scholarly journals Analysis of Opening Angle for Radial Magnetic Field Compensation Windings of Double-layer Ferromagnetic Cylindrical Shells

2021 ◽  
Vol 2068 (1) ◽  
pp. 012018
Author(s):  
Chao Zuo ◽  
Meng Chen ◽  
Hanchen Xiao ◽  
Pan Geng
Keyword(s):  
Magnetic Field ◽  
Cylindrical Shell ◽  
Shell Model ◽  
Double Layer ◽  
Geomagnetic Field ◽  
Opening Angle ◽  
Local Magnetization ◽  
Radial Magnetic Field ◽  
Surrounding Space ◽  
Single Branch

Abstract A double-layer ferromagnetic cylindrical shell causes a magnetic anomaly in its surrounding space under the action of the geomagnetic field. Aiming at the problems of poor compensation uniformity and obvious local magnetization caused by the single-branch winding compensation method, a double-branch winding solution is proposed. By establishing a double-layer ferromagnetic cylindrical shell model, the radial magnetization characteristics of the cylindrical shell under the action of the vertical geomagnetic field was analyzed, and the opening angle of double-branch winding was studied. By optimizing the opening angle of compensation windings in the three proposed configuration schemes with respect to the minimum abnormal magnetic field, the optimal ranges of opening angle for the double-branch compensation windings were determined.

scholarly journals Predictions of the geomagnetic secular variation based on the ensemble sequential assimilation of geomagnetic field models by dynamo simulations

2020 ◽  
Vol 72 (1) ◽  
Author(s):  
Sabrina Sanchez ◽  
Johannes Wicht ◽  
Julien Bärenzung
Keyword(s):  
Magnetic Field ◽  
Secular Variation ◽  
Geomagnetic Field ◽  
Wave Number ◽  
Main Magnetic Field ◽  
Candidate Model ◽  
Uncertainty Estimates ◽  
Geomagnetic Field Models ◽  
Dipole Configuration

Abstract The IGRF offers an important incentive for testing algorithms predicting the Earth’s magnetic field changes, known as secular variation (SV), in a 5-year range. Here, we present a SV candidate model for the 13th IGRF that stems from a sequential ensemble data assimilation approach (EnKF). The ensemble consists of a number of parallel-running 3D-dynamo simulations. The assimilated data are geomagnetic field snapshots covering the years 1840 to 2000 from the COV-OBS.x1 model and for 2001 to 2020 from the Kalmag model. A spectral covariance localization method, considering the couplings between spherical harmonics of the same equatorial symmetry and same azimuthal wave number, allows decreasing the ensemble size to about a 100 while maintaining the stability of the assimilation. The quality of 5-year predictions is tested for the past two decades. These tests show that the assimilation scheme is able to reconstruct the overall SV evolution. They also suggest that a better 5-year forecast is obtained keeping the SV constant compared to the dynamically evolving SV. However, the quality of the dynamical forecast steadily improves over the full assimilation window (180 years). We therefore propose the instantaneous SV estimate for 2020 from our assimilation as a candidate model for the IGRF-13. The ensemble approach provides uncertainty estimates, which closely match the residual differences with respect to the IGRF-13. Longer term predictions for the evolution of the main magnetic field features over a 50-year range are also presented. We observe the further decrease of the axial dipole at a mean rate of 8 nT/year as well as a deepening and broadening of the South Atlantic Anomaly. The magnetic dip poles are seen to approach an eccentric dipole configuration.

Analysis of Cogging Torque of PM Motor with Radial Magnetic Field and Parallel Magnetic Field

2011 ◽  
Vol 105-107 ◽  
pp. 2289-2294
Author(s):  
Jun Qiang Lian ◽  
Shun Yi Xie ◽  
Jian Wang
Keyword(s):  
Magnetic Field ◽  
Air Gap ◽  
Analytic Method ◽  
Analytic Model ◽  
Parallel Magnetic Field ◽  
Radial Magnetic Field ◽  
Fem Model ◽  
Cogging Torque ◽  
Fem Method

This paper provide two methods to analyze the cogging torque of PM motor with radial magnetic field and parallel magnetic field, FEM method and Analytic method. The FEM model and Analytic model of PM motor with radial magnetic field and parallel magnetic field are founded. We analyze the model in both methods. From the result of analysis. The air-gap magnetic density of PM motor can be analyzed. We can find the cogging torque of radial magnetic field PM motor is much heavily than the cogging torque of parallel magnetic field PM motor. The result of Analytic method is close to the result of FEM method. The Analytic method is useful in analyze the cogging torque of PM motor.

Magnetohydrodynamic lubrication flow between parallel rotating disks

1962 ◽  
Vol 13 (1) ◽  
pp. 21-32 ◽  
Author(s):  
W. F. Hughes ◽  
R. A. Elco
Keyword(s):  
Magnetic Field ◽  
Axial Magnetic Field ◽  
Load Capacity ◽  
Electrical Energy ◽  
Axial Current ◽  
Frictional Torque ◽  
Rotating Disks ◽  
Radial Magnetic Field ◽  
Electrically Conducting ◽  
Parallel Disks

The motion of an electrically conducting, incompressible, viscous fluid in the presence of a magnetic field is analyzed for flow between two parallel disks, one of which rotates at a constant angular velocity. The specific application to liquid metal lubrication in thrust bearings is considered. The two field configurations discussed are: an axial magnetic field with a radial current and a radial magnetic field with an axial current. It is shown that the load capacity of the bearing is dependent on the MHD interactions in the fluid and that the frictional torque on the rotor can be made zero for both field configurations by supplying electrical energy through the electrodes to the fluid.

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