold screen in the superconducting magnetic resonance instrument under the state of multi-physical field coupling were simulated. The model effectively reflects the transient eddy current distributions on the cold screen and cryogenic vessel in the MRI system and their time-dependent temperature rise effects.