Search Results (302)

This paper presents a comprehensive review of the applications and advances of numerical simulation in hydrothermal geothermal systems. It begins by outlining the global resource potential and basic characteristics of these systems while also identifying the limitations of conventional static resource assessment methods. Subsequently, it elaborates on how numerical simulation, based on thermal–hydraulic–mechanical–chemical (THMC) coupling theory, serves as an essential dynamic prediction tool for resource potential assessment, development optimization, long-term evolution forecasting, and environmental risk management. Furthermore, this review introduces commonly used simulation software and multi-field coupling frameworks and analyzes their specific applications through representative cases, including sedimentary basins, uplifted mountain systems, and high-temperature geothermal systems. Finally, current technical challenges are summarized, and future perspectives are discussed, highlighting the integration of big data and artificial intelligence and the development of digital twin technologies. Full article

To achieve proactive preventive maintenance of green and low-carbon infrastructure, this study systematically investigated the long-term durability and resistance degradation of prefabricated recycled aggregate concrete (RAC) bridge components. A 80-month multi-field coupled damage experiment under sustained flexural loading, natural atmospheric exposure, and chloride drying-wetting cycles was conducted, and an in-situ physical exposure and multi-source data-driven Support Vector Regression (SVR) dynamic surrogate model was established. Results indicate a prominent time-dependent ebb-and-flow mechanism of degradation drivers: environmental and stress boundaries dominate the early stage, whereas the material replacement rate ($R_r$) surges to become the absolute dominant driving variable (36.8%) in the ultra-long term ($t=80 \mathrm{months}$), proving the cumulative dominance of recycled aggregates. Concurrently, the residual capacity exhibits a distinct two-stage decay characterized by a 10% critical reinforcement mass loss threshold, beyond which the degradation rate of RAC100 accelerates to 1.63 times that of conventional concrete. Driven by the multi-stage injection of in-situ experimental inspection data (surface crack profiling, 2D spatial chloride profiles, and rebar mass loss), the SVR network successfully achieves a collapse-like convergence of the remaining useful life (RUL) confidence interval, precisely locking the RUL of the RAC100 component at 34.5 years within a 1.4-year error margin. This framework provides critical algorithmic support for the life-cycle safety paradigm shift in low-carbon structures. Full article

Performance prediction, process parameter optimization, and various data-driven research for low-temperature hot stamping (LTHS) processes all rely on abundant, continuous, and reliable process performance sample data. Collecting data merely through physical experiments leads to high costs, long test cycles, and limited coverage of working conditions. This paper focused on the LTHS process of 22MnB5 high-strength steel and proposed a dataset construction method that integrates experiments with finite element simulation. Firstly, LTHS experiments of 22MnB5 steel V-shaped parts were conducted under different combinations of forming temperature, in-die holding time, and stamping speed. Key performance parameters such as temperature field, forming springback angle, and Vickers hardness were measured. Secondly, a thermo-mechanical-phase transformation multi-field coupled finite element model (FEM) was established and validated using the experimental data. The results revealed that the simulation results agree well with the experimentally measured springback angle and Vickers hardness, and the FEM could accurately characterize the forming features and material property evolution throughout the whole LTHS process. On this basis, an experiment–simulation data integration framework was constructed: validated FEMs were adopted to supplement missing working conditions within the parameter space based on physical test samples. An LTHS integrated dataset with wide coverage, high data continuity, and strong usability was built by unifying variable definitions, sample organization modes, and standardized data formats. The dataset established in this paper can provide solid data support for the development of performance prediction models, process parameter optimization, and other data-driven studies of LTHS processes. Moreover, this dataset construction strategy integrating experiments and simulations can be extended to other metal plastic forming fields. Full article

Sudden collapse accidents in mine roadways occur frequently, and post-disaster emergency rescue faces major challenges in terms of safety and efficiency. Therefore, efficient demolition equipment and intelligent prediction methods are urgently needed. Abrasive waterjet technology has considerable potential for complex disaster environments owing to its high efficiency, environmental friendliness, and cold-cutting characteristics. However, its cutting performance is affected by multiple coupled factors, including jet parameters, material properties, and environmental conditions. This makes accurate prediction difficult, especially under extreme or unseen operating conditions where available samples are limited. To address this problem, this study proposes a zero-shot learning-based multi-physics coupling prediction framework for the “jet–material–environment–effect” relationship. The framework is designed to predict abrasive waterjet cutting performance under unseen working conditions. First, a multi-factor cutting-performance dataset is constructed through a hierarchical experimental design. A generative adversarial network (GAN) is then introduced to expand the sample space and compensate for the discrete nature and limited distributional coverage of the experimental data. Second, a lightweight self-attention mechanism is employed to model high-dimensional input features globally, thereby improving the model’s ability to capture complex feature interactions. Finally, a joint loss function is designed to collaboratively optimize the generation and prediction processes. The experimental results show that the proposed model achieves a prediction accuracy of 98.3% on the test set, with a coefficient of determination R² of 0.967, outperforming WOA-SVM, BP neural network, EML, and Transformer models. The inference response time is approximately 3.2 s, indicating good engineering applicability. The results demonstrate that GAN effectively expands the sample space and improves model generalization, while the LightTransformer structure provides advantages in modeling high-dimensional coupled inputs. The proposed method can provide theoretical support and technical reference for intelligent demolition rescue and cutting-depth prediction under mine disaster conditions. Full article

Autogenous shrinkage is a key factor contributing to early-stage cracking in high-performance concrete (HPC), which significantly affects structural durability and service life. As core components of HPC, supplementary cementitious materials (SCMs) can significantly improve concrete workability, mechanical properties, and durability, as well as reduce the risk of shrinkage cracking in HPC, by regulating hydration kinetics, pore structure, and microstructural evolution. The primary objective of this review is to elucidate the differential mechanisms by which different active pozzolanic materials regulate the autogenous shrinkage of HPC. This paper elucidates the patterns and mechanisms by which typical SCMs in HPC (such as fly ash, slag, silica fume, limestone powder, and nano-silica) affect the autogenous shrinkage of HPC. It analyzes the influence of key factors—including the type of SCMs, dosage, particle characteristics, water-to-binder (w/b) ratio, and composite blending on the autogenous shrinkage of HPC. Research indicates that highly reactive SCMs (such as silica fume and nano-silica) accelerate the self-drying process and increase autogenous shrinkage, whereas low-reactivity SCMs (such as fly ash) suppress autogenous shrinkage through dilution effects and by prolonging the hydration cycle. The combined use of multiple SCMs can achieve synergistic control of autogenous shrinkage and mechanical properties. Furthermore, this paper reviews existing autogenous shrinkage prediction models that account for the influence of SCMs and outlines future research directions. At the same time, this review identifies the limitations that currently exist in the research: there is a lack of a unified quantitative theoretical framework for the synergistic effects of multicomponent admixtures. The applicability of prediction models under multi-field coupling of temperature, humidity, and corrosive media is limited. And there is insufficient experimental data on the long-term shrinkage behavior of new low-carbon admixtures such as rice husk ash and calcined clay, which requires further dedicated research. Full article

The helical-channel magnetohydrodynamic (MHD) thruster is a silent underwater propulsion device free of rotating mechanical components, which fundamentally eliminates the inherent mechanical noise induced by blades and shaft systems in conventional propeller-driven thrusters. Taking a 10 T-class superconducting helical-channel MHD thruster as the research object, this work establishes a three-dimensional numerical simulation model with bidirectional electromagnetic-fluid coupling via Maxwell–Fluent, filling the research gap of systematic optimization of helical pitch angles in existing low-magnetic-field numerical investigations. A composite magnetic circuit configuration consisting of main coils and compensation coils is adopted, achieving a magnetic field uniformity of 90.13% within the effective working section and markedly alleviating magnetic field attenuation at both ends of the flow channel. Three schemes with helical pitch angles of 23.00°, 17.66°, and 14.29° are quantitatively compared to analyze the effects of helical pitch angle on current density, static pressure, total pressure, radial/axial flow velocities and three-dimensional helical streamlines. Under the rated design mass flow rate of 15.5 kg/s, the scheme with the small pitch angle of 14.29° delivers a thrust of 262.56 N and an electromagnetic efficiency of 7.23%; compared with the large pitch angle scheme of 23.00°, its thrust is improved by 28% and electromagnetic efficiency rises by 53%. Reducing the helical pitch angle extends the effective coupling distance between seawater and the electromagnetic field, optimizes the uniformity of radial current distribution, suppresses eddy currents and Joule heat loss, converts more electromagnetic energy into fluid pressure energy, and thus greatly improves the energy utilization efficiency of the propulsion system. This study provides quantitative design references for the structural optimization and engineering prototype development of low-noise superconducting underwater propulsion equipment, and supports the engineering application of helical-channel magnetohydrodynamic thrusters. Full article

Under high-Mach-number flight conditions, the combustion chambers of hypersonic vehicles encounter extreme thermal environments marked by unilateral heating, high-heat-flux density, and supercritical pressure. Traditional hydrocarbon fuel cooling often suffers from insufficient heat sinks, high-temperature cracking and coking blockages, making it difficult to meet long-endurance thermal protection requirements. Liquid metal, due to its extremely high thermal conductivity, wide liquid phase temperature range, low Prandtl number and electromagnetic pump driving capability, has become a key technology for breaking through the bottleneck of high-heat-flux thermal protection. Apart from the magnitude of heat flux, the heat-transfer time scale (such as the characteristic thermal response time of the wall and the fluid) is also crucial. During hypersonic flight, transient thermal loads can change within milliseconds, requiring rapid thermal response. Liquid metals, due to their high thermal diffusivity, have a shorter thermal diffusion time compared to hydrocarbon fuels. This review employs a systematic literature review of approaches using gallium-indium-tin alloy, GaInSn, focusing on three core directions: the flow and heat-transfer characteristics of liquid metals, the optimization of cooling micro-channels, and the application of thermal protection systems. It summarizes the research progress at home and abroad, compares and analyzes the performance differences and applicable scenarios of typical liquid-metal working fluids, and summarizes the advantages and disadvantages of existing models, structural designs, and system schemes. The research shows that liquid metals can significantly alleviate thermal stratification and eliminate coking, and deep, narrow, tree-shaped, and biomimetic micro-channels can effectively enhance heat transfer. The liquid-metal-fuel dual-channel waste heat recovery and thermoelectric power generation system has demonstrated engineering application potential. Currently, the field still faces key challenges, such as unclear heat-transfer mechanisms under extreme conditions, the lack of general heat-transfer correlation formulas, insufficient compatibility with high-temperature materials, poor miniaturization and vibration resistance of electromagnetic pumps, and low system integration. In the future, efforts should be focused on developing multi-field coupled heat-transfer models under extreme thermal environments using engineered micro-channel structures, corrosion-resistant materials, and lightweight electromagnetic pumps, promoting the research and development of integrated thermal protection, heating and power generation systems, and providing support for the development of advanced thermal management systems for hypersonic aircraft and aviation engines. Full article

Strong heterogeneity in unconventional reservoirs leads to complex fracture propagation and challenges in quantitative stimulation evaluation. This study integrates true triaxial fracturing experiments, three-dimensional CT reconstruction, multi-field coupled numerical simulation, and multiple linear regression to investigate the fracture behavior of Gulong shale (Q1, Q9) and tight sandstone under supercritical carbon dioxide (SC-CO₂) fracturing. A fracture complexity index (FCI) that incorporates fractal dimension, spatial uniformity, and aperture distribution is proposed as a quantitative metric. The results show that SC-CO₂ significantly reduces breakdown pressure and increases fracture complexity compared to water. For Q9 shale, SC-CO₂ gives a breakdown pressure of 32.91 MPa (10.46% lower than water), a fractal dimension of 2.41, and an FCI of 8.92. In tight sandstone, the SC-CO₂ breakdown pressure is 34.12 MPa, whereas water increases it to 44.50 MPa; the fractal dimension and FCI are only 2.05 and 3.40, respectively, lower than those of shale fractured with water. Multiple linear regression quantifies contribution weights: lithological weak-plane development dominates fracture complexity (41.6%), far exceeding the brittleness index. The injection rate mainly controls stimulation scale: the damage area ratio rises from 1.79% to 2.90% when the rate increases from 10 to 40 mL/min. The horizontal stress difference is key to complexity enhancement: the fractal dimension increases from 1.9230 to 1.9901 as the stress difference rises from 0 to 4 MPa. The numerical simulations further reveal the coupled thermal-hydraulic-mechanical effects. The proposed FCI-based evaluation and regression models provide a quantitative framework for optimizing SC-CO₂ fracturing design in heterogeneous unconventional reservoirs. Full article

The coal gangue waste dumps formed by open-pit coal mining are prone to low-temperature oxidation and heat storage, creating deep hidden high-temperature abnormal areas, continuously releasing toxic gases, and causing complex disasters such as slope instability and water and soil pollution. At present, self-ignition prevention and control technology is only applicable to the shallow treatment of small and flat gangue mountains. For large, deep, high-temperature waste dumps with significant height differences, multiple steps, and large areas, there is a lack of an integrated, complete set of technologies. The multi-field coupling mechanism of grouting fire extinguishing lacks engineering verification, and there is no quantitative evaluation system combining long and short periods. This paper takes the deep spontaneous-combustion high-temperature area of the No. 5 spoil dump of Lutian Coal Mine of Wuhai Energy as the research object. With the core goals of precisely delineating the fire zone space, revealing the multi-field coupling fire extinguishing mechanism of grouting, and establishing a long-term quantitative evaluation system, this study proposes a multi-process joint governance technology, along with a standardized hole filling and zoned differentiated grouting parameter system. The research systematically demonstrated technical feasibility through on-site drilling, large-scale grouting construction, and full-process quality control and error analysis. The results show that the 50 m interval geothermal gradient boreholes can accurately identify high-temperature distributions in the deep part of the dump from 0 to 34 m. The maximum combustion depth of the fourth-level and fifth-level platforms is 34 m and 20 m, respectively. A total of 1578 grouting boreholes have been constructed, with a total grouting volume of 139,289.3 cubic meters. After the treatment, the concentrations of toxic gases were all below the detection limits of the equipment, and the single cooling range reached 43% to 87%. This research refined relevant theories on the spontaneous combustion control of large-scale multi-step waste dumps, established standardized engineering processes, and provided theoretical and engineering references for the prevention and control of spontaneous combustion of solid waste in similar mines. It holds significant value for the ecological safety of mines and regional pollution control. Full article

Variable-speed operation of scroll compressors is a prevailing trend for energy saving in refrigeration systems; however, complex electromagnetic excitation induces prominent vibration and noise, yet its dominant timing, spatial distribution, and action mechanism remain unclear. An electromagnetic–structural–acoustic sequential coupling model of a scroll compressor is established and validated at three speeds (3600–6600 rpm), and a dominance identification method integrating harmonic–modal matching, variational mode decomposition, and electromagnetic correlation identification is proposed. Predicted frequencies agree well with experiments; even-order harmonics migrate linearly with speed, with harmonic–modal matching exceeding 80% at low and medium speeds. At 5400 rpm, the 24th-order harmonic (2160 Hz) coincides with mode 2 (2162 Hz), causing resonance and a threefold amplitude increase. At low and medium speeds, vibration dominance indices range between 0.68 and 0.75, while noise dominance indices decrease from 0.55 to 0.48, dropping to 0.35 and 0.28 at 6600 rpm, indicating noise source transition. Vibration at S1 through S4 shows spatial variation, and far-field noise at F1 through F4 is non-uniform. These findings clarify how electromagnetic excitation dominates the vibration and noise of scroll compressors, providing a theoretical basis for speed-segmented and zone-specific noise source identification and control. Full article

Developing Cu-based composites with excellent electrical and mechanical properties under multiphysics-coupled service conditions remains challenging. Novel Cu-Nb-Gr composites were fabricated by high-energy ball milling and High-pressure Multi-field Assisted Rapid Sintering. Experiments combined with computational fluid dynamics (CFD) and finite element method (FEM) simulations were used to investigate how Gr regulates material performance. The incorporation of 3 vol.% Gr promoted the formation of a semi-continuous Gr-rich structure coupled with an Nb-rich load-bearing structure. Under arc erosion, the semi-continuous Gr-rich structure provided efficient heat-conduction pathways, reducing the peak temperature and metal-vapor recoil force, while the Nb-rich load-bearing structure suppressed liquid–metal spattering and stabilized the molten pool. Simultaneously, Gr dynamically spread to form a continuous solid-lubricating film during sliding friction, significantly reducing the coefficient of friction and interfacial shear stress. Furthermore, under compressive loading, the semi-continuous Gr-rich structure coupled with the Nb-rich load-bearing structure alleviated interfacial elastic–modulus mismatch and extreme stress concentration, limiting macroscopic plastic deformation of the matrix. Consequently, Cu-Nb-3Gr achieved a favorable balance of arc-erosion resistance, wear resistance, and compressive performance, providing a new strategy for improving conventional Cu-based composites. Full article

Conventional resistive-type superconducting fault-current limiters (RSFCLs) rely exclusively on fault currents and temperature increases to trigger quenching, resulting in delayed fault response and excessive heat buildup under short-circuit conditions. To mitigate these limitations, this paper proposes a self-triggered, magnetic-field-excited superconducting current-limiting reactor (SCLR) integrated with a solenoidal magnet assembly. During the design and simulation phases, a segmented discretization method is employed to quantitatively characterize the gradient distribution of the external perpendicular field within the superconducting tapes and coils. This approach theoretically elucidates the mechanism by which spatially non-uniform magnetic fields influence current-limiting performance. DC short-circuit simulations show that the background magnetic field instantly reduces the critical current, rapidly transitioning the superconducting layer into a nonlinear resistive state. In contrast to the conventional topology, the proposed SCLR achieves two key performance improvements during short-circuit faults: it limits the peak fault current to just 45.9% of the value recorded with the conventional RSFCL scheme, and it reduces the maximum temperature rise by 1.4 K. The findings of this study provide a theoretical foundation and technical references for multi-field coupling modeling and structural optimization of magnetic-field-regulated current-limiting devices in DC grids. Full article

Conventional low-frequency antennas face a trade-off between miniaturization and radiation efficiency due to wavelength limitations. Although magnetoelectric (ME) antennas can overcome the electrical size constraint, existing designs lack structural tunability and performance enhancement. This paper proposes a Bézier curve-based (BCB) ME antenna that features a variable cross-section, introducing a shape tuning factor for precise geometric configuration. Using the lumped-mass method, the functional relationship between resonant frequency and the shape tuning factor is derived, establishing the theoretical basis for frequency tuning. A nonlinear multi-field coupled numerical simulation model is established for performance prediction. The BCB structure modifies internal stress distribution, enabling spatial reconstruction of magnetization modulation. The proposed design is validated by comparing the analytical model with our simulation results and literature-reported experimental data. Results show that the BCB design reduces resonant frequency and enhances converse ME (CME) coupling and far-field radiation without increasing material volume. Under clamped and free boundary conditions, the minimum resonant frequencies reach 7.2 kHz and 11.1 kHz, respectively, with CME coupling improved by 124% and 140%. When the shape tuning factor proposed in this work is set to 1/2, the proposed design degenerates into a traditional antenna with uniform cross-sections, which verifies the consistency of the established model. Full article

A fully coupled three-dimensional (3D) thermo-magneto-elastic layer-wise formulation is developed for the analysis of multilayered flat and curved panels used in aerospace and aeronautical applications. The model relies on a system of coupled second-order differential equations along the thickness coordinate z, formulated in a mixed orthogonal curvilinear reference system. The governing equations combine the three-dimensional equilibrium equations with the magnetic induction divergence equation and the heat conduction equation, providing a unified multifield framework for thermo-magneto-elastic analyses. Through a suitable definition of the curvature parameters, the same formulation can be directly applied to plates, cylinders, cylindrical panels, and shells with constant radii of curvature. The governing equations are analytically solved by adopting harmonic expansions in the in-plane directions together with the exponential matrix method along the thickness coordinate. The harmonic representation naturally satisfies simply-supported boundary conditions along the panel edges. The multilayered structure is modeled according to a layer-wise strategy, where the continuity of the selected mechanical, magnetic, and thermal variables is enforced across the interfaces between adjacent layers. Different loading boundary conditions can be assigned at the external surfaces by prescribing pressure loads, magnetic potential, transverse magnetic induction, and over-temperature. The numerical investigation is divided into two stages. First, the accuracy of the proposed formulation is verified through comparisons with thermo-magneto-elastic solutions available in the literature. Then, a comprehensive set of new benchmark results is presented by considering different geometries, thickness ratios, and loading boundary conditions. Both tabulated values and through-the-thickness distributions are reported for the most significant field variables. These benchmark results provide useful reference data for the assessment and validation of future two-dimensional and three-dimensional analytical and numerical formulations devoted to coupled thermo-magneto-elastic problems. Full article

Coal spontaneous combustion is a severe hazard in the goafs of shallow-buried coal seams, particularly under the condition of continuous surface air leakage. This study conducted an integrated experimental and 3D multi-field coupled numerical investigation based on the Huojitu Coal Mine. Experimental kinetic analyses revealed that the upper seam coal exhibits a significantly higher oxygen consumption rate and CO generation capacity than the lower seam coal, characterized by an earlier initial CO generation temperature of 40 °C compared to 60 °C. Subsequent simulations indicated that the flow field and oxygen distribution within the overlying goaf exhibit a distinct “U-shaped” profile governed by surface air leakage. The sequential extraction of the lower coal seam significantly expands the oxidation zone on the return side of the overlying goaf, leading to the formation of a critical high-temperature zone exceeding 100 °C near the return side of the setup entry. Guided by these findings, a three-phase foam technology was implemented in the field, effectively encapsulating the residual coal and drastically reducing the CO concentration at the upper corner from a peak of 221 ppm to a stable 5 ppm. The findings highlight the role of surface air leakage in coal mining and provide corresponding strategies to mitigate spontaneous combustion risks in shallow-buried coal seams. Full article