Wire Spacing Research Articles

The electromagnetic field of a circular parallel plate capacitor excited by an AC current and AC voltage supply

Abstract This study investigates the electromagnetic field (EMF) distribution of an ideal circular parallel plate capacitor excited by a time-harmonic power source. Considering the lead wire and capacitor as a charged whole, we formulate the boundary value problems of the Helmholtz equation for the EMF in the lead wire space and capacitor space, respectively. First, we solve for the EMF generated by the total current in the lead wire space of an AC current. Following this, we solve for the EMF boundary value problem of a capacitor filled with linear, uniform, isotropic, and non-magnetic lossy dielectric under an AC current excitation, using the continuity of the total current as a basis. Second, the EMF distributions in the capacitor space and the lead wire space under an AC voltage excitation are provided, following the principles of the generalized Helmholtz theorem. Third, the EMF distribution is discussed when the electromagnetic ``standing-wave phenomenon" occurs in the ideal dielectric capacitor, and identify the ``resonance phenomenon" and the ``current-stopping phenomenon" of the capacitor's EMF when excited by an AC current and AC voltage, respectively. We also present the corresponding ``resonance frequency" and ``current-stopping frequency". Finally, we explore the quasi-stable solution of the capacitor's EMF under low-frequency condition and the static solutions of the electric and magnetic fields under DC excitation and static voltage excitation. Our findings suggest that the existing formula for the capacitor's EMF approximates our analytical solution under quasi-stable condition.

Design of dual-layer heater based on genetic algorithm to optimize magnetic field gradient in vapor cell

Addressing the constraint of magnetic field gradients in the vapor cell on enhancing the sensitivity of atomic magnetometers, this paper proposed a dual-layer heater design based on genetic algorithms, effectively reduced the magnetic field gradients within the vapor cell. The study analyzed the influence of key parameters of the resistive wire, such as wire width, thickness, and spacing, on magnetic noise generation in the three-dimensional model of the heater. The parameter combinations were then optimized synchronously using genetic algorithms to reduce the magnetic field gradient in the vapor cell region and enhance the magnetic noise self-suppression capability of the heater. The simulation results confirmed that the magnetic field strength in most areas remains below 40 pT, and the magnetic field gradient was well-managed. Additionally, further magnetic field experiments demonstrated that the heater's current-generated magnetic field had a strong self-suppression effect on magnetic noise, as evidenced by the index k value of -0.05. This paper provides convincing technical support and experimental evidence for improving the performance of the SERF atomic magnetometer.

Simulation Analysis Based on Sodium-Cooled Fast Reactor Fuel Assembly Under Blockage Accident

This paper employs computational fluid dynamics to investigate the fuel assemblies within a sodium-cooled fast neutron reactor. To begin with, we developed computational models for seven wire spacer fuel rods under both normal operating conditions and transient blockage conditions. We conducted separate analyses to assess the impacts of normal operation, blockage thickness, and blockage area. This work allowed us to acquire data on the heat transfer properties and the flow field variations for the coolant, blockages, and fuel rods across different conditions. Subsequently, we leveraged these flow field alterations to examine the resulting temperature distributions. Analyses were conducted to evaluate the effects of normal operation, blockage thickness, and blockage area. The research acquired the heat transfer characteristics and flow field distribution variations of the coolant, blockages, and fuel rods under different operational conditions and utilized these variations to analyze the temperature distribution. Through research analysis, the following conclusions have been reached. Under normal operating conditions, the temperature and flow fields of the fuel components exhibit cyclic variations along the axial length, corresponding to the pitch of the wire spacers. Heat exchange between the internal and external subchannels occurs independently, which further substantiates that the incorporation of wire spacers strengthens lateral flow disturbances. This effect is more pronounced within the internal subchannels, thereby leading to a marked difference in the flow fields on either side of the wire spacers. In the case of blocked conditions, an increase in blockage thickness and area both lead to higher temperatures for the coolant, the blockages themselves, and the fuel rods. The temperature in the recirculation zone behind the blockages also rises with increasing blockage thickness and area, although the magnitude of this increase is not significant. After the onset of blockage conditions, the instantaneous temperature tends to increase. As time progresses, the instantaneous temperature fields following the blockage do not display greater fluctuations in temperature change than those observed after the system has stabilized. For the temperature parameters of the convective field, differences arising from an increase in blockage area are more significant than those caused by an increase in blockage thickness. When blockage area and blockage thickness are increased by the same multiple, an increase in blockage area results in a higher temperature peak. Increasing the area of blockage necessitates a longer duration for both the temperature and the velocity fields to revert to equilibrium.

Comparative study on upward flame spread interactions and heat transfer over two parallel wires with various spacing distances in open space and vertical channel

Most previous work focused on the flame spread interactions and heat transfer over two parallel wires in open space, but few studies considered the vertical channel effects. Experiments were carried out to investigate the influence of vertical channel on the flame spread interactions and heat transfer over two parallel wires. Two types of polyethylene-insulated copper wires were used with spacing distance ranging from 0 mm to 52 mm. Whether for open space or vertical channel, four typical regimes of upward flame interactions are observed as a function of spacing distance, but the range of these regimes is affected by the vertical channel. For open space and vertical channel, the flame width, flame length and flame spread rate rise first and then drop, but these parameters for vertical channel are larger than that for open space due to the enhanced induced flow and the heat transfer. A heat transfer model is established for upward flame spread over two parallel wires taking the effects of spacing distance and vertical channel, in which the radiation from flame is considered, as well as the difference between the solid-phase and gas-phase heating lengths. The flame heat feedback is the dominant mechanism for upward flame spread over two parallel wires, and it for vertical channel is larger than that for open space.

Design of Inductive Power Transfer Charging System with Weak Coupling Coefficient

Inductive power transfer (IPT) technology is used in various applications owing to its safety features, robust environmental adaptability, and convenience. In some special applications, the charging pads are required to be as compact as possible to accommodate practical spatial requirements, and even size requirements dictate that the diameter of the charging pad matches the air gap. However, such requirements bring about a decrease in the transmission efficiency, power, and tolerance to misalignment of the system. In this paper, by comparing a double-sided inductor–capacitor–capacitor (LCC), double-sided inductor–capacitor–inductor (LCL), series–series (SS), and inductor–capacitor–capacitor–series (LCC-S) compensation topologies in IPT systems, we identified a double-sided LCC compensation topology that is suitable for weak coupling coefficients. Furthermore, this study modeled and simulated the typical parameters of coreless coils in circular power pads, such as the number of coil layers, turns, wire diameter, and wire spacing, to enhance the mutual inductance of the magnetic coupler during misalignment and long-distance transmission. A wireless charging system with 640 W output power was built, and the experimental results show that a maximum dc-dc efficiency of over 86% is achieved across a 200 mm air gap when the circular power pad with a diameter of 200 mm is well aligned. The experimental results show that using a suitable compensation topology and optimizing the charging pad parameters enables efficient IPT system operation when the coupling coefficient is 0.02.

Fabrication of Shape‐Controlled Copper Line Arrays by Meniscus‐Confined 3D Microprinting on Insulating Substrates

Meniscus‐confined electrodeposition (MCED), as a 3D printing process, exhibits excellent capabilities in microstructure fabrication. However, it faces numerous challenges, particularly when integrating with different substrates, especially insulating ones and cross‐layer interconnection. This study intends to investigate the impact of factors such as nozzle diameter, flight height of the nozzle over insulating substrates, and applied current by MCED on micro/nanoscale metal structures, to fabricate shape‐controllable and nanogap copper lines. As the flight height of the nozzle increases, there is no significant variation in the line height (≈60 nm) or width (≈15 nm) of the printed copper lines. And copper lines are successfully fabricated with consistent feature size oversteps totaling 1.2 μm in height. Additionally, highly dense copper line arrays are fabricated, achieving a minimum wire spacing of 120 nm. Remarkable stability and simplicity are realized in producing high‐resolution copper microstructures, demonstrating an acceptable degree of variability in insulating substrates and promising applications in integrated microsystems.

Simulation on lightning erosion protection performance of CFRP laminates with metal cluster structure

The tufting technology has the advantages of high flexibility and high economy. Research has found that metal tufting structures can significantly improve the mechanical and electrical properties of carbon fiber composites, and have great prospects in engineering applications. In order to investigate the damage characteristics of carbon fiber CFRP laminates with metal tufted structures during lightning strikes and the influence of structural parameters on lightning protection effectiveness, an electric thermal coupling model of CFRP laminates with metal tufted structures was established. Comparing the simulation and experimental results under the same load condition, it was found that the two were consistent in terms of damage appearance, damage area, and damage propagation trend, proving the effectiveness of the model. The transverse heat transfer process and current conduction path of CFRP laminates with metal cluster structure were discussed. The research results indicate that the ablation surface area of CFRP laminates with metal tufted structures is reduced to 8.06% of the reference component. Wire spacing had an effect on the area and shape of the area of the high potential region, and the wire spacing had the greatest impact on the ablation area of lightning strikes.

Method for fabricating a mesh ripple filter for charged-particle therapy

Objective. A simple, low-cost ripple filter consisting of multiple mesh sheets (mRiFi) was previously developed to reproducibly widen the Bragg peak of heavy-ion beams. To fabricate the mRiFi, the mRiFi parameters such as the wire material, wire diameter, wire spacing, and number of mesh sheets had to be determined. However, it was unclear how these parameters contribute to shifting and widening of the Bragg peak as well as to lateral spreading of the beam passing through the mRiFi. The purposes of this study were to clarify the contributions and to propose a recipe for fabricating a mRiFi with the desired performance values. Approach. We established an analytical calculation method to estimate shifting and widening of the Bragg peak and lateral spreading of heavy-ion beams passing through the mRiFi for given mRiFi parameter values. We also performed Monte Carlo simulations to validate the analytical calculation method. The recipe for fabricating the mRiFi with desired performances was established based on the analytical calculation method. Using the recipe, we fabricated the mRiFi for multi-ion therapy and evaluated its performance through demonstration experiments with helium-, carbon-, oxygen-, and neon-ion beams. Main results. The difference between the results of the Monte Carlo simulation and the analytical calculation was less than 0.4 mm for the peak shift, 0.15 mm for the peak width, and less than 0.11 mm for the lateral beam size which validated the analytical calculation method. The experimentally observed shift and width of the Bragg peak were consistent with the analytical calculations. Significance. We proposed a method to determine mRiFi parameters for fabricating a mRiFi with a desired performance, i.e. adequate widening of the Bragg peak with an acceptable peak shift and lateral beam spread. The proposed method allows anyone to fabricate a simple and low-cost mRiFi satisfying desired specifications.

Investigation of ultrasonic welding of CF/PA66 using nylon mesh energy directors

AbstractCarbon fiber reinforced polyamide 66 (CF/PA66) sheets are ultrasonically welded by applying nylon meshes as energy directors (EDs) in this paper. The influence of mesh dimensions is revealed by observing the joint formation process, joint mechanical performance, joint cross‐sectional morphology and joint failure mode. Results show that the joint formation process can be divided into wire flattening stage, ED spread stage, tight bonding stage, and mixing stage. The nylon mesh ED with moderate wire spacing, small wire diameter and small mesh area promotes better weld quality. Welding energy will be dispersed rather than concentrated if the mesh area is too large, resulting in reduced failure load. The joints exhibit two fracture modes: interfacial fracture (IF) and workpiece fracture (WF), and the fracture mode of the joints with nylon mesh EDs transits from IF to WF as the welding energy increases.Highlights Five types of nylon mesh are used as energy directors to join CF/PA66 sheets by ultrasonic welding. The influence of nylon mesh dimensions on the mechanical property and fracture mode of joints is investigated. The formation process of ultrasonically welded joints can be separated into wires flattening stage, ED spread stage, tight bonding stage, and mixing stage.

Role of various influencing parameters on high temperature fretting behaviour of different tribopairs in liquid lead

The increasing interest in liquid metal cooled nuclear reactors provides technical and scientific challenges such as the understanding, prevention, and prediction of the degradation of materials in liquid lead. Critical components include the fuel rods, heat exchanger tubes, and pump impellers. These functional elements are exposed to mechanical loading (up to 40 MPa), high temperatures (450–550 °C), and fluid-induced vibrations (up to 25 Hz). Under such conditions, fretting wear occurs between e.g., the spacer wire and the outer surface of the fuel or heat exchanger tubes. This work is aimed to establish a laboratory-scale fretting wear test setup and develop test methodology to enable systematic material characterisation in liquid metal environments. The results obtained by using the described methodology indicate that adhesive wear is the dominant degradation mechanism, and 316L stainless steel shows a higher coefficient of friction but a lower wear volume/tribolayer volume compared to 100Cr6 bearing steel. These results are in agreement with those reported in open literature and demonstrates the suitability of the presented method for conducting fretting tests and analysis for various materials and contact configurations in liquid lead environment.

Flow mixing and heat transfer deterioration investigation of supercritical carbon dioxide in wire-wrapped bundles

As one selection of the fourth-generation reactors, the gas cooled reactor has received enormous attention such as high power conversion efficiency and simple cycle layout. In this paper, the flow mixing and heat transfer characteristics of supercritical carbon dioxide within a seven-pin wire-wrapped bundle were investigated. Due to the lack of more experiments data of velocity field, two experiments were selected to validate the uncertainty of different turbulence models from the view of temperature field. The analysis of mass exchange between different subchannels revealed that coolant flows consistently in a certain direction in edge and corner subchannels, whereas in center subchannels, the cross flow changes direction periodically. The mixing coefficients at three types of subchannel interfaces were fitted by a sine function with the R2 values are all greater than 0.96. For different mass flux and pressures, the root mean square error between correlations and simulations was less than 1 × 10-3, except when Re equals 15000. Additionally, the heat transfer deterioration of SCO2 was observed. While wire spacers can mitigate the extent of heat transfer deterioration, they cannot completely eliminate it. The Performance Evaluation Criterion (PEC) was introduced to assess the effectiveness of wire spacers in enhancing heat transfer. The results indicate that the PEC exceed unity, meaning that the enhanced heat transfer capability outweighs the additional resistance loss caused by wire spacers. With increasing pressure, the PEC decreases but remains greater than unity. The mixing of coolant between different subchannel induced by wire spacers can reduce the wall temperature of rods at the edge of the bundle. However, the seven-pin wire-wrapped bundle was investigated in this work, and the results may not accurately reflect the flow and heat transfer inside a real reactor rod bundle. In the future, a larger scale rod bundle should be conducted to obtain more universally applicable and realistic flow and heat transfer phenomenon for reactor assembly design.

Electromagnetic characteristics analysis of dual-frequency magnetic single negative metamaterials

Abstract With the development of multi-frequency wireless transmission technology, it is necessary to expand the research of single-frequency metamaterials in the multi-frequency field. The dual-frequency metamaterial studied adopts a nested square spiral structure, which can resonate at two frequencies, and the real part of the equivalent permeability of metamaterial changes dramatically at the resonance frequency, and the equivalent electromagnetic parameter exhibits anomalous characteristics in the two frequency bands. Firstly, the effects of the number of turns, the width of the copper wire, the spacing of the copper wire, and the length of the outermost edge of inner and outer helical coils are investigated, respectively, using the HFSS software on the resonance frequency of dual-frequency metamaterials, which improves the study of dual-frequency metamaterials with nested square spiral structure. Then, based on the results of the change rule of resonance frequency with the four types of influencing factors, the dual-frequency metamaterials with the real part of the equivalent permeability close to -1 at 6.78 MHz and 13.56 MHz are designed, which is of certain reference significance for the subsequent practical design of dual-frequency metamaterials to satisfy the needs of the project.

Effects of confined distance and wire spacing on flame spread over double electrical wires for the layout design in buildings

In this study, the flame merging and flame spread behaviors over two identical parallel electrical wires (the ratios of copper core diameter to entire wire diameter are: 6mm/10 mm and 8mm/12 mm for typeⅠand typeⅡ, respectively) were experimentally investigated under different wire spacings (3∼18 mm) and confined distances(10∼30 mm). The results show that the smaller confined distance D will promote the merging, making the wire spacing s increase for the fully merging. With the increase of D, the flame width and flame spread rate Vf will increase.While the flame height will be stretched at smaller D. And Vf is larger than that of single wire at the same D for different wire spacings.The interesting finding is that a pool fire is formed at the middle of the wire spacing when s and D are small, which will enhance the flame spread.The heat flux feedback of components including of the conductive heat flux q˙c″, the first single flame heat flux q˙f1″, the second flame heat flux q˙f2″, the pool fire heat flux q˙pf″ and the gypsum board heat flux q˙g″ are quantitatively analyzed. At the intermittent and non merging stages, the convective and radiative heat fluxes q˙vf2″ and q˙rf2″ will decrease largely due to the interaction weakened greatly. Based on the heat transfer analysis, a flame spread model is established, which can well predict the flame spread rate.These findings can give the useful suggestions on the layout design of electrical wires in confined space in buildings.

A benchmark rapidly oscillating chemically peculiar (roAp) star: alpha Cir

The brightest chemically peculiar magnetic (mCP) star is also pulsating. Precise photometric and spectroscopic data, preferably with a long time base, are needed to investigate its evolutionary aspects as well. The present investigation of \ offers a space-based high-precision photometry study with high time resolution, covering 20+ years and supplemented by high resolution spectroscopy from the ground. We discuss the controversial rotation periods that have been recently reported and we consider new determinations of the actual values. We process the complex pulsation frequency spectrum, considering the implications in modelling the structure of We developed an automated Bayesian algorithm to consistently search for periodic signals in the WIRE, SMEI, TESS, and BRITE space photometric datasets, complemented by radial velocity data from HARPS. New observations in 2021 and 2023 from TESS and BRITE indicate a detection of as a triple system. The rotation period of has been determined as $4.4792890 The TESS data show a rich frequency spectrum including three $l=0$, six $l=1$, two $l=2,$ and one $l=3$ modes. Of these, five are shown to be rotationally split. The dipole modes show significant curvature in the echelle diagram, probably due to the strong magnetic field of Overall continues to be a cornerstone of mCP stars. A confirmation of the triple system requires additional space photometry and/or high-resolution spectroscopy to increase the time base. These data are also needed to improve the quality of the pulsation frequency spectrum and to investigate the evolutionary effects at play. A detailed seismic modelling study that considers the effects of a magnetic field on pulsation is subsequently recommended.

Influence of the Skin and Proximity Effects on the Thermal Field in Flat and Trefoil Three-Phase Systems with Round Conductors

The passage of current generates heat and increases the temperature of electrical components, which affects the environment, support insulators and contacts. Knowledge of the temperature allows for the determination of important operational parameters. Time-varying currents result in a nonuniform current density distribution due to the skin and proximity effects. As a result, temperature and energy losses are increased compared to the uniform DC current density case. In this paper, these effects are considered for three-phase systems with round conductors in flat and trefoil arrangements. In the first step, the analytical expressions for current distributions are determined and used to construct the heat source density. Then, a suitable Green’s function, which allows for obtaining temperature distribution in analytical form, is used to evaluate temperature at any point throughout the conductors. The temperature differences throughout individual wires are usually negligible, whereas noticeable differences can be observed between the wires. The impact of various parameters is examined, and an approximate closed formula is derived to assess the influence of the skin and proximity effects. When the skin depth is not smaller than the wire radius, the skin effect enlarges the temperature increase by around 2% compared to the DC case. As for the proximity effect, the additional increase can be neglected if the distance is above around 10 wire radii, but for closely spaced wires, it can reach up to around 17%, depending on the arrangement and the distance between the wires. Such an additional increase may result in exceeding the permissible temperatures, which damages particular components of the system; therefore, it is important to take it into account at the design stage.

Experimental investigation on damage mechanism of GFRP laminates embedded with/without steel wire mesh under low-velocity-impact and post-impact tensile loading

Abstract To investigate the impact behavior and residual strength of glass fiber-reinforced polymer (GFRP) laminates embedded with/without steel wire mesh, low-velocity-impact (LVI) and post-impact tensile tests are conducted carefully. According to the wire diameter and spacing of steel wire mesh, we manufactured two groups of specimens via conventional vacuum-assisted resin infusion. Further, the digital image correlation technique was applied to record the strain evolution. Based on the results, including impact response history, failure morphology, strain contour, the failure mechanism and effect of the parameters of steel wire mesh is revealed in detail. The results show that the embedding of wire mesh can improve the impact resistance and residual strength, with a more significant effect as both the increase of wire diameter and decrease of wire spacing. Compared with GFRP laminates, the peak force of specimens with the thickest and densest wire mesh increase by 105% and 141% under LVI tests and 254% and 141% in post-impact tensile tests, respectively.

A dynamic study of a bead sliding on a wire in fractal space with the non-perturbative technique

Drawing on the principles of fractal properties and nonlinear vibration analysis, this paper delves into the investigation of a moving bead on a vertically rotated parabola. The dynamical nonlinear equation of motion, incorporating fractal derivatives, transforms traditional derivatives within continuous space. Consequently, the equation of motion takes the form of the Duffing-Van der Pol oscillator. Utilizing a non-perturbative approach, the nonlinear oscillator is systematically transformed into a linear one, boasting an exact solution. The analytical solution yields two valid formulas governing the frequency-amplitude relationships. Numerical solutions affirm that these proposed formulas offer highly satisfactory approximations to the analytical solution. Leveraging fractal properties through Galerkin’s method, the paper successfully determines the fractalness parameter of the medium, shedding light on the intricate dynamics of the system.

Preparation of Oriented Superhydrophobic Surface to Reduce Agglomeration in Preparing Melt Marbles.

Numerous innovative granulation techniques utilizing the concept of liquid marbles have been proposed before. However, these processes frequently encounter issues such as collisions, aggregation, and fragmentation of liquid/melt marble during the granulation process. In this study, the oriented superhydrophobic surface (OSS) was successfully prepared by utilizing copper wire to solve the above problem, facilitating efficient batch production and guided transportation of uniform marbles. The parameters and mechanisms of this process were thoroughly studied. The optimized structure is that the copper wire spacing (d) and height (h) are set as 1.0 and 0.1 mm, respectively. This resulted in a surface contact angle (CA) of 156° and anisotropic sliding (ΔSA) of 16.3 ± 1.34°. Using the prepared substrate, high-quality urea products were successfully obtained through the controlled transport of urea melt marbles. The mechanism of guided and directional drag reduction, based on the solid/solid contact on the surface, is proposed. These findings in this study have significant implications for improving granulation processes.

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.