Three-dimensional Coupling Research Articles

Numerical analysis of hydrogen atom diffusion and trapping at an unconstrained dent on pipelines

In this work, a three-dimensional finite element-based mechanics-diffusion coupling model is developed to determine the stress/strain distribution and hydrogen (H) atom concentration at an unconstrained dent on an X52 steel pipe which is to be used for transport of high-pressure hydrogen gas. Both von Mises stress and equivalent plastic strain concentrations and a high hydrostatic stress gradient exist at the dent. The distribution of H atom concentration coincides with that of the hydrostatic stress. The maximum H atom concentration in the steel lattice locates at the dent bottom, while the distribution of the H atom concentration at metallurgical traps is consistent with that of the equivalent plastic strain. A competitive effect exists between the hydrostatic stress and the plastic strain on the H atom distribution. At low initial H atom concentrations (e.g., 0.001 mol/m3), the equivalent plastic strain dominates the distribution of H atoms. At high initial H atom concentrations (e.g., 0.1 and 1 mol/m3), the hydrostatic stress is more important to determine the distribution of H atom concentration. As the dent depth increases, both the von Mises stress and plastic strain at the dent increases, while the total H atom concentration decreases due to decreased hydrostatic stress. When the internal pressure increases from 5 MPa to 15 MPa, there are slightly increases in von Mises stress, equivalent plastic strain and the total H atom concentration.

Observer-based robust impact angle control three-dimensional guidance laws with autopilot lag

Considering an air-based missile intercepting maneuvering target with desired impact angles, robust guidance laws with autopilot lag in three-dimensional coupling space are presented in this paper. First, combining the fixed-time stability theory and adaptive sliding mode control technique, a novel dual-layer adaptive fixed-time sliding mode disturbance observer is proposed to estimate the unknown target maneuver. The proposed disturbance observer releases the requirement of information on either the target maneuver or its derivative. To achieve interception with the desired impact angles, a novel guidance law based on the nonsingular terminal sliding mode (NTSM) with an exponent coefficient is provided. The proposed control framework prevents singular problems and ensures the fixed-time stability of the guidance system. In addition, autopilot dynamics are taken into consideration, and the dynamics surface control (DSC) method is used to address the nonlinear static feedback system. Meanwhile, the improved fixed-time differentiator is used to acquire the derivative of virtual control laws. This prevents the inherent “differential explosion” of the backstepping technique. The uniform boundedness of the closed-loop system is demonstrated via the Lyapunov method. Finally, numerous numerical simulations are carried out, and the simulation results verify the effectiveness of the proposed guidance laws.

Weak form quadrature element analysis of spatial geometrically exact composite beams with torsional warping

Spatial thin-walled laminated composite beams under large deformations with torsional warping effects are studied. A novel two-dimensional cross-section model for composite beams with shear and torsion-warping deformations is proposed wherein the three-dimensional warping and coupling effects caused by inhomogeneous anisotropic materials are considered. A weak form quadrature element formulation is established for nonlinear analysis of geometrically exact composite beams with torsional warping and shear deformations. By combining the two-dimensional cross-section model and the nonlinear one-dimensional beam model, the three-dimensional stress and strain fields can be obtained. Numerical examples are provided to investigate the torsional warping effects and verify the effectiveness of the present formulation. Results of the present beam formulation which are achieved at a significantly lower computational cost are in excellent agreement with those of shell and solid models of commercial codes.

Three-dimensional nonlinear coupling vibration of drill string in deepwater riserless drilling and its influence on wellbore pressure field

Three-dimensional nonlinear coupling vibration of drill string in deepwater riserless drilling and its influence on wellbore pressure field

A Review of the Computational Investigation of Three-Dimensional Transient Magneto-Thermal Coupling Characteristics of Electromagnetic Railgun Armature and Rail in High-Speed Sliding Electrical Contact

In order to investigate the dynamic process of electromagnetic field distribution, temperature change and the deformation during the launching process of electromagnetic railgun. It is necessary to conduct a three-dimensional coupled electromagnetic-temperature-structure analysis of the rail and armature, which requires the establishment of the corresponding multi-physics field model and the use of appropriate software and algorithms to complete the relevant simulation calculation and solution results. Based on this, this paper summarizes the current domestic and foreign research methods for multi-physics field characteristics under sliding electrical contact conditions, analyses the advantages and disadvantages of each method, and focuses on the updates of the three-dimensional finite element program EMAP3D based on Lagrangian description and the advantages of multi-field coupling. Finally, several considerations and operable spaces for multi-physics field coupling simulation are summarized to provide technical support for subsequent studies on multi-physics field characteristics for high-speed sliding electrical contact condition.

Study on iterative algorithm of full plate cross-flow and counter-flow printed circuit heat exchanger for fluoride-salt-cooled high-temperature advanced reactor

In the concept of Fluoride-Salt-cooled high-Temperature Advanced Reactor (FuSTAR), the Printed Circuit Heat Exchanger (PCHE) is mainly considered in its supercritical carbon dioxide (S–CO2) Brayton cycle secondary loop. The design of the PCHE is based on the property of working fluid provided by the Brayton cycle system design. Therefore, a fast and iterative PCHE design method is required. In this study, a mathematical model based on Picard's iterative method is proposed. The model can solve full plate temperature field with complex boundary conditions and initial values including cross-flow and counter-flow PCHE in parallel. Based on FuSTAR Brayton cycle design conditions, three sizes of cross-flow and counter-flow PCHEs are simulated respectively by the mathematical model. Compared with Computational Fluid Dynamics (CFD) models, a one and three-dimensional coupling model and a three-dimensional model, the mathematical model reduced the computing time from 1 to 10 h to 1–10 s, and the maximum temperature mean deviation is 18.6% for the smallest size case because of the edge effect and local disturbance, but 8.4% for other size. Taking secondary loop recuperator design as example, the computing speed and accuracy of the mathematical model can meet the design requirements of FuSTAR PCHE.

Performance analysis of sCO2 tube with high non-uniform heat flux: Thermal-fluid-structural evaluation and optimization

A supercritical carbon dioxide (sCO2) tube is an important component in a sCO2 power system for a wide range of heat sources. The sCO2 tubes experience high temperature and pressure with high non-uniform heat flux when fossil fuel and solar energy are used as heat sources. Herein, a novel tube structure is proposed to match the circumferential thermal resistance with the non-uniform heat flux by changing the Eccentricity. A three-dimensional multi-physical coupling model was constructed to compare the proposed structure with a conventional tube. The fluid dynamics, thermal stress, and coupled heat transfer characteristics were analyzed, and the key working parameters were explored. The maximum temperature of the proposed structure was effectively reduced by 13–36 K and the maximum thermal stress was significantly reduced by approximately 25–33% under all the simulated working conditions when the Eccentricity changed from 0 to 0.4. The proposed novel structure will facilitate the safety and conserve tube material, and the results can serve as a reference for the development of sCO2 power systems for industrial applications.

Supercooling behaviours of thermoelectric coolers with different continuous Double-pulse current waveforms

This study innovatively identifies techniques to improve the transient supercooling performance of thermoelectric coolers (TECs) through continuous double-pulse currents with different waveforms. Some applications need to operate at a specific temperature while obtaining the requirement for long periods of refrigeration, thus the new effective cold-holding time (teff-hold) for the defined effective cooling line and the variation curve of the cold-end temperature was used as the main index to measure the transient performance of the TEC. In addition, the cold-end minimum temperature (Tc,min), overshoot temperature (Tc,max), and the time for recovery to steady-state temperature (trec) of TEC were considered comprehensively. A three-dimensional (3D) multi-physics coupling transient model was constructed using numerical simulations, and its accuracy was verified by experimental data. Five typical pulse waveforms (-t−2, -t1/2, t0, t1/2, and t2) were used as the research objects. The results demonstrated that the waveform of the continuous double-pulse current plays an important role in improving the teff-hold of TECs under transient working conditions. In this simulation, the pulse widths (τ1 and τ2) of the first and second pulse currents were both 4 s when the pulse initial current was the optimal current (0.6A). When the pulse amplitudes (P1 and P2) were equal and small, the pulse current combination of t0 + t1/2 was applied, which could achieve relatively large teff-hold values. However, -t2 + t1/2 was more appropriate. Additionally, large teff-hold values for TECs could be achieved by reasonably choosing the pulse widths (τ1 and τ2) and amplitudes (P1 and P2) of continuous double-pulse waveforms and the initial current of the second pulse current (Iini,2). It is important to ensure that P1 is not too large, or it may lead to significant increases in Tc,min and Tc,max, a growth in trec, and a reduction in teff-hold. In this study, the optimal teff-hold was achieved (8.38 s) when the pulse current combination was -t2 + t1/2, P1 = 4, P2 = 3, τ1 = τ2 = 4 s, and Iini,2 = 0.55A.

Heterostructure design of 3D hydrangea-like Fe3O4/Fe7S8@C core-shell composite as a high-efficiency microwave absorber

In an era dominated by electronic equipment, the development of high-efficiency electromagnetic wave (EMW) absorbers is of great significance in solving the problem of electromagnetic (EM) pollution. Heterointerface engineering for optimizing EMW absorption performance depends on the design of vacancy, defect, and heterogeneous interface, which remains a considerable challenge in adjusting the micro and macro-interface effects. In this work, S atoms are incorporated into a dielectric-magnetic complementary system (Fe3O4/Fe7S8@C) to arouse the polarization effect of vacancies, defects, and non-uniform interfaces, thus tremendously boosting the EM energy attenuation capacity. Besides, the carbon shell provides more propagation paths for the dissipation of EMWs, and dielectric-magnetic synergy improves impedance matching. Eventually, in comparison with Fe2O3 and Fe3O4@C composites, interface-engineered Fe3O4/Fe7S8@C acquires a much better EM wave absorption performance. Its minimum reflection loss value reaches as much as −56.2 dB with a thickness of only 1.6 mm, and the corresponding effective absorption bandwidth (EAB) is up to 4.5 GHz. This unique hydrangea-like layered structure provides space to facilitate non-uniform coupling between the layers and has strong anisotropy to enhance the magnetic response. The high density of magnetic flux in the nanosheets builds a three-dimensional magnetic coupling network, which is supported by off-axis electron holography. Besides, the radar cross section from HFSS simulation further confirms that S-doping can favor the best synergy between dielectric and magnetic losses, facilitating the composite to achieve a more optimal impedance matching and improve the absorption capacity. In conclusion, this work presents new ideas for the design of excellent absorbing materials.

Experimental and numerical investigation on saturated concrete subjected to underwater contact explosion

The hydraulic concrete structures were partially or fully in direct contact with water during the service life. The mechanical properties of saturated concrete are different from dry concrete because of the presence of water. To investigate the underwater blast resistance mechanism of saturated concrete, saturated concrete slabs were first tested in underwater explosion experiments with different TNT masses of 2.5 g, 5 g, and 10 g. The experimental results showed that the crater on the front of the concrete slab was smaller than those on the back and the size of the crater increased with increasing mass of TNT. Numerical simulations were conducted and material parameters were determined based on additional tests: The damage model under different stress states was proposed by repeated loading and unloading tests in tension and compression under different confining pressures. The damage model was then embedded into the Holmquist-Johnson-Cook (HJC) model. Quasi-static and dynamic compression experiments were conducted to determine the material parameters of the saturated concrete. A three-dimensional fluid-solid coupling numerical model in ABAQUS was proposed for simulating the underwater explosion and its interaction with the saturated concrete slab. Finally, the mechanisms that produce differences in the damage pattern of concrete slabs at different explosive masses are revealed.

Crossover of critical behavior and nontrivial magnetism in the chiral soliton lattice host Cr1/3TaS2

The chiral magnetic soliton, a topological kinklike spin texture, has significant applications in spintronic components. In this work, a crossover of critical behavior is found in ${\mathrm{Cr}}_{1/3}{\mathrm{TaS}}_{2}$, a chiral magnetic soliton host with the highest ${T}_{C}$ to date. Angular-dependent magnetization reveals that ${\mathrm{Cr}}_{1/3}{\mathrm{TaS}}_{2}$ exhibits an easy orientation within the isotropic $ab$ plane, but displays anisotropy with the $c$ axis. By using a modified iterative method, two distinct sets of critical exponents, including ${\ensuremath{\beta}}_{\ensuremath{-}}=0.3190(1)$ and ${\ensuremath{\gamma}}_{\ensuremath{-}}=1.263(8)$ for $T\ensuremath{\le}{T}_{C}$, and ${\ensuremath{\beta}}_{+}=0.3475(2)$ and ${\ensuremath{\gamma}}_{+}=1.385(5)$ for $T\ensuremath{\ge}{T}_{C}$, are acquired on both sides of the transition. Analysis of the exponents indicates a crossover of the magnetic interaction from a three-dimensional Ising type below ${T}_{C}$ to a three-dimensional Heisenberg type above ${T}_{C}$, implying nontrivial magnetism in this system. Based on universality scaling, a detailed $H\ensuremath{-}T$ phase diagram around ${T}_{C}$ is constructed for $H\ensuremath{\perp}c$. The crossover of the critical behavior in ${\mathrm{Cr}}_{1/3}{\mathrm{TaS}}_{2}$ is peculiar to chiral magnetic soliton hosts, suggesting that the three-dimensional magnetic coupling is replaced by a one-dimensional one in the chiral magnetic soliton phase via a phase transition.

A three-dimensional ISPH-FVM coupling method for simulation of bubble rising in viscous stagnant liquid

The bubble rising problem has always been one of the research hotpots in the field of multiphase flow simulation due to the complex topological evolution of the phase interface. In this paper, an approach of coupling incompressible smoothed particle hydrodynamic (ISPH) and finite volume method (FVM) in three-dimensional space (abbreviated as 3D ISPH-FVM coupling method) is developed to simulate the bubble rising in viscous stagnant liquid. In the 3D ISPH-FVM coupling method, the coupling framework between the two numerical schemes is established through the information exchange at the overlapping regions. The effect of surface tension is evaluated by implementing the 3D continuum surface force model (CSF). To verify the interface capture accuracy of the 3D ISPH-FVM coupling method, several benchmark cases are tested. Then, the single bubble rising in viscous fluid is simulated by 3D ISPH-FVM coupling method, in which the results are compared with the experimental data and other numerical results in the literatures. To further explore the ability of 3D ISPH-FVM coupling method in bubble rising simulation, the effect of some parameters (including numerical and physical parameters) on single bubble rising is investigated. Afterwards, the dynamics phenomena of two bubbles coalescence are also studied. Numerical results validate the robustness and stability of the present coupling model in simulating the bubble rising.

Analysis of lead–bismuth eutectic-cooled solid reactor under flow blockage accident by 3D neutronics thermal-hydraulics coupling method

As the most common and serious accident in liquid metal-cooled reactors, the occurrence of a flow blockage accident may threaten the integrity of the cladding and the safety of the core. Therefore, the accurate prediction of fuel and cladding under blockage accidents is particularly important in reactor design and thermal–hydraulic analysis. This paper uses a three-dimensional neutronics thermal-hydraulics coupling method to analyze the blockage accident of a lead–bismuth-cooled solid reactor proposed by the Innovative Nuclear System Laboratory (INSL) of Shanghai Jiao Tong University. Based on the accurate and material models, the solid reactor was modeled, and 15 blockage accidents were carried out. The effects of the blockage's radial position, thickness and axial position on the fuel and cladding temperature were compared. Unlike the conventional open-channel blockage, the results of the closed-channel blockage accident analysis show that the thickness and axial position of the blockage has less influence on the maximum fuel and cladding temperatures but slightly affect the fuel and cladding axial temperature distribution. Meanwhile, the blockage accident in the closed channel is more serious, and the maximum temperature rise of fuel and cladding is higher, but both are lower than the limit value required by the design criteria.

Determination of the relative orientation between 15N-1H dipolar coupling and 1H chemical shift anisotropy tensors under fast MAS solid-state NMR

In this work, we have proposed a proton-detected three-dimensional (3D) 15N-1H dipolar coupling (DIP)/1H chemical shift anisotropy (CSA)/1H chemical shift (CS) correlation experiment to measure the relative orientation between the 15N-1H dipolar coupling and the 1H CSA tensors under fast magic angle spinning (MAS) solid-state NMR. In the 3D correlation experiment, the 15N-1H dipolar coupling and 1H CSA tensors are recoupled using our recently developed windowless C-symmetry-based C331-ROCSA (recoupling of chemical shift anisotropy) DIPSHIFT and C331-ROCSA pulse-based methods, respectively. The 2D 15N-1H DIP/1H CSA powder lineshapes extracted using the proposed 3D correlation method are shown to be sensitive to the sign and asymmetry of the 1H CSA tensor, a feature that allows the determination of the relative orientation between the two correlating tensors with improved accuracy. The experimental method developed in this study is demonstrated on a powdered U-15N L-Histidine.HCl·H2O sample.

Formation, evolution, and enhancement mechanisms of mixed temperature gradient during interfacial solar vapor generation

The solar evaporator, which generates a mixed temperature gradient (MTG) in the process of solar-driven interfacial water evaporation (SIWE), has shown great application potential in clean water production. It is also expected to provide a more comprehensive understanding to shed light on the formation, evolution, and enhancement mechanisms of the MTG. Herein, the space-time evolution of the solar absorber temperature and the evaporation performance in the column solar absorber are studied through a three-dimensional and multi-physical model coupling heat transfer and water transport. The results will demonstrate not only the temperature distribution during the SIWE process but the interface between positive temperature gradient (PTG) and negative temperature gradient (NTG). Moreover, the relationship between evaporation rate and light intensity, bulk water temperature, and environment humidity will be investigated. Importantly, the contributions of solar heating, PTG, NTG, and environment heating to the total evaporation rate will be quantitatively analyzed. Finally, based on the above results, the formation conditions, evolution characteristics, and enhancement mechanisms of MTG will be revealed. This paper will provide theoretical guidance for the successful construction and operation of an MTG evaporator for SIWE acceleration.

Architecture-inspired N-doped carbon nanotube bridging well-arranged MXene nanosheets toward efficient electromagnetic wave absorption

Multilayered Ti3C2Tx MXene, due to its tunable dielectric constants and structural designability, has been identified as rising star for exploring high-efficiency electromagnetic wave absorbers. However, it is still a huge challenge to address insufficient external contact of multilayered MXene at lower filler loading. Herein, inspired by the layer-pillar-layer architecture, a controllable catalytic-assisted nitrogen-doped carbon nanotubes bridging strategy is rationally proposed on the interlaminations of multilayered MXene units (MXene/TiO2/NCNTs, denoted as MTNC) to enhance dielectric dissipation ability. Through chemical vapor deposition, the NCNTs bridges as pillars not only break the confinement effect of multilayered MXene architecture like the process of seed germination but also effectively optimize impedance matching and increase dielectric constants. Simultaneously, the unique NCNTs-encapsulated magnetic components successfully prevents the agglomerations of CoNi nanoparticles and local mismatching problems, which facilitates the construction of three-dimensional magnetic coupling network. Specifically, the N heteroatoms and formed TiO2 species induce dielectric polarization and corresponding relaxation processes. Driven by unique layer-pillar-layer architecture, optimized impedance matching, and synergistic dielectric-magnetic dissipation capabilities, the resultant absorber delivers outstanding reflection loss value of −55.8 dB and broad absorption bandwidth of 5.88 GHz. This work provides a novel structural design strategy and enlightenment for developing high-performance multilayered MXene-based absorbers.

Evaluation of energy-saving potential and cabin thermal comfort for automobile CO2 heat pump

Currently, the heat pump air conditioning system is extensively used in Electric Vehicle (EV). However, most previous simulation studies focused on one-dimensional (1D) system performance rather than three-dimensional (3D) cabin thermal comfort. This study proposed a novel control strategy for the operation of a one- and three-dimensional coupling transcritical CO2 heat pump air conditioning system based on the weighted Predicted Mean Vote (PMV) model. The mathematical characterizations of the multiple thermodynamic systems were achieved by one-dimensional calculation and the cabin thermal environment was described by three-dimensional simulation. The weighted predicted mean vote value was calculated by real-time interactive three-dimensional cabin thermal environment parameters while providing control signals for the one-dimensional refrigeration system. The simulation comparison revealed the influence of the weighted Predicted Mean Vote control strategy on the system’s thermodynamic parameters and energy-saving potential. Results showed that the compressor power consumption of the Predicted Mean Vote control strategy was reduced by 9.1%-33.7%, compared with the method of presetting specific temperatures. The proposed one- and three-dimensional coupling method of cabin thermal management establishes the structured correlation between heat pump air conditioning system and cabin thermal environment. The weighted Predicted Mean Vote control strategy reduces the system power consumption within the thermal comfort range of the passengers, and it provides a novel idea for cabin thermal management during practical engineering.

Heat Transfer Performance Analysis of End Structures of Large Synchronous Condenser Based on Deep Forest Prediction Model

This paper presents a three-dimensional fluid-solid coupling heat transfer model of the end domain of a synchronous condenser. The temperature of the end structures and the flow distribution of the cooling medium were analysed. The highest temperature point of the structural part was explored, and the influence rule of the properties of the cooling medium on the temperature of the end structures of the condenser were analysed in detail. Based on the deep forest prediction model (DFPM), an accurate prediction of the temperature of the copper shield, far finger plates, clamping plate and stator end winding insulation was obtained by selecting a cooling medium and a heat-conducting medium with different properties. Comparing the predicted temperature data of the end structural parts with the finite element simulation results, the difference is minor. In addition, by measuring the temperature of the inner edge of the copper shield, the simulation results are in agreement with the measurement results, confirming the accuracy of the proposed model. The presented model can replace the complex simulation and can be considered an interesting reference for selecting the cooling scheme.

Three-dimensional coupling of electron cyclotron drift instability and ion–ion two stream instability

Electron cyclotron drift instability (ECDI) and ion–ion two stream instability (IITSI) are both kinetic instabilities that can be present in low-temperature, partially magnetized plasmas. The coupling of instabilities in a three-dimensional configuration leads to the existence of more than one unstable roots to the kinetic dispersion relation. In this paper, a generalized method has been developed for numerically evaluating solutions to the three-dimensional dispersion relation for coupled ECDI and IITSI, assuming cold singly and doubly charged ions and a Maxwellian velocity distribution function for the electrons. The present study demonstrates the coupling between ECDI and IITSI that affects the most unstable mode as a function of the wavenumbers in three dimensions and various plasma properties, including the applied electric field, magnetic field, electron temperature, ion velocities, and plasma density. One of the most notable results is that, while the most unstable mode with the largest growth rate is in the direction of the E×B drift in the two-dimensional cases, the most unstable mode for the three-dimensional configuration occurs in the oblique direction between the applied electric field and the E×B drift. This agrees with experimental observations in cross field plasma sources using coherent Thomson scattering.

Prediction of hydrodynamic noise in ducted propeller using flow field-acoustic field coupled simulation technique based on novel vortex sound theory

As one of the primary noise sources of underwater-robots, the hydrodynamic-noise of the ducted-propeller (DP) originates from various unsteady flows in the flow-field. To investigate the coupling-mechanism between the flow-field and the acoustic-field of DP, this paper establishes a three-dimensional flow field-acoustic field coupling numerical calculation model based on the vortex-acoustic equation. It combines simulation and experimental research to investigate the unsteady flow-field of the DP. The mechanism of acoustic-wave generation and the distribution characteristics of the acoustic field are studied, and the DP's propagation law of hydrodynamic-noise is analyzed based on the field-synergy theory. The results show that the DP domain's vortex structure is mainly influenced by the tensile-distortion and Coriolis-force term. However, hydrodynamic-noise generation is closely related to the vortex, turbulent pulsation, and other unstable flows in the flow-field. The radiated noise of the propeller decreases and then increases with the increase of the inlet velocity-coefficient (IVC) and is smallest at the optimal efficiency point (J = 0.6). With the increase of IVC, the synergy of the propeller flow field-acoustic field is enhanced, the energy-loss of acoustic transmission increases, and the far-field radiation noise decreases. This paper provides a theoretical reference for suppressing the hydrodynamic-noise of the DP and acoustic-optimization design of the underwater-robots.