scholarly journals AC loss simulation in a HTS 3-Phase 1 MVA transformer using H formulation

2021 ◽  
Author(s):  
W Song ◽  
Zhenan Jiang ◽  
X Zhang ◽  
M Staines ◽  
Rodney Badcock ◽  
...  
Keyword(s):  
Numerical Method ◽  
Low Voltage ◽  
Magnetic Energy ◽  
Single Layer ◽  
Ac Loss ◽  
Experimental Result ◽  
Radial Magnetic Field ◽  
Numerical Result ◽  
Double Pancake ◽  
H Formulation

One of critical issues for HTS transformers is achieving sufficiently low AC loss in the windings. Therefore, accurate prediction of AC loss is critical for the HTS transformer applications. In this work, we present AC loss simulation results employing the H-formulation for a 1 MVA 3-Phase HTS transformer. The high voltage (HV) windings are composed of 24 double pancakes per phase wound with 4 mm – wide YBCO wire. Each double pancake coil has 38 ¼ turns. The low voltage (LV) windings are 20 turn single-layer solenoid windings wound with 15/5 (15 strands of 5 mm width) Roebel cable per phase. The numerical method was first verified by comparing the numerical and experimental AC loss results for two coil assemblies composed of two and six double pancake coils (DPCs). The numerical AC loss calculated for the transformer was compared with the measured AC loss as well as the numerical result obtained using the minimum magnetic energy variation (MMEV) method. The numerical AC loss result in this work and experimental result as well as the numerical result using MMEV at the rated current agree to within 20%. Further simulations were carried out to explore the dependence of the AC loss on the gap between the turns of the LV winding. The minimum AC loss at rated current in the 1 MVA HTS transformer appears when the gap between turns is approximately 2.1 mm turn gap in the LV winding. This is due to the change of relative heights between the HV and LV windings which results in optimal radial magnetic field cancellation. The same numerical method can be applied to calculate AC loss in larger rating HTS transformers. © This manuscript version is made available under the CC-BY-NC-ND 4.0 license https://creativecommons.org/licenses/by-nc-nd/4.0/

scholarly journals AC loss simulation in a HTS 3-Phase 1 MVA transformer using H formulation

2021 ◽  
Author(s):  
W Song ◽  
Zhenan Jiang ◽  
X Zhang ◽  
M Staines ◽  
Rodney Badcock ◽  
...  
Keyword(s):  
Numerical Method ◽  
Low Voltage ◽  
Magnetic Energy ◽  
Single Layer ◽  
Ac Loss ◽  
Experimental Result ◽  
Radial Magnetic Field ◽  
Numerical Result ◽  
Double Pancake ◽  
H Formulation

One of critical issues for HTS transformers is achieving sufficiently low AC loss in the windings. Therefore, accurate prediction of AC loss is critical for the HTS transformer applications. In this work, we present AC loss simulation results employing the H-formulation for a 1 MVA 3-Phase HTS transformer. The high voltage (HV) windings are composed of 24 double pancakes per phase wound with 4 mm – wide YBCO wire. Each double pancake coil has 38 ¼ turns. The low voltage (LV) windings are 20 turn single-layer solenoid windings wound with 15/5 (15 strands of 5 mm width) Roebel cable per phase. The numerical method was first verified by comparing the numerical and experimental AC loss results for two coil assemblies composed of two and six double pancake coils (DPCs). The numerical AC loss calculated for the transformer was compared with the measured AC loss as well as the numerical result obtained using the minimum magnetic energy variation (MMEV) method. The numerical AC loss result in this work and experimental result as well as the numerical result using MMEV at the rated current agree to within 20%. Further simulations were carried out to explore the dependence of the AC loss on the gap between the turns of the LV winding. The minimum AC loss at rated current in the 1 MVA HTS transformer appears when the gap between turns is approximately 2.1 mm turn gap in the LV winding. This is due to the change of relative heights between the HV and LV windings which results in optimal radial magnetic field cancellation. The same numerical method can be applied to calculate AC loss in larger rating HTS transformers. © This manuscript version is made available under the CC-BY-NC-ND 4.0 license https://creativecommons.org/licenses/by-nc-nd/4.0/

Study on the AC Loss Reduction of REBCO Double Pancake Coil

2018 ◽  
Vol 28 (8) ◽  
pp. 1-6 ◽  
Author(s):  
Guole Liu ◽  
Guomin Zhang ◽  
Liwei Jing ◽  
Liwang Ai ◽  
Hui Yu ◽  
...  
Keyword(s):  
Ac Loss ◽  
Loss Reduction ◽  
Pancake Coil ◽  
Double Pancake

Prediction of Ridging by 3-Dimensional Texture in Ferritic Stainless Steels

2014 ◽  
Vol 622-623 ◽  
pp. 72-76
Author(s):  
Yang Jin Chung ◽  
Deok Chan Ahn ◽  
Frédéric Barlat ◽  
Myoung Gyu Lee
Keyword(s):  
Crystal Plasticity ◽  
Stainless Steels ◽  
Rolling Direction ◽  
Single Layer ◽  
Experimental Result ◽  
Dimensional Structure ◽  
Ferritic Stainless Steels ◽  
3 Dimensional ◽  
Crystal Plasticity Fem ◽  
Constitutive Parameters

Experimental and numerical investigations of the ridging in ferritic stainless steels were presented in this paper. Two kinds of ferritic stainless steels exhibiting different levels of ridging were selected as model materials. The measured roughness of the uniaxially elongated specimens up to 15% in rolling direction (RD) was compared to the prediction using a rate-dependent crystal plasticity FEM (CPFEM). Initial textures of the two materials on 5 equi-spaced sequential RD planes were obtained by EBSD measurement. The initial textures were utilized as input data for the constitutive parameters of the crystal plasticity. Measured respective single planar textures were collected all together so that the 5-layer textures complete 3-dimensional structure and they were mapped onto the FE mesh. Ridging profiles predicted by the CPFEM using both every single layer texture and multilayer texture were compared to the experimental results. Predicted ridging profile of a material exhibiting weak ridging by using 5-layer EBSD mapping was in good agreement with the experimental result. On the other hand, prediction by using only single layer texture was efficient to estimate the ridging in a material exhibiting severe ridging due to the elongated cluster of analogous orientations along RD.

Numerical Simulation of Cutting Force in High Speed Machining of Inconel 718

2020 ◽  
Vol 856 ◽  
pp. 43-49
Author(s):  
Santosh Kumar Tamang ◽  
Nabam Teyi ◽  
Rinchin Tashi Tsumkhapa
Keyword(s):  
Cutting Force ◽  
Inconel 718 ◽  
High Speed ◽  
Experimental Results ◽  
Machining Process ◽  
Experimental Result ◽  
Work Piece ◽  
High Speed Machining ◽  
Numerical Result ◽  
3D Software

Machining is one of the major manufacturing processes that converts a raw work piece of arbitrary size into a finished product of definite shape of predetermined size by suitably controlling the relative motion between the tool and the work. Lately, machining process is shifting towards high speed machining (HSM) from conventional machining to improve and efficiently increase production, and towards dry machining from excessive coolant used wet machining to improve economy of production. And the tools used are mostly hardened alloys to facilitate HSM. The work piece materials are continually improving their properties by emergence and development of newer and high resistive super alloys (HRSA). In this paper an attempt has been made to validate an experimental result of cutting force obtained by performing HSM on an HRSA Inconel 718, by comparing it with the numerical result obtained by simulating the same setting using DEFORM 3D software. Based on the comparison it is found that the simulated results exhibit close proximity with the experimental results validating the experimental results and the effectiveness of the software.

scholarly journals Analysis of AC Transport Loss in Conductor on Round Core Cables

2021 ◽  
Author(s):  
Jiabin Yang ◽  
Chao Li ◽  
Mengyuan Tian ◽  
Shuyu Liu ◽  
Boyang Shen ◽  
...  
Keyword(s):  
Eddy Current ◽  
Complex Geometry ◽  
Layer Structure ◽  
Single Layer ◽  
Element Model ◽  
Structure Design ◽  
Ac Loss ◽  
Shielding Effect ◽  
Transport Loss ◽  
Electro Magnetic

AbstractThe conductor on round core (CORC) cable wound with second-generation high-temperature superconducting (HTS) tapes is a promising cable candidate with superiority in current capacity and mechanical strength. The composing superconductors and the former are tightly assembled, resulting in a strong electro-magnetic interaction between them. Correspondingly, the AC loss is influenced by the cable structure. In this paper, a 3D finite-element model of the CORC cable is first built, and it includes the complex geometry, the angular dependence of critical current and the periodic settings. The modelling is verified by the measurements conducted for the transport loss of a two-layer CORC cable. Subsequently, the simulated results show that the primary transport loss shifts from the former to the superconductors as the current increases. Meanwhile, the loss exhibited in the outer layer is larger than that of the inner layer, which is caused by the shielding effect among layers and the former. This also leads to the current inhomogeneity in CORC cables. In contrast with the two-layer case, the simulated single-layer structure indicates stronger frequency dependence because the eddy current loss in the copper former is always dominant without the cancellation of the opposite-wound layers. The core eddy current of the single structure is denser on the outer surface. Finally, the AC transport losses among a straight HTS tape, a two-layer cable and a single-layer cable are compared. The two-layer structure is confirmed to minimise the loss, meaning an even-numbered arrangement makes better use of the cable space and superconducting materials. Having illustrated the electro-magnetic behaviour inside the CORC cable, this work is an essential reference for the structure design of CORC cables.

scholarly journals Numerical Investigation of Tip-Vortex Cavitation Noise of an Elliptic Wing Using Coupled Eulerian-Lagrangian Approaches

2020 ◽  
Vol 10 (17) ◽  
pp. 5897 ◽  
Author(s):  
Garam Ku ◽  
Cheolung Cheong ◽  
Hanshin Seol
Keyword(s):  
Flow Field ◽  
Numerical Method ◽  
Vortex Flow ◽  
Acoustic Pressure ◽  
Tip Vortex ◽  
Experimental Result ◽  
Cavitation Noise ◽  
Navier Stokes Equation ◽  
Tip Vortex Cavitation ◽  
Cavitation Inception

In this study, a numerical methodology is developed to investigate the tip-vortex cavitation of NACA16-020 wings and their flow noise. The numerical method consists of a sequential one-way coupled application of Eulerian and Lagrangian approaches. First, the Eulerian method based on Reynolds-averaged Navier–Stokes equation is applied to predict the single-phase flow field around the wing, with particular emphasis on capturing high-resolution tip-vortex flow structures. Subsequently, the tip-vortex flow field is regenerated by applying the Scully vortex model. Secondly, the Lagrangian approach is applied to predict the tip-vortex cavitation inception and noise of the wing. The initial nuclei are distributed upstream of the wing. The subsequent time-varying size and position of each nucleus are traced by solving spherically symmetric bubble dynamics equations for the nuclei in combination with the flow field predicted from the Eulerian approach. The acoustic pressure at the observer position is computed by modelling each bubble as a point source. The numerical results of the acoustic pressure spectrum are best matched to the measured results when the nuclei number density of freshwater is used. Finally, the current numerical method is applied to the flows of various cavitation numbers. The results reveal that the cavitation inception determined by the predicted acoustic pressure spectrum well matched the experimental result.

FLIPPED VOLTAGE FOLLOWER ANALOG NONLINEAR CIRCUITS

2012 ◽  
Vol 21 (03) ◽  
pp. 1250024 ◽  
Author(s):  
CHAIWAT SAKUL ◽  
KOBCHAI DEJHAN
Keyword(s):  
Relative Error ◽  
Low Voltage ◽  
Harmonic Distortion ◽  
Input Voltage ◽  
Experimental Result ◽  
Voltage Range ◽  
Flipped Voltage Follower ◽  
Voltage Follower ◽  
Power Dispersion ◽  
Four Quadrant

This paper describes squaring and square-rooting circuits operable on low voltage supplies, with their application proposed hereby as vector-summation and four-quadrant multiplier circuits. These circuits make use of a flipped voltage follower (FVF) as fundamental circuit. A detail classification of basic topologies derived from the FVF is given. The proposed circuits have simple structure, wide input range and low power consumption as well as small number of devices. All circuits are also examined and supported by a set of simulations with PSpice program. The circuits can operate at power supply of ±0.7 volts, the input voltage range of the squaring circuit is ±0.8 volts with 1.59% relative error and 1.78 μW power dispersion, the input current of the square-rooting circuit is about 50 μA with 0.55% relative error and 1.4 μW power dispersion and the vector-summation circuit have linearity error of 0.23% and 2.92 μW power dispersion. As in four-quadrant multiplier circuit, the total harmonic distortion of the multiplier is less than 1.2% for 0.8 VP-P input signal at 1 MHz fundamental frequency. Experimental result is carried out to confirm the operation by using commercial CMOS transistor arrays (CD4007). These circuits are highly expected to be effective in further application of the low voltage analog signal processing.

Acoustic Radiation by Point- or Line-Excited Laminated Plates

2000 ◽  
Vol 122 (3) ◽  
pp. 189-195 ◽  
Author(s):  
Y. F. Hwang ◽  
M. Kim ◽  
P. J. Zoccola
Keyword(s):  
Elasticity Theory ◽  
Sandwich Plate ◽  
Acoustic Radiation ◽  
Single Layer ◽  
Laminated Plates ◽  
Steel Plates ◽  
Numerical Result ◽  
Substantial Error ◽  
Theory Solution ◽  
Equal Thickness

This paper presents an elasticity theory solution for computation of acoustic radiation by a point- or line-excited fluid-loaded laminated plate, which may consist of a stack of an arbitrary number of different isotropic material layers. A one-side water-loaded three-layer sandwich plate, which consists of a hard rubber core sandwiched between two steel plates of equal thickness, was used as an example of the laminated plates. The approximated equivalent sandwich plate solutions were compared with the elasticity theory solutions. These results show that the approximated solutions are, as expected, valid only at frequencies much lower than the coincidence frequency. The numerical result also shows that, even at about one-tenth of the coincidence frequency, the approximated solutions suffer substantial error. The differences between the dry-side- and the wet-side-excited radiated fields of a single-layer uniform plate and a sandwich plate were investigated and compared, and found to be significantly different at frequencies above the coincidence frequency. [S0739-3717(00)01803-1]

Numerical Method for Simulating High Pressure CO2 Flows With Nonequilibrium Condensation

2018 ◽  
Author(s):  
Takashi Furusawa ◽  
Hironori Miyazawa ◽  
Shota Moriguchi ◽  
Satoru Yamamoto
Keyword(s):  
High Pressure ◽  
Numerical Method ◽  
Supercritical Co2 ◽  
Compressible Flows ◽  
Ideal Gas ◽  
Experimental Result ◽  
High Mass ◽  
Real Gas ◽  
High Pressure Co2 ◽  
Nonequilibrium Condensation

A numerical method for compressible flows with nonequilibrium condensation is reconstructed for simulating supercritical CO2 flows with nonequilibrium condensation under high pressure conditions. Thermophysical properties are interpolated from pressure-temperature look-up tables and density-internal energy look-up tables, which are generated using the polynomial equations in REFPROP. We employ the high pressure nonequilibrium condensation model in which the critical radius of a liquid droplet is modified by considering non-ideal gas. We simulate high pressure CO2 flows through a Laval nozzle, which was experimentally investigated by Lettieri et al. High-pressure CO2 passes through the nozzle, leading to a decrease in its pressure and temperature. It reaches the supercooled condition near the throat. Nucleation and the subsequent growth of droplets lead to an increase in the condensate mass fraction in the diverging area. The proposed method for real gas reproduced the peak of pressure distribution owing to the release of latent heat, whereas the numerical result assuming ideal gas is different from the experimental result. The nucleation region obtained using the present method is earlier and narrower than that in the case of ideal gas. The early and rapid nucleation leads to the high mass condensate rate at the outlet. These results show that considering the real gas effect and nonequilibrium condensation is crucial for developing the impeller of a compressor for the supercritical CO2 Brayton cycle.

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