Translator Eccentricity Analysis in Tubular Linear Machines using Quasi-3D Finite Element Method Modeling

A quasi-3D model has been developed to simulate the flow in planar microfluidic systems with low Reynolds numbers. The model was developed by decomposing the flow profile along the height of a microfluidic system into a Fourier series. It was validated against the analytical solution for flow in a straight rectangular channel and the full 3D numerical COMSOL Navier-Stokes solver for flow in a T-channel. Comparable accuracy to the full 3D numerical solution was achieved by using only three Fourier terms with a significant decrease in computation time. The quasi-3D model was used to model flows in a micro-flow cytometer chip on a desktop computer and good agreement between the simulation and the experimental results was found.

In this paper, the effects of permanent magnet synchronous motor (PMSM) static eccentricity faults on the air gap flux density, flux linkage, electromotive forces (EMFs) and electromagnetic torque (EM torque) have been presented. A 2D finite element method (FEM) is needed for PMSM modeling under healthy and faulty conditions. The achieved simulation results under different static eccentricity severities show how eccentricity affect the performance of the studied motor.

Aiming at the problems that the coaxial magnetic gear (CMG) has lower torque density and higher eddy current loss, a relation model between the effective components of the modulation magnetic field and the original field is deduced based on the calculation method of the air gap flux density of the permanent magnetic motor and its unilateral grooved air gap permeance. According to this model, the modulation effect of the modulating ring is the best when the original magnetic air gap field of the permanent magnetic ring in CMG is close to sinusoid. Hereby a new topology is proposed where the traditional yoke magnetic conductive structure is replaced by the structure of the permanent magnet itself, thus the permanent magnet of the permanent magnetic ring in CMG would be of a higher utility rate of space and form a more ideal air gap magnetic field. Using control variable method (CVM), 2D finite element method (2D FEM) and fast Fourier transform (FFT), the simulated analysis between the old and the new structures proves that when without a modulating ring, the original air gap magnetic field formed by the traditional yoke magnetic conductive structure is square wave, whose magnetic field modulated by the modulating ring is mainly composed of harmful fundamental wave. Meanwhile, however, the new topology presented is of an original air gap magnetic field closer to the ideal sinusoid, and the modulated magnetic field of which is mainly composed of harmonic wave coupling with the permanent magnet on the permanent magnetic ring of the other side. Taking advantage of CVM and 2D FEM, the performance differences of the old and the new structures are analyzed on the aspects such as torque density and eddy current loss, and the results show that with the same inner and outer rotor volume, as more permanent magnets could be placed, the new topology is of a higher torque density. Moreover, the increase of the torque density lessens the volume of the outer magnetic ring, thus lessening its change of flux. As a result, with identical speed and maximum torque, the eddy current loss of the new structure is also lower.

CFD Simulations of Abnormal Flow in Horizontal Pipes for Offshore Hydrocarbon Transport

The fabricated 3D-printed bolus with 5 mm thick PLA and TPU materials was successfully used to analyze the air gap, relative electron density ( RED), and mass attenuation coefficient values for Post-Mastectomy Breast Cancer Radiation Therapy (PMRT). The 3D bolus was designed using 3D-Slicer Segment Editor software according to the thickness used, then smoothed and finished using Autodesk Meshmixer software, and printed on a 3D Creality printer. The air gap value was then analyzed by taking images from the phantom and 3D-printed bolus on a CT-Scan, then processed on Radiant DICOM, and the air gap value for the two 3D bolus materials was obtained. Analysis of two 3D bolus materials, PLA and TPU, showed that TPU is more suitable for bolus use in postmastectomy breast cancer cases based on its material properties. In addition, TPU is also better in terms of the air gap value because it has a smaller air gap, an RED value that is almost close to that of breast tissue, and better mass attenuation. Therefore, the recommended 3D-printed bolus material is TPU with a thickness of 5 mm as a tissue substitute for postmastectomy breast cancer cases.

This paper addresses the estimation of the 3D air gap field for Ironless Rotor Double Stator axial flux Permanent Magnet machines: the described method is based on a coulombian representation of the Permanent Magnets and the mirror theory. This approach can take into account the significant 3D effects that can occur in machine with very large air gap (that might be used in wind or tidal energy harnessing). For validation purpose, a laboratory prototype has been manufactured, the machine being characterized by the possibility of changing the air gap values. For several air gap values, experimental and calculated no load voltages are in good agreement, thus showing the ability of the focused calculation method to evaluate the performances of these particular machines.

When a conductive plate moves above a Halbach magnetic source, a magnetic field will be created in the air gap. This field induces eddy currents in the plate and creates drag and lift forces simultaneously. This phenomenon may be applied into eddy current brakes, couplings or magnetic levitation systems. In this paper, by utilizing the derived analytical field solutions of the Maxwell equations with magnetic scalar potential and magnetic field strength, the 3D lift and drag forces, and the flux density distribution in the air gap are predicted and analysed in the steady-state condition. Calculation results produced by analytical model are compared with those from the 3D finite element method. A prototype of the disk-type permanent magnetic eddy-current coupling has been manufactured to validate the accuracy of the 3D analytical model. The results confirm that, compared with 2D analytical model from the papers that had already published, the results calculated by the 3D analytical model have a higher accuracy in performance analysis. Finally, the characteristics of different kinds of magnet arrays are compared based on the proposed model, and several main problems are analysed and discussed.

This paper attempts to present a quasi-3D finite element method technique for modeling and analyzing tubular linear permanent magnet machines (TLPM) with translator eccentricity. Normal tubular linear machines can be modeled effectively using 2D axisymmetric models, but with the introduction of the eccentricity factor into the geometry the axis symmetry is no longer valid, and hence 3D modeling techniques become the only way for studying the machine. However, sometimes 3D modeling can become time-consuming and requires a huge amount of resources especially for non-linear problems, so the interest in modeling techniques that can represent the problem at hand with less computation time and relatively accurate results is high. A quasi-3D technique was specifically developed to be able to represent the eccentricity in TLPMs. The finite element method (FEM) was used for modeling. Eccentricity analysis has been carried on two different TLPM structures using the proposed quasi-3D, and the results from the quasi-3D model were compared to those obtained using the 3D FEM model. Both the open circuit and the on-load operating conditions were studied with the magnetic saturation taken into account. The behavior and the accuracy of the proposed model varied between the two studied structures and for the different operating conditions, and with very low computation time and cost the results obtained from the quasi-3D model were satisfactory in general except for certain cases.

Quasi-3D model for calculation of radiation leakage currents in modern submicron Silicon-on-Insulator (SOI) metal–oxide–semiconductor field-effect transistor (MOSFET) structures is proposed. The solution of a complex 3-dimensional problem is reduced to solving two tasks: 2D modeling of the traditional MOSFET cross-section and 3D modeling of the side parasitic transistor. The radiation-induced leakage current simulation in the 0.35 μm SOI MOSFET structure with taking account ionizing radiation with a dose of up to 500 krad was simulated. The results of the simulation show that in comparison with the traditional fully 3D modeling, which requires 11 hours of computer time, the computer time for the IdVg characteristic was reduced to 71 minutes (i.e. the computer time decreased by 9 times).

According to the novel structure of Axial-Radial Flux Type Fully Superconducting Synchronous Motor (ARFTFSSM), the 3D transient electromagnetic field mathematics model of the High Temperature Superconducting (HTS) synchronous motor integrated with HTS armature windings in the stator and HTS field coils in the end cover is established. No-load and load flux distributions, no-load properties, no-load flux densities in air gap and magnetic end ring, and electromagnetic torque under different armature currents are obtained by 3D Finite Element Method (FEM). Based on the electromagnetic field analyses, the saturation degree of stator iron core is analyzed under different armature currents. And the influences of HTS axial Magnetic Motive Force (MMF) on radial air-gap flux density, no-load back EMF, and electromagnetic torque are studied. The experiments on the prototype are performed. And the obtained conclusions are helpful for the further study on large capacity fully superconducting synchronous motor.

This paper presents the sensitivity analysis of the behavior of a synchronous machine using the winding functiontheory considering the effect of static air-gap eccentricity. The winding function theory as a method to calculate theinductances of synchronous machines from the geometry and the actual arranging of the windings is presented. Then,detailed numerical simulations are carried out to examine the impact of eccentricity on the steady state regimes. Theimportant role of static eccentricity and its links with various symmetrical and asymmetrical operating conditions arediscussed as well as its influence on the machine parameters and performance are investigated. Experimental andanalytical parameter results are presented for a 60 Hz, six-pole laboratory synchronous machine connected to aninfinite bus under various static eccentricity conditions.

In order to explore the dynamic behavior and motion law of motorized spindle under eccentric condition, a dynamic model of motorized spindle considering unbalanced magnetic pull under eccentric condition is established. The effect of gyroscopic moment is considered. The model is established by Lagrange method, and the model is simulated and analyzed. The law of rotor response change under different speed, unbalance and air gap changes is obtained. The simulation results show that the static eccentricity will increase the vibration of the motorized spindle. Under the same static eccentricity and mass eccentricity, the influence of static eccentricity on rotor decreases with the increase of rotating speed. Mass eccentricity is called the main influencing factor. In frequency domain analysis, when the static eccentricity occurs, the peak appears at 0Hz, which is the effect of unbalanced magnetic tension on vibration. With the increase of rotating speed, the frequency size of the peak value of fundamental frequency will also increase. The research results provide a theoretical basis for the in-depth analysis of the failure mechanism of rotating machinery.

The aim of this paper is to calculate the static eccentricity (SE) of a double rotor axial flux permanent magnet (AFPM) machine by using a general analytical model. The flux density in the air gap under healthy conditions is calculated firstly, where the axial and circumferential magnetic flux densities are obtained using a coupled solution of Maxwell’s equations and Schwarz-Christoffel (SC) mapping. The magnetic flux densities under SE conditions are calculated afterwards using a novel bilinear mapping. Some important electromagnetic parameters, e.g., back electromotive force (EMF), cogging torque and electromagnetic (EM) torque, are calculated for both SE and healthy conditions, and compared with the finite element (FE) model. As for the double rotor AFPM, SE does not contribute much effect on the back EMF and EM torque, while the cogging torque is increased. At each calculated section, FE models were built to validate the analytical model. The results show that the analytical predictions agree well with the FE results. Finally, the results of analytical model are verified via experimental results.

There are two main beneficial characteristics that doubly salient permanent magnet (PM) electrical machines present for aircraft applications: armature windings and PMs excitation sources placed on the stator side (maintenance and thermal management), and having a clear-cut rotor without PMs or excitation windings (vulnerable at high speeds due to associated centripetal mechanical stresses). Within this framework, a doubly salient permanent magnet (DSPM) generator was conceived by optimizing the stator size and rotor structure to minimize the torque ripple and maximize the root-mean-square (RMS) voltage value per turn of each generator phase. Firstly, a comparison between the 2D and 3D finite element method (FEM) models is made considering the results of 3D finite element analysis (FEA) as our benchmark in order to understand the accuracy of the 2D results against our benchmark model, the 3D one. A multi-objective design strategy based on a 2D FEA is made, it is set to have characteristics closest to optimal for a Boeing 767 turbine, that is, the necessary electromotive force for a required power of 90 kW at 3000 rpm, feeding a simplified Boeing 767 electrical power distribution system. The results show that the machine could not deliver the required power at 3000 rpm since the 2D FEA demonstrates that the 2D model gives optimistic results when compared with the 3D FEM model. However, with a 3D FEA of the machine feeding the aircraft load, it was seen that the machine’s efficiency is 92%, suggesting that this machine can be a plausible solution.

Magnetic gear is an alternative to mechanical gear, where the magnetic gear has the advantages of no noise, minimum vibration, no maintenance required, increased reliability, overload protection capability, no physical contact between gears, and the resulting torque density is still below the mechanical gear torque density. In this research, the variation of the number of poles and air gap in the amount of torque density produced was carried out. The permanent magnet material used is Neodymium type with a gear ratio of 1:2. In the variation of the number of poles used by pairs of 4 and 8 poles, 8 and 16 poles, 10 and 20 poles, and 12 and 24 poles, in the variation of the air gap used, namely 1 mm, 1.2 mm, 1.3 mm, 1.4 mm and 1.5 mm. Magnetic gear performance can be seen through analysis simulation with the 3D finite element method using Finite Elements Software. The type of simulation used is the magnetostatic analysis method at the processing stage and the transient analysis method at the post-processing stage. From the simulation results, it is concluded that the greater the number of poles, the greater the torque density produced, and the closer the air gap distance will result in a greater torque density. The effect of the number of poles on the torque density is more significant than the effect of the air gap.