Wire Spacing Research Articles

Coupling effect between magnetic wires and its influence on high gradient magnetic separation performance

High gradient magnetic separation (HGMS) is effective for the separation of weakly magnetic minerals, and this method is achieved through the use of matrix, which is made of huge numbers of rod wires. So that the coupling effect of magnetic field and flow field between wires has a marked effect on the HGMS performance. In the investigation, the coupling effect between magnetic wires and its influence on high gradient magnetic separation performance were theoretically described and simulated using COMSOL Multiphysics. It is found that the magnetic field round a wire would be affected by the neighboring wires, and then a coupling effect of magnetic field between wires was produced, increasing the magnetic induction intensity on the upstream and downstream of wire surface. And the coupling effect of flow field could increase the slurry velocity at the regions of the wire surface with azimuth angles of 0° and 90°, which is beneficial for the selective capture of wire. These simulated results were basically validated with the experimental separation, using an innovative Magnetic Capture Analysis Method. It is found that the wire spacing has significant effect on the coupling effect of magnetic wires, and a critical spacing for wires could achieve an excellent coupling effect, which is beneficial for the improvement of HGMS performance. This investigation contributes to improve HGMS performance in concentrating fine weakly magnetic ores.

Numerical study of turbulent heat transfer of annular fuel assembly in a sodium-cooled fast reactor by a SST k-ω-kθ-εθ model

ABSTRACT The annular fuel has two cooling surfaces inside and outside, which can fully take away the heat of the fuel assemblies. It is urgent to conduct research on sodium-cooled fast reactor annular fuel assemblies. The Prandtl number Pr of liquid sodium is much less than 1 (Pr ˂˂ 1). The problem is that using the traditional constant turbulent Prandtl number Pr t of 0.85 ~ 0.9, which will greatly affect the accuracy of the numerical prediction of the thermal-hydraulic properties of liquid sodium. In order to address this issue, the turbulent heat transfer characteristics of the bare and wire spacers 7-pin annular fuel assembly for a sodium-cooled fast reactor are investigated by a SST k-ω-k θ -ε θ model. The open-source CFD software OpenFOAM is used for this calculation. In order to verify the validity of the present calculation method, some classical liquid metal heat transfer correlations are used to compare and analyze the results of the present calculation method (k θ -ε θ model), the results of the Reynolds analogy hypothesis (Pr t = 0.85 model), and the results of the turbulent Prandtl number correlation (Pr t = kays model). It is shown that the SST k-ω-Pr t = 0.85 model overestimates the Nusselt number Nu of the annular fuel assembly. The SST k-ω-k θ -ε θ model agrees well with the SST k-ω-Pr t = Kays model of the bare and wire spacers 7-pin annular fuel assembly . It suggests that the numerical calculation results of the SST k-ω-k θ -ε θ model are reliable in both the simple and complex fuel assembly models. In brief, the SST k-ω-k θ -ε θ model is more capable of predicting the turbulent heat transfer characteristics of the bare and wire spacers 7-pin annular fuel assembly in sodium-cooled fast reactors. In addition, the thermal-hydraulic characteristics of annular fuel assemblies with wire spacers for sodium-cooled fast reactors have been investigated. This research can provide a reference for the study of turbulent heat transfer characteristics of annular fuel assemblies in sodium-cooled fast reactor.

Research on Metal and Living Foreign Object Detection Method for Electric Vehicle Wireless Charging System

In the electric vehicle wireless power transmission system, the high-frequency alternating magnetic field between the transmitter and receiver can have a certain impact on the health of living organisms and may even lead to lesions. In addition, metal foreign objects in an alternating magnetic field can cause their own heating or even cause fires due to the eddy current effect, so foreign object detection is an essential function in the wireless power transmission system of electric vehicles. In order to prevent metals and living organisms from entering the charging area and causing harm to the charging system and living organisms, this paper proposes a method for detecting living organisms and metal foreign objects. Firstly, the equivalent circuits for the detection systems of the living organism foreign objects and metal foreign objects are established, respectively, and the working theory of the detection system is analyzed by deriving equations. Secondly, the comb capacitor simulation model was constructed, and the comb capacitor electrode spacing, wire thickness, and capacitor spacing were designed based on the scale factor γ to explore the effects of the height and bottom area of the living organism’s foreign object on the comb capacitor. We constructed a simulation model of the detection coil and designed the inner diameter D, the number of turns N, and the wire spacing S of the detection coil according to the scale factor β. An arrayed detection coil and comb capacitor combination mode is proposed to realize the function of the simultaneous detection of metal and living organism foreign objects, and a compensation capacitor is introduced to keep the detection system in a resonant state. Lastly, a platform for foreign object detection experiments was set up to detect metal screws and beef chunks compared to the detection area without foreign objects. Metal screws entering the detection area cause a 20% voltage drop in the detection circuit resistor, and beef chunks entering the detection area cause a 30% voltage drop in the detection circuit resistor, so the detection method is effective in detecting both metals and living organisms. The feasibility of the combined mode of arrayed detection coils and comb capacitors was verified.

Numerical heat transfer to LBE flow in a wire-wrapped 19-rod bundle using an OpenFOAM-based solver: fourParameterFoam

The LBE-cooled fast reactor (LFR) has received significant attention due to its diverse applications. However, numerical heat transfer simulations encounter challenges with lead-bismuth eutectic (LBE) due to its low Prandtl number and high molecular thermal diffusion, often resulting in an overestimation of heat transfer using the simple gradient diffusion hypothesis (SGDH). This study aims to improve the prediction accuracy of heat transfer to LBE in numerical models by developing a solver, named fourParameterFoam, based on the turbulent model SST k-ω and algebraic heat flux model (AHFM) kθ-ɛθ within the OpenFOAM framework. The performance of SGDH models and AHFMs is compared based on heat transfer experiments in vertical tube flow with LBE. The behavior of the turbulent Prandtl number (Prt) under various flow conditions is concluded based on the SST k-ω-kθ-ɛθ model. Additionally, the applicability of the SST k-ω-kθ-ɛθ model in complex flow is validated through heat transfer experiments in a wire-wrapped 19-rod bundle with LBE flow. Local temperature variations on the heated rod surface and sub-channels are analyzed to elucidate the thermal development process in the bundle. The impact of wire spacers on flow behavior is summarized using visualization techniques, and the suitability of corresponding empirical Nusselt number correlations in LBE flow is evaluated.

Non-linear oscillation of a mass attached to a stretched elastic wire in a fractal space

The challenge for a non-linear vibration system in a fractal space is more fractal dimensions than frequency-amplitude relationship, the system energy consumption depends upon its fractal property, so its best-case scenario is to establish a relationship among the fractal dimensions, frequency and amplitude. For this purpose, this paper studies a fractal-fractional vibration system of a mass attached to a stretched elastic wire in a fractal space, and its asymptotic periodic property is elucidated, the effect of the fractal dimensions on the vibration system is discussed. This paper offers a new road to fast and reliable analysis of fractal oscillators with high accuracy.

Hybrid de-icing method combining electrothermal system and ultrasonic guided waves

A novel hybrid de-icing method combining an electrothermal system and ultrasonic guided waves is proposed for the leading edge structure of wind turbine blades. The adhesion strength between the ice layer and the leading-edge structure is reduced by the electrothermal system. Piezoelectric ultrasonic transducers are used to generate shear stresses to crack and remove ice. The heating resistance wires and transducers are pasted onto the inner surface of the leading-edge structure. The spacing of the resistance wires was calculated by a theoretical thermal model. A temperature recorder was used to measure the temperature changes at different measuring points on the leading-edge surface under electric heating. This study conducted ultrasonic guided waves de-icing, electrothermal de-icing, and combined electrothermal–ultrasonic de-icing experiments in a freezer with an airfoil leading edge model. The results reveal that the combined electrothermal–ultrasonic method is feasible and has great potential for ice shedding acceleration.

Thermal-hydraulic analysis of LBE flow in rod bundles with wire spacers based on heat transfer framework of OpenFOAM

The wire spacer allows for a compact layout in the core of lead-cooled fast reactor (LFR). However, it also introduces complexity to the flow and heat transfer of the coolant, lead-bismuth eutectic (LBE). This paper aims to analyze the effect of wire spacer in rod bundle and the applicability of heat transfer framework to LBE flow. Three Reynolds-Averaged Navier–Stokes (RANS) turbulence models with two representative turbulent Prandtl number (Prt) 1.5 and 2.0 are employed within the framework of OpenFOAM. The sensitivity of the models is examined based on turbulent heat transfer in tube flow. The simulations considered with an extensive mesh sensitivity study were analyzed. The buoyantSimpleFoam solver is compared with direct numerical simulation (DNS) data. Thermal-hydraulic analysis are conducted, considering temperature, velocity distribution, and local Nusselt (Nu) number, and pressure drop based on 7-rod and 19-rod bundle with wire spacers. The influence of wire initial starting angles from 0°, 10°, 20°, 30°, 40°, 50° on heat transfer is carried out. The study reveals that an optimum angle range from 20° to 40° exists in the sub-channels. This work validates the basic heat transfer solver for LBE using OpenFOAM.

Investigating a method for macroscale energy extraction from random electrons movement

This paper aims to investigate a novel method for regularizing the random movements of electrons, in order to generate net movement and extract energy from the resulting electromotive force. The proposed method involves designing anisotropic conditions, focusing on exploring the effects of surface roughness on a metal wire in a two-dimensional space with the presence of a magnetic field. This paper presents a mathematical model for studying the proposed method. Furthermore, simulation results are analyzed and discussed in the context of the proposed method. By investigating the effects of surface roughness on electrons movement and voltage generation, this paper aims to contribute to the development of new methods for energy extraction from random electrons movement.

Direct Numerical Simulation of Heat Transfer in a 7-Pin Wire-Wrapped Rod Bundle

The Sodium-Cooled Fast Reactor (SFR) is a promising concept chosen in the Generation IV International Forum as a possible design for pursuing the sustainable use of nuclear energy. Its core consists of multiple hydraulically isolated assemblies, with a tightly packed triangular lattice array of fuel pins enclosed in a hexagonal duct present within each assembly. Helical wire spacers are wrapped along the axis of the rods to maintain a gap between them, inducing a secondary flow, increasing the channel mixing, and enhancing convective heat transfer. In this study, a direct numerical simulation campaign is conducted for a simplified 7-pin wire wrapper geometry, with Reynolds numbers ranging from Re = 1000 to 10 000 and a Prandtl number of Pr = 0.005, to investigate heat transfer in low-flow conditions. The wire wrapper case is compared to a bare bundle case with seven pins. The results are discussed, and heat transfer predictions are compared between our numerical results and classic correlations. An anisotropy invariant map is obtained for the above-mentioned cases, and turbulent kinetic energy and turbulent heat flux budgets are computed and analyzed. Our findings provide unique insights into the flow behavior within a wire-wrapped bundle.

Development of a clogging probability model in simplified geometry for fast reactor flow blockage analysis

The occurrence of flow blockage accident in fuel assemblies is considered as one of the primary challenges to be addressed in liquid metal fast reactors. Flow blockage accidents are primarily caused by the accumulation of solid particles, such as corrosion products, wire spacer fragments, and chemical products between liquid metal and impurities like air or water. To better understand the mechanisms underlying the blockage formation, a project consisting of several series of simulated experiments is currently underway at Sun Yat-sen University and Harbin Engineering University. In the initial stage of the project, experimental study was conducted to investigate the influence of particle characteristics on the probability of clogging by discharging various solid particles into a reducer pipe. Preliminary experimental analyses revealed the formation of an arch structure at a specific location on the pipe. This arch structure causes the granular flow to cease, resulting in blockage. Based on the accumulated experimental database, in this study an empirical model is developed to predict the clogging probability, taking into account the above-mentioned influential parameters. The model demonstrates a reasonable agreement with experimental results within the current range of conditions, encompassing variations in the ratio between hopper outlet size and particle size, particle capacity, particle static friction coefficient, and particle release height. Although further extension of the empirical model is inevitably necessary under more realistic reactor conditions, such as incorporating realistic sub-channels, irregularly shaped particles, or a loop with a liquid phase, it is expected that the model will be beneficial for the improved design of sub-channels and safety analysis of fast reactors.

Optimization of rotating coil system for magnetic center measurement and its application in high energy photon source

The Chinese high energy photon source is the fourth-generation light source that is currently under construction, with the booster being a significant component that has been completed by October 2022. In order to meet this timeline, 218 magnets requiring calibration were fitted with a rotating coil system and a three-coordinate measuring machine to optimize magnet center calibration. The rotating coil system is specially designed for magnetic center measurements. It employs a single-turn coil instead of the traditional complex compensated coil and uses a three-coordinate measuring machine imaging probe for precise positioning of the wire in space. This system has high accuracy, high speed, and high reliability. However, it is limited by the size of the three-coordinate measuring machine, meaning that larger magnets cannot be measured, thus limiting scalability. In September 2022, all of the magnets had been calibrated. This paper introduces the various aspects of coil design and examines the efficacy of employing three-coordinate measuring machine imaging for coil rotation center positioning and sag measurement, and provides a statistical analysis of calibration performance alongside mechanical calibration errors, the deviation between the magnet center and the mechanical center, and also a scatter analysis. Additionally, this paper also outlines the changes in the measuring time for each magnet, providing a reference for future magnet center calibration tasks.

Assessment of RANS and LES in predicting the flow in a 61-pin wire-wrapped bundle with a porous blockage

One of the most promising nuclear reactor designs is the Liquid-Metal Fast Reactor (LMFR). Its fuel bundle rods are separated with wire spacers that are helically wrapped around each fuel pin. Since this bundle presents a tight rod pitch to diameter ratio, accumulation of debris, cladding deformation or detachment of the wires may generate the formation of porous blockages. Understanding the coolant behavior in LMFR fuel bundles under the influence of blockages is mandatory for a complete nuclear safety evaluation. Therefore, this paper presents Computational Fluid Dynamics (CFD) results using the RANS k-ε Realizable and the LES models to simulate the flow of a 61-pin wire-wrapped bundle with the presence of a porous blockage that obstructed six interior subchannels. The simulated Reynolds numbers were 5,000 (transition regime) and 14,000 (turbulent regime). Results of the first and second order velocity statistics were compared with the Particle Image Velocimetry (PIV) experimental data acquired in the Thermal-Hydraulics Research Laboratory facility of Texas A&M University. The simulations results were found in reasonable agreement with the PIV data. Additional analysis of the flow structures, pressure distribution and power spectral densities were also performed to give more insight of the flow characteristics in LMFR reactors under the presence of porous blockages.

A Stream Function Smoothing Method for the Design of MRI Gradient Coils on Non-Developable Surfaces.

Insert gradient coils with similar imaging body shapes typically have smaller dimensions and higher spatial efficiency. This often allows the gradient coils the achievement of stronger and faster gradient fields. Thus, improving existing methods to make them applicable to the design of MRI gradient coils on complex surfaces has also become a challenge. This article proposes an algorithm that smooths the implicitly expressed stream function based on the intrinsic surface Laplace-Beltrami operator. This algorithm can be used to simplify the design procedure of MRI gradient coils on non-developable surfaces. The following steps are performed by the proposed algorithm: an initial design of the stream function configuration, extraction of the surface mesh, discretization of the surface smoothing operator, and a smoothing of the contour lines. To evaluate the quality of the smoothed streamline configuration, several technical parameter metrics-including magnetic field accuracy, coil power consumption, theoretical minimum wire spacing, and the maximum curvature of the contour lines-were evaluated. The proposed method was successfully validated in a design gradient coil on both developable and non-developable surfaces. All examples evolved from an initial value with a locally non-smooth and complex topological configuration to a smooth result while maintaining high magnetic field accuracy.

Numerical study of the impact of blockages on the Thermal-Hydraulic performance of 19 and 61-pin Wire-Wrapped bundles with conjugate heat transfer using RANS

Liquid metal fast reactors assemblies with wire spacers present a compact rod pitch to diameter ratio. Therefore, a typical off-normal condition that may occur is the blockage accident, caused by the accumulation of corrosion products or due to the detachment of broken wires. Blockage accidents may threaten the safety performance, leading to fuel rod damage. This work presents a thermal–hydraulic analysis using the RANS k-ε Realizable model to assess the impact of blockages. The model was validated on a blocked 19-pin wire-wrapped assembly comparing cladding and coolant temperatures and pressure drop with experimental data. Then, a numerical comparison between nominal and blocked conditions on a 61-pin wire-wrapped bundle was performed, analyzing solid and porous blockages. The greatest peak temperatures were obtained for the solid blockage case. Both types of blockages resulted in a similar velocity prediction upstream of the obstruction, while major differences were found in the recirculation region.

Performance evaluation of a novel electrostatic-vane compound demister using numerical simulation

A novel compound demister has been developed, incorporating an electrostatic field into the vane demister. This study aims to investigate the influence of various structural and operational parameters of the compound demister on droplet separation efficiency and pressure drop through numerical simulations. The results indicate that the compound demister, in comparison to the vane demister, significantly enhances the separation efficiency of fine droplets. At gas velocity of 6 m/s, the separation efficiency for 10 μm droplets reaches up to 90%, accompanied by a mere 46.8 Pa pressure drop. The separation efficiency demonstrates a negative correlation with vane spacing and electrode wire radius, while exhibiting a positive correlation with voltage and the number of electrode wires. However, the vane turning angle and the geometry of turning corner have a negligible effect on the separation efficiency. On the other hand, pressure drop increases with both increasing vane spacing and turning angle.

The effect of the corona wire distribution with W-type of collecting plates on the characteristics of electrostatic precipitators

Electrostatic precipitators (ESPs) are commonly applied to eliminate particles in various industrial sectors. A numerical study is conducted to evaluate the use of different arrangements of W-type collecting plates compared to flat plates (FPs) for a single stage of ESP. The modeling was done for six different ESP cases, and the W-type results obtained are compared to FPs to determine the consequence of corona wires spacing at different ratios of Lww/Lwp (Lww is a wire–wire space and Lwp is a wire–plate space) on the distribution especially of the electrical field, space charge density, and particle collection. The electric field close to the grounded collecting plates continued to rise when Lww/Lwp is reduced for both shapes. Furthermore, when compared to FPs, the use of W-types improves particle collection efficiency.

Combinatorial optimization of rotating matrix in centrifugal high gradient magnetic separation

Centrifugal high gradient magnetic separation (CHGMS) produces higher selectivity than conventional HGMS in concentrating weakly magnetic minerals owing to the use of rotating matrix, so its separation performance is closely related to the configuration of the matrix. In this work, the magnetic capture characteristics of the rotating matrices with different configurations to magnetic particles were described using a simulation model, and a combinative rotating matrix was proposed on the basis of the simulation results. The CHGMS performances of the combinative and conventional rotating matrices were then comparatively investigated for the separation of a fine ilmenite ore. From the simulation results, the increase in the spacing between magnetic wires and wire diameter decreases the mass weight of magnetic particles captured onto the internal wires of rotating matrix, improving its capture selectivity; whereas, the increase in the layer spacing of magnetic wires increases their capture mass weight, enhancing the capture capability of the matrix. For comparison, the combinative matrix achieves significantly superior performance to that of the conventional one for separating fine ilmenite, which is consistent with the simulation results. This investigation provides an important reference for the optimization and development of rotating matrix in CHGMS technology.

Simulation of low loss metamaterial based hollow core fiber for guiding mid-infrared (MIR) light

There is a great deal of interest in mid-infrared (MIR) light in diverse fields including spectroscopy, biomedical-applications, medical surgery, and astronomy. Due to higher material absorption, MIR light transmission is generally more difficult than visible light or microwave radiation. Recently, hollow-core MIR fibers are one of the best possibilities among presented several innovations having low Transverse Magnetic (TM) mode losses, although they are many orders of magnitude than Transverse Electric (TE) modes. Studies also have found that metamaterial-based HCF offers excellent potential for transmitting MIR light because of its distinct and flexible optical properties. In this study, a metamaterial-based HCF with an optimized design that uses metal wires with subwavelength spacing embedded in dielectric host, and acts as an effective TM reflector is proposed. In the 3 to 12 μm wavelengths, the effects of the design parameters including shape, number, and spacing of metal wires, dielectric thickness, and the diameter of the core are extensively investigated using finite element method. It is observed that TM01 mode losses are the lowest and a noteworthy confinement loss of 4.69× 10−7 dB/m is found at 9.5 μm wavelength, with an average loss of 5.22× 10−5 dB/m found within the range 8–10 μm wavelength. As the wires are wrapped up in a dielectric, there is a preferred position of 4 μm from the core edge and a number of 40 metal wires that results in the least amount of losses. This analysis could help to design low-loss metamaterial based HCF for guiding MIR light.

On the modification of wire wrapping process for fast Breeder reactor fuel Pins: Replacing hydraulic crimping with resistance spot welding

In this communication we report a modification in the conventional design of wire wrapping process for fast reactor fuel pins and related results. The fuel pins for sodium cooled fast reactors are wire wrapped helically along the length of the pin. In the conventional design of wire wrapping the end of the wire is mechanically crimped prior to Tungsten Inert Gas (TIG) spot welding with the end plug. In the modified design, we have incorporated resistance spot welding (RSW) of the wire with the plug in place of the hydraulic crimping operation prior to TIG spot welding. The quality of the welds were evaluated by metallography and tensile testing. Digital Image Correlation (DIC) studies were carried out for strain mapping during tensile testing. The modified design resulted in enduring ∼ 23% more load than the conventional design before fracture. The failure location during tensile pull test of spacer wire was observed at the resistance weld location. DIC studies during tensile testing showed that maximum strain was experienced by the resistance spot weld. Incorporation of modified design will ease the bottom end plug welding and wire wrapping process in addition to substantial cost reduction in fabrication of end plugs.

Investigation of ultrasonic welding of CF/PA66 using stainless steel mesh energy directors

This paper employs stainless steel mesh as energy director (ED) to join carbon fiber reinforced PA66 composite (CF/PA66). The effect of mesh size on the lap-shear failure load, cross-sectional microstructure, and fracture morphology is investigated. The results show that the mesh size has important impact on the weld formation and joint mechanical property. A small wire spacing leads to more pore defects in a joint; a large wire diameter increases the lack of fusion defects, and a large mesh area reduces the energy concentration effect. Mesh energy directors with large wire spacing, small wire diameter, and small area contribute to high joint strength. Under the appropriate welding energy and mesh size, the failure loads of joints are above 10000 N, and the failure model of these joints is workpiece fracture.