Three-dimensional Core Research Articles

Effect of CO2-assisted surfactant/polymer flooding on enhanced oil recovery and its mechanism

D oilfield is a typical heavy oil reservoir affected by bottom water and has the characteristics of high porosity, high permeability, and strong heterogeneity. However, water flooding leaves oil behind due to unfavorable mobility ratios and capillary forces. The layer (well section) with poor or no liquid entry ability originally has been improved in the process of surfactant/polymer flood. However, fluid entry distribution interlayers were not improved obviously in the middle and late stages. To further improve the recovery efficiency of surfactant/polymer flooding on bottom water reservoirs, the CO2-assisted surfactant/polymer flooding development method had been proposed. The optimal composition of the surfactant/polymer system was selected by evaluating the oil-water interfacial tension and viscosity. Three-dimensional cores with bottom water were used in CO2-assisted surfactant/polymer flooding experiments to improve oil recovery. On this foundation, the screening of oil displacement agents, optimization of oil production well location, and injection pressure were carried out. Based on the comprehensive analysis of the produced liquid, the CO2 assisted surfactant/polymer flooding to enhanced oil recovery mechanism was analyzed. The results showed that the surfactant named BS had a low oil-water interfacial tension of 3.79 × 10-3 mN/m. In addition, salinity decreases the viscosity of the surfactant/polymer solution. It was found that conducting CO2 huff and puff after chemical flooding can improve oil recovery. Among the four chemical agents, CO2-assisted the anionic nonionic surfactant and the salt-resistant polymer system flooding had the highest recovery. Moreover, the location of the oil production well, that is, the distance between it and the bottom water layer, has an impact on the recovery. During the experiment, 2.5 cm was the farthest distance between the oil production well and the bottom water layer, at which point the recovery was highest at 70.9%, and the bottom water breakthrough rate was 2.4%. These results provide theoretical and technical support for the development of CO2-assisted surfactant/polymer flooding and its application in wells.

Enhancing performance of sandwich panel with three-dimensional orthogonal accordion cores

This study introduces a novel three-dimensional orthogonal accordion structure (3D-OAS) as the cellular core of sandwich panels, achieving multi-directional zero Poisson’s ratio through the orthogonal combination of two-dimensional accordion structures. To analyze its static characteristics effectively, a two-dimensional equivalent Reissner–Mindlin model (2D-ERM) was established utilizing the variational asymptotic method (VAM). The accuracy of 2D-ERM was confirmed by conducting three-point bending tests on 3D-printed specimens and analyzing the in-plane and out-of-plane deformation results of the 3D finite element model (3D-FEM). The comparison of global displacement contours and path-displacement curves between 3D-FEM and 2D-ERM showed a high level of agreement in predicting static deformation. The equivalent stiffness of SP-3D-OAS steadily increased as the inclined angle deviates by 90-degree, irrespective of whether it pertains to the convex or concave angle. Evaluation of deformability in sandwich panels with different cellular core forms revealed superior comprehensive performance in 3D-OAS, followed by 3D-YRS and 3D-XYAS, with a reduction of 16.41% and 17.35% in specific stiffness, respectively. Compared to the 3D-FEM, 2D-ERM significantly reduces computation time without compromising engineering accuracy. The research results provide a useful reference for optimal design of sandwich panels with multi-directional ZPR cellular core.

Development and testing of hybrid (PNM–CFD) mathematical model and numerical algorithm for description of fluid flows in three-dimensional digital core models

Numerical simulation of fluid flow in porous and fractured rocks is an important task for many industrial applications. The most common approaches to constructing such models are direct (CFD or lattice Boltzmann) and porous network (PNM) modeling. Each approach has its own advantages and disadvantages. This paper presents a hybrid mathematical PNM–CFD model for describing fluid flows in three-dimensional digital core models, which has the high speed performance of PNM approaches and high accuracy of CFD models. Numerical technique has been developed for describing fluid flows in three-dimensional digital core models using a hybrid PNM–CFD model. The numerical technique links a one-dimensional pore network solver and a three-dimensional CFD solver into a combined model in original way by constructing a single pressure field for the entire computation domain. To validate the model, several tests were performed, including flow in straight channels and numerical simulation of fluid flow in a microfluidic chip. The test results have shown the adequacy of the hybrid model performance. The hybrid model for determining pressure drop in a branched network with three-dimensional chambers has an error of no more than 5 % when compared to experimental data. Similarly, the error in calculating velocity does not exceed 7 % when compared to the full three-dimensional calculation. The hybrid model has shown an almost twofold increase in calculation speed compared to the full three-dimensional model.

Free vibration analysis and multi-objective robust optimization of three-dimensional pyramidal truss core sandwich plates with interval uncertain parameters

In this study, the free vibration analysis and multi-objective robust optimization of three-dimensional pyramidal truss core sandwich plates with interval uncertain parameters are fulfilled. The numerical model for free vibration of the plate is derived by combining the three-dimensional elasticity theory and Rayleigh-Ritz method, and the validity of the model is illustrated by numerical results. On this basis, considering various uncertainties within the plate, a new uncertainty-propagation analysis method is constructed by integrating the numerical model, interval-analysis model, kriging model and optimization. The one-dimensional and multi-source uncertainty-propagation analysis of the fundamental frequency is finished using this method, and the accuracy is proved by comparing with Monte Carlo simulation results. Meanwhile, to minimize the effects of uncertainties on the performance of plates at the design stage, an objective multi-objective robust optimization model with the objectives of maximizing the fundamental frequency and minimizing the robustness factor is established. Finally, an improved pelican optimization algorithm is proposed by introducing the improved opposition-based learning strategy, tracking strategy with step control and convergence strategy. And the Pareto front and corresponding design schemes applicable to different working environments are obtained without repeating the optimization.

Verification of Adjoint Solution Commutativity with the New OpenNode Nodal Diffusion Code

This paper presents in-depth exploration and verification of the OpenNode nodal diffusion code, a robust tool designed for multigroup neutron diffusion simulations under steady-state conditions. Leveraging the Nodal Expansion Method with a quartic polynomial and moments weighting method, OpenNode demonstrates exceptional accuracy in approximating nodal surface fluxes, further enhanced by the Quadratic Transverse Leakage approximation. The critical concept of commutativity between adjoint and forward solutions is thoroughly investigated, serving as a benchmark for the code’s reliability in predicting system responses, determining single-point reactor kinetics parameters, and facilitating perturbation analyses. The paper meticulously details OpenNode’s methodology for adjoint neutron flux computation, unraveling its rigorous approach through transposition operations and intricate mathematical transformations. Noteworthy features, including support for second and fourth polynomial orders; versatile computation modes; different mesh points; and seamless integration with Python, PyQt5, and Blender, underscore OpenNode’s adaptability. Results from comprehensive analysis of the two-dimensional and three-dimensional International Atomic Energy Agency core benchmark problem showcase OpenNode’s prowess. The code excels in reactor geometry visualizations, benchmark parameters, and neutronic analysis, with a particular emphasis on commutativity verification against various benchmarked codes. The precision of OpenNode is further demonstrated in power distribution analyses, revealing remarkable proximity to reference values and symmetrical power distribution patterns.

Multi-factor numerical simulation and response characteristics of two-dimensional nuclear magnetic resonance in digital cores

Two-dimensional nuclear magnetic resonance (2D NMR) logging is an important technology for reservoir evaluation in oil and gas exploration and development, and it has unique advantages in fluid identification. However, in oil shale reservoirs, the mechanisms of 2D NMR logging are complex, and the response characteristics of various factors are unclear. Numerical simulation based on digital core is a significant method to study the influences of multiple factors on 2D NMR. This manuscript introduces the construction method of high-resolution three-dimensional (3D) digital core models, and expounds the principle and workflow of 2D NMR numerical simulation. High-resolution 3D digital cores were constructed based on X-CT, MAPS, and QEMSCAN data of Berea sandstone and Daqing Gulong shale, respectively. Based on 3D digital cores, 2D NMR numerical simulations were carried out on temperature/viscosity, echo spacing, and frequency. Then, 2D NMR mechanisms were analyzed and the response characteristics of multiple factors were summarized. The results show that the T2 and T1 of the water peak have a linear negative correlation with temperature/viscosity, and the T2 and T1 of the oil peak have a linear positive correlation. For Daqing Gulong shale, the T2 of the water peak has a linear positive correlation with echo spacing, while for Berea sandstone, echo spacing has little effect. For Berea sandstone, the T1 of the water peak is linearly positively correlated with frequency. For Daqing Gulong shale, the T1 of the water peak and oil peak are both linearly positively correlated with frequency. The response characteristics of multiple factors could provide a reference and basis for the interpretation and evaluation of 2D NMR logging under complex conditions.

Simulation of nuclear magnetic resonance response based on the high-resolution three-dimensional digital core

Simulation of nuclear magnetic resonance response based on the high-resolution three-dimensional digital core

On the evidence of helico-spiralling recirculation within coherent cores of eddies using Lagrangian approach

Oceanic eddies exhibit remarkable coherence and longevity compared to other transient features in the surrounding flow. They possess the ability to transport properties over extensive distances while maintaining their material identity intact. The Lagrangian Coherent Structure (LCS) framework has proven effective in capturing these coherent eddies, where they display a solid-body-like rotation. Although various LCS approaches have been employed to investigate different facets of coherent eddies, a comprehensive understanding of their three-dimensional structures and internal dynamics remains elusive. This study aims to advance our comprehension of coherent eddies’ structural characteristics and delve into the precise nature of their internal dynamics by utilizing the Lagrangian Averaged Vorticity Deviation approach. Two eddies, one cyclonic and the other anti-cyclonic, were chosen from a high-resolution simulation carried out in the Bay of Bengal using the Regional Ocean Modeling System (ROMS). The findings unveil that these eddies have three-dimensional coherent cores resembling gently tapered cones that are broader at the surface and gradually narrow towards the bottom. Intriguingly, the dynamically coherent core of these eddies exhibits simultaneous upwelling and downwelling while maintaining their volumes during advection due to persistent material coherence. The three-dimensional trajectories followed by the fluid parcels inside the coherent core are helical. Their two-dimensional horizontal projections show alternating spiral bands of upwelling and downwelling which are the manifestations of Vortex Rossby Waves. These observations lead to a conceptual framework of a three-dimensional helico-spiralling recirculation pattern within the coherent cores of eddies.

Effects of integrated intrinsic foot muscle exercise with foot core training device on balance and body composition among community-dwelling adults aged 60 and above

BackgroundEvidence on the effects of plantar intrinsic foot muscle exercise in older adults remains limited. This study aimed to evaluate the effect of an integrated intrinsic foot muscle exercise program with a novel three-dimensional printing foot core training device on balance and body composition in community-dwelling adults aged 60 and above.MethodsA total of 40 participants aged ≥ 60 years were enrolled in this quasi-experimental, single-group, pretest-posttest design; participants were categorized into two groups, those with balance impairment and those without balance impairment. The participants performed a 4-week integrated intrinsic foot muscle exercise program with a three-dimensional printing foot core training device. The short physical performance battery (SPPB) and timed up and go test were employed to evaluate mobility and balance. A foot pressure distribution analysis was conducted to assess static postural control. The appendicular skeletal muscle mass index and fat mass were measured by a segmental body composition monitor with bioelectrical impedance analysis. The Wilcoxon signed rank test was used to determine the difference before and after the exercise program.ResultsAmong the 40 enrolled participants (median age, 78.0 years; female, 80.0%; balance-impaired group, 27.5%), the 95% confidence ellipse area of the center of pressure under the eyes-closed condition was significantly decreased (median pretest: 217.3, interquartile range: 238.4; median posttest: 131.7, interquartile range: 199.5; P = 0.001) after the exercise. Female participants without balance impairment demonstrated a significant increase in appendicular skeletal muscle mass index and a decrease in fat mass. Participants in the balance-impaired group exhibited a significant increase in SPPB.ConclusionsIntegrated intrinsic foot muscle exercise with a three-dimensional printing foot core training device may improve balance and body composition in adults aged 60 and above.Trial registrationClinicalTrials.gov ID: NCT05750888 (retrospectively registered 02/03/2023).

Three-dimensional core shell InGaN/GaN heterostructure for color tunable emitters on the aspect ratio controlled GaN nanorods

In the pursuit of developing red, green and blue emitters, comprehension of color tunability in relation to the nanostructure properties is imperative. Hence, we present a systematic study for the fabrication of color tunable emitters based on GaN nanorods (NRs) prepared via two-step etching technique. In the essence of tunable emission wavelength, aspect ratio controlled GaN NRs were employed for the growth of core shell heterostructure of InGaN/GaN multiple quantum wells (MQWs) using MOCVD and the impact of aspect ratio regulation on the emission wavelength modulation was studied. To analyze the role of the GaN NRs aspect ratio in facilitating the tunable emission wavelength, we employed metrological as well as optical characterizations. Photoluminescence spectra results established a direct relation of the aspect ratio to the emission profile of the GaN NRs. Furthermore, power-dependent photoluminescence (PL) and cathodoluminescence (CL) studies clarified the source of the emission, providing confirmation of the active region's exclusive growth on non-polar sidewalls and the absence of polarization-induced fields. Tunneling microscope measurements revealed a direct relation of the GaN NRs aspect ratio to the emission wavelength profile. In conclusion, we studied comprehensively the impact of aspect ratio regulation for the tunable emission wavelength.

A Multilevel Approach for Direct Core Calculation Schemes

A method of dynamic homogenization was recently proposed as an alternative technique for three-dimensional (3D) core calculations using a direct approach. This technique allows for producing homogenization parameters for a subdomain within the core at its actual state, and offers the advantage of avoiding off-line calculations, cross-section interpolations, and expensive 3D transport calculations. The methodology has shown a remarkable reduction in computational cost compared to 3D transport. However, the application of direct calculation schemes in multiphysics and multicycle problems still demands an extensive use of computational resources. Within the framework of traditional two-step calculations, several multilevel schemes have been developed to accelerate lattice calculations for the generation of the multiparameter cross-section libraries. With a similar objective, this work investigates how the multilevel approach can be applied within the framework of direct calculation schemes and discusses how depletion calculations may be performed. The objective is to enhance their performance and reduce memory requirements in favor of a high-fidelity model of the matter behavior in the reactor. We have then identified suitable flux solvers for each level and explored various homogenization options. We tested the methodology in a 3D pressurized water reactor core problem inspired by the TVA Watts Bar Unit 1 Multi-Physics Multi-Cycle OECD/NEA Benchmark, and performed a comparative analysis to assess the accuracy and computational efficiency of these new calculation schemes against direct single-level calculations and a two-step calculation based on pin-by-pin homogenization, as well as Monte Carlo simulations. Our analysis proves that the computational resources required to solve the full-core problem using a multilevel scheme are significantly reduced, and the best computational features are provided by multilevel dynamic homogenization. Furthermore, we observed that the multilevel approach not only allows for speedup, but can also be advantageously applied in order to improve the accuracy of the final solution of a calculation scheme when the core solver relies on an approximate transport operator.

Characterization and Quantitative Assessment of Shale Fracture Characteristics and Fracability Based on a Three-Dimensional Digital Core

At present, assessment techniques for the fracability of shale reservoirs, which rely on the formation of an effective fracture network, are scarce. Hence, in order to assess the fracability, it is critical to establish a quantitative correlation between the pattern of fracture distribution after fracture and fracability. The present investigation utilizes three-dimensional digital core technology and triaxial compression experiments to simulate the fracturing process in typical domestic shale reservoir cores. In addition to utilizing the maximum ball algorithm to extract fracture images, a number of other techniques are employed to compute the spatial quantitative parameters of the fractures, including least squares fitting, image tracking algorithms, and three-dimensional image topology algorithms. The introduction of the notion of three-dimensional fracture complexity serves to delineate the degree of successful fracture network formation subsequent to fracturing. A quantitative fracability characterization model is developed by integrating the constraints of fracture network formation potential and fragmentation potential. The results of this study show that the quantitative characterization of the characteristic parameters of cracks can be achieved by establishing a method for extracting crack information as well as parameters after core compression and completing the construction of a three-dimensional complexity characterization model. Meanwhile, the three-dimensional post-compression fracture image validation shows that the core fracturability index can better reflect the actual fracturing situation, which is in line with the microseismic monitoring results, and significantly improves the accuracy of fracturability characterization, which is an important guideline for the fracturing design of shale gas reservoirs.

Enhanced optical vector bottle beams with obscured nodal surfaces

Optical bottle beams, characterized by their unique three-dimensional dark core, have garnered substantial interest due to their potential applications across multiple domains of science and technology. This paper delves into the current methods used to create these beams and provides a method to obscure their nodal planes through coaxial non-interfering orthogonally polarized beams to generate bottle beams with enhanced uniformity. Experimental and theoretical results show the enhanced vector bottle beam maintains a smaller, more spherically uniform potential well and interesting quasi-particle polarization characteristics.

Super-resolution reconstruction of 3D digital rocks by deep neural networks

Digital rock technology provides valuable insights into the pore structure and fluid flow properties of geoenergy resources. Artificial intelligence technology in vision and image processing, especially the image super-resolution, has great potential for digital rock reconstruction and resolution enhancement. However, the analyzed core samples are typically sandstones/carbonates in micro-scale resolutions and in two-dimensional (2D) space, whereas the shale rocks in nano-scale resolutions for unconventional resources or three-dimensional (3D) digital cores are rarely investigated. Additionally, previous studies primarily emphasized image quality from a computer vision perspective, with little consideration given to estimating physical properties of digital rocks using super-resolution techniques.This study presents a very deep super-resolution (VDSR) algorithm, specifically designed to generate high-resolution 3D digital rock images, for nano-scale shale matrix and micro-scale hydraulic fractures. We compare both image quality and permeability accuracy between the original high-resolution images and the super-resolution images reconstructed by the proposed method. The results reveal that the reconstructed images using the proposed method closely resemble the actual images, and effectively reduce errors in permeability computations. This study highlights the applicability of the proposed VDSR algorithm in establishing the detailed structures of 3D nano-scale shale matrix and hydraulic fractured rocks, thus advancing super-resolution techniques in digital core analysis for geoenergy resources development.

Three-Axis Vector Magnetometer with a Three-Dimensional Flux Concentrator.

This research proposes a magnetic field sensor with spatial orientation ability. Through the assistance of a magnetic flux concentrator, out-of-plane magnetic flux can be concentrated and guided into the planar magnetic cores of a fluxgate sensor. A printed circuit board is used to construct the basic planar structure, on which the proposed three-dimensional magnetic flux concentrator and magnetic cores are assembled. This reduces the alignment error of the coils and improves the reliability of the sensor. Three-axis sensing is achieved by using the second harmonic signals from selected sensing coil pairs. The magnetometer exhibits a linear range to 130 μT. At an excitation frequency of 50 kHz, the measured sensitivities are 257.1, 468.8, and 258.8 V/T for the X-, Y-, and Z-axis sensing modes, respectively. This sensor utilizes only one sensing mechanism for the vector field, making it suitable for IoT applications, especially for assessing mechanical posture or position.

On the Use of the Jacobian-Free Newton Krylov Method to Generate One-Group Discontinuity and Super Homogenization Factors for Full-Core Neutron Diffusion Simulations

Coupled Monte Carlo (MC) and thermal-hydraulic analysis is valuable as a design or reference tool but can be slow, especially when implemented in a Picard iteration. Previous work has developed a novel prediction block to achieve convergence with fewer MC simulations. The prediction works in two stages: (1) a surrogate-like model predicts macroscopic cross sections on the fly and (2) a reduced-order neutronic model predicts the flux response to the updated cross sections. The main challenge with the prediction block is that the reduced-order neutronic model cannot reproduce the spatial flux distribution with high fidelity. This paper investigates the well-established Jacobian-free Newton Krylov (JFNK) method to preserve equivalency between a homogeneous (nodal diffusion) solution and a high-fidelity transport (MC) solution. Instead of performing multiple computationally consuming MC simulations, the nonlinear iterative approach iterates on correction parameters, e.g., assembly discontinuity factors (ADFs) or super homogenization (SPH) factors, using unexpensive nodal solutions. The JFNK approach does not require additional overhead from the MC solver to generate flux tallies. Further, the approach iterates on diffusion solutions produced directly from a desired code, thus ensuring that the parameters are compatible with that code. The approach is applied to correct a nodal diffusion solution for a realistic three-dimensional pressurized water reactor core. The results obtained in the paper show that the method is very successful in reproducing the heterogeneous solution (up to 2.5% difference in assembly flux for SPH and 0.3% for ADFs) without needing to modify the source code of the nodal diffusion solver. In addition, the results show that ADFs yield the best agreement and are also stable (i.e., weakly varying) when thermal-hydraulic fields are perturbed.

Seismic sedimentology response characteristics of nearshore terminal fan in the suning area of Raoyang Sag, Bohai Bay Basin, NE China

A nearshore terminal fan is a special water system formed in arid environments. The characterisation of its thin-channel sand bodies has long been a challenge restricting oil and gas exploration. This study takes the Suning area of the Raoyang Sag as an example and uses the principles of seismic sedimentology to conduct seismic sedimentary research on the nearshore terminal fan of the first member of the Palaeogene Shahejie Formation (Es1) based on three-dimensional seismic, logging, and core analysis. Seven fourth-order sequences (SQV7) were identified within Es1, deposited by a fluvial river system terminating at the contracting bank of a lake. Prograding terminal fan sedimentary facies on a gentle slope zone were observed in the root mean square seismic attributes after spectral decomposition. We have successfully resolved the sandstone within the studied terminal fan system using a 90° phase conversion of the seismic data and red-green-blue (RGB) fusion of the various seismic attributes. The upper subsegment of the Shahejie Formation developed extensive nearshore terminal fan sedimentation, and the seismic sedimentological response characteristics were mainly channel-like and strip-shaped geomorphic systems deposited on gentle slope zones, indicating distributary channels and distal basin sedimentation. This study enriches our understanding of nearshore fans and provides ideas for predicting favourable sand bodies in this type of sedimentary facies.

Three-Dimensional Spatial Microscopic Characteristics and Developmental Influencing Factors of Tight Gas Layers in Hangjinqi Prospect Area, Ordos Basin, China

The unconventional tight oil and gas resources in the Xinzhao East belt of the Hangjinqi Prospect area in the Ordos Basin of China are abundant. However, the reservoir’s internal storage space is complex, and the microscopic pore throat structural features are not well recognized, which has led to some trouble in the deployment of oil and gas exploration. To reveal the microscopic characteristics of the dense sandstone gas layer in the first member of the Lower Stone Box Formation of the D-well Zone in the Xinzhao East belt of the Hangjinqi Prospect area, a three-dimensional space digital core was built, and the stored set spatial data were extracted, based on rock sheet and coring data and X-CT scanning technology. Quartz grain size was segmented and analyzed based on an adaptive approach. The microscopic characteristics of the gas layer in the studied section and the factors influencing its development were studied, combining the use of a field emission scanning electron microscope, helium porosimeter, and gas permeability meter. We found that in the studied section, the porosity is relatively high, the pore throat size is large, and the pore permeability correlation is good. The reservoir space, which consists of intergranular pores, intragranular pores, and microcracks at the grain edges in the study area, is characterized by a complex distribution pattern. Within the gas layer, isolated pores are connected by microcracks to form a network of reservoir spaces, which increases the pore throat size, enhances the connectivity of the pore throat, and makes the microscopic characteristics of the reservoir space better. The first member of the Lower Stone Box Formation could be an advantageous reservoir. Hole–throat connectivity is poor because of the gas layer having underdeveloped primary pores, the blockage of pores by unstable minerals (kaolinite, etc.), and poorly connected pore throats based on insoluble mud cementation. The high content of quartz brittle minerals and the development of natural microcracks within the gas formation are favorable conditions for fracking development. The quartz grain size within the gas layer is positively correlated with the pore throat size, which suggests that the quartz grain size somewhat influences the microscopic characteristics of the reservoir space. This comprehensive study shows that the methodology of the study is more advantageous than traditional methods in the fine and three-dimensional spatial characterization of the microstructure of dense sandstone reservoirs. The research results of this paper have certain guiding significance for further reservoir evaluation and advantageous reservoir prediction in the Hangjinqi Prospect area in the Ordos Basin. We also provide the basis for the subsequent efficient development of the gas reservoir.

Magnetostrictive Vibration Characteristics of Amorphous Alloy Transformer With Three-Dimensional Wound Core

Magnetostrictive Vibration Characteristics of Amorphous Alloy Transformer With Three-Dimensional Wound Core

Structure optimization design and magneto-mechanical characteristics analysis of amorphous alloy with oriented silicon steel composite wound core

Three-dimensional wound cores are widely used in three-phase distribution transformer due to the symmetrical magnetic circuit structure. Amorphous alloy and oriented silicon steel are two kinds of ferromagnetic materials commonly used to make distribution transformer cores, each has own advantages and disadvantages in magnetic and mechanical characteristics. The amorphous alloy and oriented silicon steel composite core can synthesize the advantages of both. In this paper, a double-layer composite wound core (DCWC) structure is proposed and the corresponding dual nonlinear electric circuit and magnetic circuit coupling model is established. A structure optimization design method for the DCWC based on the free parameter scanning method is proposed by taking the percentage of oriented silicon steel in the composite core and the structure parameters as free variables. Based on the proposed optimization design method, a DCWC is designed and the experimental prototypes are manufactured. Further, the flux density distribution, core loss and mechanical vibration displacement of the DCWC are analyzed, and the effectiveness of the proposed method is verified by comparing with the measured results.