International Journal of Applied Electromagnetics and Mechanics - Volume Pre-press, issue Pre-press

Authors: Iwamoto, Yuhiro | Nakasumi, Hayaki | Ido, Yasushi | Yamaguchi, Hiroshi

Article Type: Research Article

Abstract: Mn-Zn ferrite-based magnetic fluid is temperature-sensitive. Because of the low Curie temperature of Mn-Zn ferrite particles, magnetization is dramatically attenuated as the temperature rises. This temperature-dependent magnetization can be used to transport heat by magnetically driving a fluid via the application of a non-uniform magnetic field and heat. A potential application of this scheme is long-distance heat transport without the use of mechanical pumps. In the present work, a miniaturized magnetically-driven heat transport device with an inner diameter of 𝜙1.54 mm and a flow path length of 1,500 to 6,000 mm was fabricated. The influence of flow path length on the flow …rate induced by the magnetic body force was investigated experimentally and theoretically. Although the flow rate decreased with increasing flow path length due to friction loss, the driving pressure increased with rising heater temperature because of the temperature-dependent magnetization. The influence of flow path length on the driving pressure is relatively insignificant. An increase in the flow path length leads to effects that both attenuate and enhance the driving pressure. Substantial long-distance (6,000 mm) heat transport was realized by applying a non-uniform magnetic field and heat. Show more

Keywords: Magnetic nanofluid, heat transfer, magnetic fluid, temperature-dependent magnetization, energy conversion

DOI: 10.3233/JAE-190033

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. Pre-press, no. Pre-press, pp. 1-14, 2019

Authors: Yan, Dong | Guo, Liyan | Shi, Tingna | Wang, Huimin | Yan, Yan | Xia, Changliang

Article Type: Research Article

Abstract: The split ratio is one of the most important design parameters of the machines and has a significant effect on the electromagnetic performance. Using the split ratio, this paper presents a performance analysis method for permanent magnet (PM)-assisted reluctance machine is presented. An accurate analytical model, which considers the saturation of outer iron ribs and the asymmetric saturation of rotor islands, is firstly proposed. In order to reduce the numbers of the adjustable structural parameters during the initial design process and ensure the independence among the parameters, a geometric structure corresponding to the split ratio is then established. The effectiveness …of the proposed analytical model based on the split ratio is verified by FEM, and applied to analyze the electromagnetic performance for the three-flux-barrier PM-assisted reluctance machines. On the basis of the analysis results, the design scheme corresponding to the optimal split ratio, which makes the machine obtain a higher efficiency and guarantees the PMs without irreversible demagnetization, is determined rapidly. Show more

Keywords: Permanent magnet (PM)-assisted reluctance machine, the gradient flux barrier, split ratio, analytical model

DOI: 10.3233/JAE-190104

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. Pre-press, no. Pre-press, pp. 1-25, 2019

Authors: Yan, Xinxiao | Li, Yongjian | Cheng, Zhiguang | Zhang, Changgeng

Article Type: Research Article

Abstract: A 3-D coupled magneto-fluid-thermal model is established for temperature rise prediction in a ventilated dry-type transformer rated at 2500 kVA. In order to accurately estimate electromagnetic losses, a three-dimensional (3-D) transient finite element method considering the effect of eddy-current losses on the foil type windings is proposed. Besides, two orthogonal B -P loss curves are adopted to model the anisotropy of grain-oriented (GO) silicon steel. The non-uniform power losses of winding and core are mapped into the thermal field as heat sources. Moreover, the transformer structures such as the narrow struts, insulation barrier and clamps are considered to improve the …computational accuracy of air velocity and temperature distribution. At last, the test of temperature rise has been carried out to verify the proposed model. Show more

Keywords: Dry-type transformer, eddy currents, power losses, magnetic measurements

DOI: 10.3233/JAE-190054

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. Pre-press, no. Pre-press, pp. 1-11, 2019

Authors: Zhao, Jianhui | Yue, Pengfei | Wei, Kebiao

Article Type: Research Article

Abstract: A high-speed solenoid valve (HSV) with high dynamic responses is a key component of the common rail injector, where it provides accurate and flexible control of the injection. In this study, finite element methods were used to investigate the eddy current inside an HSV. The results demonstrated that the appearance and change in the eddy current were related to the driving current, and significantly influenced the HSV dynamics, particularly the opening response. By considering the eddy current effect, the calculations were seen to match the experimental data effectively during the opening response, but did not match them strongly during the …closing response. During the HSV opening process, the eddy current at the surface of the magnetic materials impeded the magnetization; during the closing stage, it prevented the magnetic flux inside the magnetic material from spreading out and delayed demagnetization. An eddy current was proven to always block the magnetic field change and worsen the HSV dynamic response. Slotting on the yoke can significantly reduce the open response time, while hardly influence the close response. It was deemed necessary to optimize the HSV structure to weaken the eddy current effect on the opening and closing response. Show more

Keywords: eddy current effect, dynamic response, high-speed solenoid valve, common rail injection system, diesel engine

DOI: 10.3233/JAE-190047

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. Pre-press, no. Pre-press, pp. 1-10, 2019

Authors: Guo, Yujing | Jin, Ping | Ding, Yan | Zhao, Kai | Issoufou, Abdoul Zaid

Article Type: Research Article

Abstract: In this paper, one kind of U-shape permanent magnet embedded salient pole wind generator is proposed. The permanent magnet is divided into three sections to form a U-shaped structure and inserted into the salient pole in the generator. The size of the PM near the side frame is small, therefore, there is sufficient PM location modification space in the salient pole. Some flux-barriers are set in the upper core of the salient pole, which can reduce the q -axis inductance, and ultimately increases the generator maximum output power. To evaluate the generator’s overall performance, some other important electromagnetic parameters such …as the air-gap flux density, the output voltage, the cogging torque, the output power, and the demagnetization performance are all calculated and analyzed base on finite element method (FEM). All the above parameters are compared with that of one V-shape permanent magnet embedded salient pole wind generator. The analysis results show that, with the same volume of permanent magnet, the proposed U-shape permanent magnet embedded salient pole wind generator has higher power density than the V-shape permanent magnet embedded salient pole wind generator. Show more

Keywords: Electromagnetic parameter analysis, reluctance power, salient pole, wind generator

DOI: 10.3233/JAE-190026

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. Pre-press, no. Pre-press, pp. 1-11, 2019

Authors: Sun, Hongyu | Wang, Shen | Huang, Songling | Wang, Qing | Zhao, Wei

Article Type: Research Article

Abstract: Electromagnetic ultrasonic testing, based on the propagation characteristics of the ultrasonic wave in the medium, is an effective technique for defect detection. The structural of the electromagnetic acoustic transducer (EMAT) determines the detection effect, which should be reasonably designed. We propose an improved unilateral point-focusing EMAT structure with curved coils in this manuscript. The 3D model of the designed EMAT is numerically simulated utilizing the finite element method, and the bilateral point-focusing EMAT is also studied for comparison. The simulation results of the magnetic field intensity and the distributions of the displacement are shown in the manuscript, which prove the …effectiveness of the improved unilateral point-focusing EMAT. Five impact parameters such as aperture angle, focal position, excitation current, lift-off distance, and coil winding number are investigated in detail. We verify the calculation results of the aperture angle and excitation current by the experiments. The conclusion shows that the focusing intensity of the improved unilateral point-focusing EMAT is relatively higher, and other factors also have a significant effect on the focal intensity. Show more

Keywords: Point focusing, electromagnetic acoustic transducer (EMAT), unilateral, bilateral, numerical simulation

DOI: 10.3233/JAE-190071

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. Pre-press, no. Pre-press, pp. 1-18, 2019

Authors: Yang, Yiyi | Su, Sanqing | Wang, Wei | Ma, Xiaoping | Hu, Jingyu

Article Type: Research Article

Abstract: Metal magnetic memory (MMM) testing method has been proved to be a valid approach to monitor early damage and predict fatigue life, but there is no systematic description and comparison about the characteristics of MMM signals for welding and non-welding specimens with different materials under tension-compression fatigue. Thus, the fatigue tests for Q345B and Q345qC welding and non-welding specimens were carried out and the MMM testing was done synchronously. Then, based on the normal components of MMM signals, H p (y ), and its variations, ΔH p (y ), the slope of ΔH p (y ) fitting …curves, K C , and the average of ΔH p (y ) signals on the whole testing line, ΔH p (y )ave , were extracted as the characteristic parameters for Q345B and Q345qC non-welding specimens, respectively. Additionally, the gradient of “peak–vale” on H p (y ) signals curves, k , and the average of H p (y ) signals in the scope of welding zone, H p (y )ave , were extracted as the characteristic parameters for Q345B and Q345qC welding specimens, respectively. Some conclusions can be drawn by comparison: the variation laws of H p (y ) signals with cyclic loads are related to the material. The characteristic parameters for welding and non-welding specimens with the same material have a certain similarity. Then, the failure of non-welding steel can be warned early by K C or ΔH p (y )ave when the fatigue life has 20% left, but the damage degree of welding specimen should begin to be valued highly once the k or H p (y )ave is decreasing. Finally, the fatigue life of welding and non-welding specimens with different materials can be evaluated effectively by using corresponding magnetic characteristic parameters. Show more

Keywords: Metal magnetic memory (MMM) testing, fatigue life, magnetic characteristic parameter, Q345B and Q345qC steel, weldments

DOI: 10.3233/JAE-190064

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. Pre-press, no. Pre-press, pp. 1-25, 2019

Authors: Park, Eui-Jong | Jung, Sang-Yong | Kim, Yong-Jae

Article Type: Research Article

Abstract: The magnetic gears which can replace the mechanical gear system are actively studied recently. Improving the power density is growing importance because the characteristics that as gear ratio grows so power density decreases were observed. This paper analyzes the various characteristics (power density, efficiency, torque ripple, loss, and so on) according to the gear ratio in detail, and proposes a concept that high gear ratio by combining two low gear ratio. A target gear ratio is 10 to 1 and application is 1 kW wind turbine. To obtain the optimal combination, 30 gear ratios were considered, and initial design process was …shown about this concept to propose the direction of improving the power density. All models were analyzed with 2D-FEM by numerical analysis. Show more

Keywords: Finite element analysis, magnetic gears, power density, high gear ratio

DOI: 10.3233/JAE-190097

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. Pre-press, no. Pre-press, pp. 1-10, 2019

Authors: Toghraie, Davood

Article Type: Research Article

Abstract: Optimization of the cooling processes by fluids in many industries such as power generation, transportation, machining, and electronics is very important. Heat transfer equipment to achieve higher efficiency, need to downsizing of the equipment, and increase the heat transfer rate per unit of surface. The aim of this paper is to investigate the effect of MHD mixed convection flow of Cu-water nanofluid in a trapezoidal lid-driven cavity with different tilt angles in a range of 0° to 60°. The cavity consists of the non-uniformly heated bottom wall, insulated top wall, and isothermal sidewalls. The governing equations of the flow by …using the finite volume method and the SIMPLE algorithm have been numerically solved. The studies for the wide range of Richardson number (Ri) from 0.01 to 10, volume fraction of nanoparticles from 0.1% to 4% and Hartman number (Ha) from 0 to 40 in the steady-state have been done. Result in the form of streamline, vorticity and temperature contours for three geometry, local Nusselt number graphs for non-uniformly heated bottom surface and velocity profile on the vertical centerline of the cavity in different geometry have been investigated. The results show that the average Nusselt number on the non-uniformly heated bottom wall is dependent on dimensionless parameters and tilt angles. Also, applying a magnetic field, reduce the velocity profile changes, and using nanoparticles will cause increasing the Nusselt number. Show more

Keywords: Mixed convection, magneto-hydrodynamic, trapezoidal cavity, non-uniformly heated surface

DOI: 10.3233/JAE-190123

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. Pre-press, no. Pre-press, pp. 1-28, 2019

Authors: de Souza Lima, Diorge | Mahmud, Lucas S. | de Sousa, Antonio R. M. | da S. Fonseca, Wellington | Bezerra, Ubiratan Holanda | Bezerra, Fábio Vinícius V.

Article Type: Research Article

Abstract: Sympathetic inrush current phenomenon occurs when a transformer is switched on in a power network containing other transformers that are already energized. This interaction significantly changes duration and magnitude of transient magnetizing currents in the transformers involved and may lead to misoperation of these equipment. Therefore, in this paper it is presented the results of electromagnetic analysis due to sympathetic inrush and inrush current phenomenon among single-phase 50 MVA transformers in a power substation in the northern region of Brazil. For this purpose, the nine single-phase transformers installed at SE Guamá forming three three-phase banks, were modeled in the ATP software …to obtain the energization behavior. In this paper the electromagnetic analyzes are performed in steady state, so only the first peak is used. In this way, results of the electromagnetic behavior of transformers are presented and compared sympathetic inrush with inrush current. Show more

Keywords: Sympathetic inrush, transformers bank, MEF, ATP software

DOI: 10.3233/JAE-190041

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. Pre-press, no. Pre-press, pp. 1-16, 2019