Multi-physical Field Coupling Research Articles

Investigation of the Dynamic Characteristics of a Two-Stage High-Speed On/Off Valve with Adjustable Maximum Opening

The effective way to improve the reliability of the fuel metering system in an aero-engine is to use a high-speed on/off valve (HSV) instead of a servo valve as the pilot stage of the fuel metering valve. However, the dynamic performance of the fuel metering valve is easily affected by the HSV, so a novel two-stage high-speed on/off valve with adjustable maximum opening (AMOHSV) is proposed in which the maximum stroke of the main valve is regulated with an adjustable rod. Firstly, the structure and working principle of the proposed valve are presented. Then, an entire mathematical model is established and verified based on a multi-physical field coupling mechanism. Finally, simulations and experiments prove that when the maximum opening is 0.2 mm, the total opening time and total closing time of the AMOHSV are within 5 ms. In addition, an upward inflection point and a downward inflection point on the pressure curve of the control chamber can be used to identify the total opening time and total closing time, respectively. The research results also prove that the proposed structure solves the conflict between the maximum flow rate and the dynamic performance of the traditional HSV.

Virtual wind tunnel modelling and numerical calculation of forklift power compartment based on acoustic-heat-flow multi-physical field coupling

Virtual wind tunnel modelling and numerical calculation of forklift power compartment based on acoustic-heat-flow multi-physical field coupling

Virtual wind tunnel modelling and numerical calculation of forklift power compartment based on acoustic-heat-flow multi-physical field coupling

Virtual wind tunnel modelling and numerical calculation of forklift power compartment based on acoustic-heat-flow multi-physical field coupling

Numerical Simulation of Contamination Accumulation Characteristics of Composite Insulators in Salt Fog Environment

To investigate the fouling characteristics of the composite insulator surface under the salt fog environment, the FXBW-110/120-2 composite insulator was taken as the research object. Based on the field-induced charge mechanism, the multi-physical field coupling software COMSOL was used to numerically simulate the fouling characteristics, explored the calculation method of ESDD, and demonstrated its rationality. Based on this method, the pollution characteristics of the composite insulator under the pollution fog environment were studied, and the influence of wind speed, droplet size, and voltage type on the pollution characteristics of the composite insulator was analyzed. The results showed that: with the increase in wind speed, the amount of accumulated pollution of insulator increases in the range of droplet size, and the relationship between wind speed and accumulated pollution is approximately linear; at the same wind speed, the amount of accumulated pollution increases with the increase of droplet size under the action of DC voltage; when there is no voltage, the amount of dirt on the upper surface of the insulator is more than that on the lower surface, while it is the opposite under DC voltage.

Melting Distribution of Armature in Electromagnetic Rail Launcher

This article established a 3-D transient melting calculation model of the electromagnetic rail launcher (EMRL), considering the combined effects of electromagnetic fields, structural fields, heat transfer, and armature motion. To verify the accuracy of the multiphysics field coupling model, an experiment platform of EMRL that is capable of retrieving the launched armature is set up. Compared with the armature surface profiles obtained from the experiment, the simulation model describes the locations of deeper melting accurately but is not precise enough for the shallower melting. Through analyzing the evolution of the melting region, it is found that the deepest crater forms at the point where the armature begins to melt. Analysis of the heat sources shows that contact resistance heat and body heat are two critical factors in the process of armature melting. Despite the high power of the frictional heat, there is no melting in the region where it exists. It is proven that the proposed model can predict the melting performance of the armature.

Rotor Design and Optimization of High-Speed Surface-Mounted Permanent Magnet Motor Based on the Multi-Physical Field Coupling Method

Rotor Design and Optimization of High-Speed Surface-Mounted Permanent Magnet Motor Based on the Multi-Physical Field Coupling Method

Magneto-stress-electric-coupled biosensors originated in magnetostrictive effect for sensitization

The stress-electric coupling based on receptor functionalization provides a new paradigm for biosensor development. However, it is difficult to avoid the gravity factor of the sensitive element since it can suppress biosensor sensitivity. Herein, a magnetic-sensitization sensing system based on multi-physical field coupling of stress, magnetism, and electricity is proposed to improve the sensitivity of surface stress biosensor. The gravitational interference of sensitive film is eliminated by the magnetostriction of TbDyFe under a magnetic field, amplifying the surface stress-induced film deformation. The urine protein and sugar detections associated with kidney disease serve as a proof of concept revealing the improved sensitivity. The calculated limits of detection (LODs) of urine protein and sugar are 0.21 ng/mL and 0.45 nM, respectively. The LODs are significantly lower than those of traditional surface stress biosensors without magnetic coupling, showing consistency with previous simulation and performance analysis. Furthermore, the urine protein and sugar in clinical samples are accurately detected, showing good practicability of the prepared biosensor. All these results indicate that magneto-stress-electric coupling in magnetostrictive effect contributes to the enhanced performance of surface stress biosensor and provides a platform for highly sensitive detection of clinical biomarkers.

The Identification Method of the Winding Vibration Faults of Dry-Type Transformers

To identify the four typical faults of dry-type transformer winding insulations, looseness, deformation and eccentricity, this study establishes the electric magnetic force multi-physical field simulation model of a dry-type transformer winding under the four typical faults with COMSOL software, based on the vibration mechanism of an SCB10-1000/10 dry-type transformer. Through the multi-physical field coupling calculation, the comparative relationship between the vibration acceleration of the winding under the four kinds of faults and the normal working state is obtained. The results show that the amplitude growth rate of the fundamental frequency or harmonic frequency of the acceleration signal under four kinds of faults is different from that under normal conditions. Therefore, the threshold value of the fundamental frequency or harmonic increment of the acceleration signal is introduced to describe the growth rate of the acceleration signal relative to normal conditions. Finally, four typical faults are identified with different threshold ranges of acceleration increment under faults, laying a foundation for the fault diagnosis of transformer winding vibrations.

Numerical study on power battery thermal management system based on heat pipe technology

In the present work, a power battery pack and a novel thermal management system (TMS) based on the tubular heat pipe (THP) technology are designed according to the parameters of a pure electric light truck and battery. The TMS consists of THPs, power batteries, cooling plates, fins, and equivalent thermal conductivity is used to characterize the excellent thermal conductivity of THP. The heat generation rate of the battery at different discharge rates is obtained by establishing a multi-scale electrochemical–thermal coupling model, which accuracy is verified by the experiment. A multi-physics field coupling model is built to the thermal management system designed for the study. The results show that the battery temperature is higher when the battery is far from the THP in the cooling plate, and the maximum temperature reaches 35.6 °C at 1 C. Furthermore, the temperature difference between batteries is proportional to the discharge rate, and the maximum temperature difference reaches 7 °C at 2 C. The change in inlet temperature and wind speed can only restrain the temperature rise, while the temperature difference of the battery module is always 3.2 °C. When a fin spacing of 3 mm is chosen, the best temperature uniformity of the battery module is achieved at this time. The use of the multi-scale multi-physics field coupling analysis method in BTMS with heat pipes can be used as a reference for future numerical simulations of the same type.

Effects of corrosion defect growth on submarine pipeline under operating pressure and axial displacement

Corrosion defect growth with time seriously threatens the safe operation of submarine pipelines and the study about its effects on strength degradation is essential for pipeline integrity assessment. In this work, a three-dimensional finite element model was developed to simulate the defect growth on pipeline exposed to sea mud environment based on multiphysical field coupling and deformed geometry. The deeper defect and larger operating pressure (OP) enhance local stress concentration and corrosion rate. The corrosion rate decreases first and then increases with the axial displacement (AD) of pipeline. The OP causes pipelines to corrode preferentially on the defect bottom while AD trends to form uniform corrosion on the total defect surface. There is an anti-synergistic effect between OP and AD on pipe thinning. A residual service life estimation method based on the unsteady multi physical field simulation was proposed for the submarine pipeline.

Effect of curing pressure on the stability of bottom cemented paste backfill under different types of barricade

In this paper, a multi-physical field coupling curing experimental instrument was developed to study the effect of curing pressure on the stability of bottom cemented paste backfill (CPB) under two different barricades. The effect mechanism was analyzed by using 5TE, MPS-6 sensor, scanning electron microscope (SEM), and binary processing of SEM images. And then, the strength prediction model of CPB under different curing conditions was established. The findings show that the strength of CPB increases with curing pressure regardless of permeable or impermeable barricade, and the relationship between CPB strength and curing pressure conforms to the law of linear function, and the change law of strength grow rate can also be expressed by a linear function. The curing pressure will accelerate the hydration reaction rate and compress the internal pores of the CPB, making the structure of the CPB more denser, thus promoting the formation of strength. It is worth noting that after the curing pressure was increased to 600 kPa, the strength growth rate of CPB slowed down in the later period, and obvious cracks appeared in the bottom CPB during sampling. The results will be helpful to better consider setting different types of barricade at different stope heights

Digital twin-oriented multi-physics field simulation analysis of high-voltage SF6 circuit breakers

Circuit breakers are important components for removing short circuits in power systems and ensuring safe operation. The operation of circuit breakers may not be predicted and thus cause accidents, so there is an urgent need to innovate means to assess the operation status of power equipment and monitor the operation status of power grids in full real time, to improve the monitoring capability of major key equipment, and to study key technologies for the digital twin of circuit breakers to support the safe and stable operation of transmission networks and the digital transformation of energy systems. This paper establishes the multi-physics field coupling calculation model of the circuit breaker opening process, completes the simulation calculation of the circuit breaker opening process, gets the distribution and change trend of parameters such as electric field, pressure, temperature, density, and airflow speed inside the interrupting chamber, and analyzes the flow characteristics inside the interrupting chamber in different opening processes. We select the characteristic parameters and provide data support for the establishment of fault diagnosis based on the digital twin of the circuit breaker.

Investigation and Application of Magnetic Properties of Ultra-Thin Grain-Oriented Silicon Steel Sheets under Multi-Physical Field Coupling

Nowadays, energy shortages and environmental pollution have received a lot of attention, which makes the electrification of transportation systems an inevitable trend. As the core part of an electrical driving system, the electrical machine faces the extreme challenge of keeping high power density and high efficiency output under complex workin g conditions. The development and research of new soft magnetic materials has an important impact to solve the current bottleneck problems of electrical machines. In this paper, the variation trend of magnetic properties of ultra-thin grain-oriented silicon steel electrical steel (GOES) under thermal-mechanical-electric-magnetic fields is studied, and the possibility of its application in motors is explored. The magnetic properties of grain-oriented silicon steel samples under different conditions were measured by the Epstein frame method and self-built multi-physical field device. It is verified that the magnetic properties of grain-oriented silicon steel selected within 30° magnetization deviation angle are better than non-grain-oriented silicon steel. The magnetic properties of the same ultra-thin grain-oriented silicon steel as ordinary non-oriented silicon steel deteriorate with the increase in frequency. Different from conventional non-grain-oriented silicon steel, its magnetic properties will deteriorate with the increase in temperature. Under the stress of 30 Mpa, the magnetic properties of the grain-oriented silicon steel are the best; under the coupling of multiple physical fields, the change trend of magnetic properties of grain-oriented silicon steel is similar to that of single physical field, but the specific quantitative values are different. Furthermore, the application of grain-oriented silicon steel in interior permanent magnet synchronous motor (IPM) for electric vehicles is explored. Through a precise oriented silicon steel motor model, it is proved that the magnetic flux density of stator teeth increases by 2.2%, the electromagnetic torque of motor increases by 2.18%, and the peak efficiency increases by 1% after using grain-oriented silicon steel. In this paper, through the investigation of the characteristics of grain-oriented silicon steel, it is preliminarily verified that grain-oriented silicon steel has a great application prospect in the drive motor (IPM) of electric vehicles, and it is an effective means to break the bottleneck of current motor design.

Study of High-Silicon Steel as Interior Rotor for High-Speed Motor Considering the Influence of Multi-Physical Field Coupling and Slotting Process

Currently, high-speed motors usually adopt rotor structures with surface-mounted permanent magnets, but their sheaths will deteriorate performance significantly. The motor with interior rotor structure has the advantages of high power density and efficiency. At the same time, high silicon steel has low loss and high mechanical strength, which is extremely suitable for high-speed motor rotor core material. Therefore, in this paper, the feasibility of using high silicon steel as the material of an interior rotor high-speed motor is investigated. Firstly, the magnetic properties of high silicon steel under multi-physical fields were tested and analyzed in comparison with conventional silicon steel. Meanwhile, an interior rotor structure of high-speed motor using high silicon steel as the rotor core is proposed, and its electromagnetic, mechanical, and thermal properties are simulated and evaluated. Then, the experimental comparative analysis was carried out in terms of the slotting process of the core, and the machining of the high silicon steel rotor core was successfully completed. Finally, the feasibility of the research idea was verified by the above theoretical analysis and experimental characterization.

Design and Performance Analysis of a Double-Outlet-Rod Magnetorheological Damper for Impact Load

In order to improve the performance of magnetorheological dampers under impact load, a double-rod magnetorheological damper is designed in this paper, and its multi-physical field coupling model is established. The performance of a double-rod magnetorheological damper under impact conditions is characterized from the aspects of viscosity, velocity, peak pressure, impact energy consumption and viscous damping force ratio. The research contents include: a comparison of dynamic characteristics such as the viscosity, velocity and pressure of the magnetorheological damper under impact conditions and low-speed vibration; the influence of temperature on the mechanical performance parameters of the magnetorheological damper, such as peak pressure, impact energy dissipation and viscous damping force ratio, under impact load; and the establishment of a peak sensitivity function to study the influence of three key structural parameters on the magnetic flux density and impact energy dissipation at the damper damping channel. On the basis of the above theoretical research, an impact test of the processed double-rod magnetorheological damper prototype under different excitation currents is carried out. The results show that the viscosity distribution of the damping channel activation region (i.e., the region where the magnetorheological effect occurs after energization) of the magnetorheological damper under impact is disordered, the region of the structural flow in the semi-solid state is small and the influence of the Coulomb damping force is greatly weakened. When the current is 0.5 A, the viscous damping force accounts for 91.2%, and the viscous damping force plays a major role in buffering energy absorption. With an increase in working temperature, the effect of the Coulomb damping force decreases, and the peak pressure and impact energy consumption of the MR damper decrease greatly. With increasing excitation current, this reduction is further increased. The influence of gap height, piston diameter and effective length on magnetic flux density and impact energy dissipation is determined via the peak sensitivity function. When the change in the structural parameters ∆α is 30%, the change in the piston diameter has the greatest influence on the peak sensitivity of the magnetic flux density, and the peak sensitivity index of the magnetic flux density reaches 25%. The change in clearance height has the greatest influence on the impact energy consumption, and the peak sensitivity index of the impact energy consumption reaches 115%. This shows that the magnetic flux density is most affected by the piston diameter, and the impact energy consumption is most affected by the clearance height. The test results show that the test pressure peak-change curve is consistent with the simulation pressure peak-change curve, and the pressure peak error between the two is within 10%.

The Simulation Analysis of IGBT Module Based on COMSOL

IGBT, as the core device of high-capacity power electronic equipment, its stability is directly relevant to the normal operation of the equipment. It would cause system failure and major security incidents if aging failure phenomenon occurs. A complex multi-physical field coupling process is involved in the aging failure of IGBT. Based on Comsol software, this paper conducts a series of simulations on IGBT module model SKM50GB12T4, and also improves the simulation of the solder layer voids by combining with related literature on materials science to provide a basis for subsequent research on IGBT.

Finite element simulations of corrosion defect with different inclination angles in submarine pipelines using multi-physics field coupling and deformation geometry

Fitness for service assessment of corrosion defects is very important for the safe operation of submarine pipelines. A three-dimensional model was built to analyze the corrosion defect on the outside surface of the pipeline which was influenced by mechano-electrochemical (M-E) effect. M-E effect has the greatest impact on the 0° corrosion defects which decreases with the angle increasing from 0° to 90°. The stress and corrosion rate of corrosion defect significantly rise with the increase of defect's initial corrosion depth, especially in the center. The initial corrosion depth and corrosion defect angle have an obvious synergistic effect. Thus, it should be paid more attention when the angle of the defect is 0° for pipeline integrity management. In addition, the angle of corrosion defect and axial tensile displacement have an antagonistic effect. A synergistic effect exists between the angle of the corrosion defect and the pipe's internal pressure.

Material design and temperature field simulation analysis of tumor radiofrequency ablation needle

To solve the problems of small one-time ablation range and easy charring of the tissue around the electrode associated with the tumor radiofrequency ablation needle, based on the multiphysical field coupling analysis software COMSOL, the effects of needle material, the number of sub needles and the bending angle of sub needles on the ablation effect of radiofrequency ablation electrode needle were studied. The results show that compared with titanium alloy and stainless steel, nickel titanium alloy has better radiofrequency energy transmission efficiency and it is the best material for electrode needle. The number of sub needles has a great influence on the average necrosis depth and the maximum necrosis diameter. Under the same conditions, the more the number of sub needles, the larger the volume of coagulation necrosis area. The bending angle of the needle has a great effect on the maximum diameter of the coagulated necrotic area, but has little effect on the average necrotic depth. Under the same other conditions, the coagulation necrosis area formed by ablation increased with the increase of the bending angle of the sub needle. For the three needles with bending angles of 60 °, 90 ° and 120 ° analyzed in this paper, the one with bending angle of 120 ° can obtain the largest coagulation necrosis area. In general, the design of nickel titanium alloy with 120 ° bending 8-pin is the optimal. The average depth of radiofrequency ablation necrosis area is 32.40 mm, and the maximum necrosis diameter is 52.65 mm. The above optimized design parameters can provide guidance for the structure and material design of tumor radiofrequency ablation needle.

The electrodynamics of rod-like microparticles based on optically induced dielectrophoresis.

Due to its characteristics of noncontact, non-damage, high flux, and easy-to-achieve flexible manipulation, optically induced dielectrophoresis (ODEP) technology has been employed to manipulate microspherical biological particles, including separation, enrichment, capture, arrangement, and fusion. However, in nature, biomolecules are morphologically diverse, and some of them are rodlike. In order to illustrate the electrodynamics of rodlike particles under the action of ODEP, a transient multi-physical field coupling model of ODEP chip under the hypothesis of electrical double layer thin layer was established in this paper. The arbitrary Lagrangian-Eulerian method is used to track single-rod particle in the strong coupled flow field and electric field simultaneously. The influence of several key factors, including the applied alternating current (AC) electric voltage, the width of optical bright area, and the initial position of particle, on the trajectory of particle center was analyzed in positive dielectrophoresis (DEP) action and negative DEP action, respectively. Especially, the planar motion process of rodlike particles was discussed together. The research results reveal the electrodynamics behavior of rodlike particles based on the action of ODEP, which may provide theoretical support for the further design of rodlike biological cells manipulation chip based on AC ODEP technology in the future.

Research on Multi-physics Field Coupling Dynamic Process in Forward Flow Electrochemical Trepanning Blades

In this work, a multi-physics field coupling model based on electric field, gas-liquid two-phase flow field and temperature field of the forward flow electrochemical trepanning (FFECT) blades was established, and the distribution law of hydrogen bubble volume fraction, electrolyte temperature and electrolyte conductivity in machining gap was obtained. Based on the simulation results, the time-varying process of electrolyte flow velocity distribution was divided into three stages according to the change in machining gap corresponding to different blade machining heights H, and the effects of the machining voltage U and the cathode feed rate v on the side gap Δ s and the end gap Δ e were investigated. The simulation analysis and experimental results show that both side gap and end gap increase as machining voltage increases while decrease with the increase in cathode feed rate. The model predictions are in good agreement with the experimental results, and the maximum errors of side gap and end gap are 10.6% and 17.7% respectively. In addition, the effects of machining voltage and cathode feed rate on the surface quality were studied experimentally. Results reveal that surface roughness can be reduced by appropriately decreasing the machining voltage and increasing the cathode feed rate.