共查询到20条相似文献,搜索用时 15 毫秒
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Lisiate Takau Pat Bodger 《能源与动力工程:英文版》2014,(6):1085-1092
This paper presents the modelling of transduction heaters using the TEC (transformer equivalent circuit) model and FEA (finite element analysis). Each model was used to simulate a set oftransduction heating experiments and the results compared. Analysis of the TEC calculated results suggested modification of three parameters: the secondary resistance, the core tube eddy current resistance and the core tube magnetizing reactance. The improved TEC model was then used to design, build and test a 6 kW transduction heater. The measured results are compared with calculated results from the TEC and FEA models. The TEC model accurately predicts the performance of the heater. 相似文献
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This paper proposes a numerical methodology for the prediction of the first three modes of vibration of an electric motor fixed on a rigid base. A deep literature review supported the production of four ad hoc prototypes that aided the development of the proposed approach. Tests carried out with the prototypes led to the procurement of the modal parameters be used to calibrate the numerical models, as well as the FRF (frequency response function) curves be used to validate the numerical solution. The validated model allowed structural changes to be then promoted on the prototypes, in order to make them more robust to variations in manufacturing and assembling processes. The mentioned adjustments and structural changes were accomplished by means of a process of structural optimization using Genetic Algorithm. The solution was developed based on the commercial finite element code ANSYS. The practical results obtained in this study show that a numerical model for modal analysis of an electric motor fixed on a rigid base with errors less than 3% for the first three modes of vibration can be achieved, allowing positive structural changes to be performed in the machine design that result in the minimization of manufacturing reworks associated with the dynamic behavior of the studied motor. 相似文献
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Transformers are normally designed and built for use at rated frequency and sinusoidal load current. A non-linear load on a transformer leads to harmonic power losses which cause increased operational costs and additional heating in transformer parts. It leads to higher losses, early fatigue of insulation, premature failure and reduction of the useful life of the transformer. To prevent these problems, the rated capacity of transformer which supplies harmonic loads must be reduced. In this work, a typical 50 kVA three-phase distribution transformer with real practical parameters is taken under non-linear loads generated due to domestic loads. The core losses is evaluated using the three dimensional model of the transformer developed in FEM (finite element method) program based on valid model of transformer under high harmonic conditions. And finally a relation associated with core losses and amplitude of high harmonic order are reviewed & analyzed and then a comparison is being carried out on the results obtained by different excitation current in transformer windings. 相似文献
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Bemd Schlegl Christian Scheinecker Andreas Marn Fritz Neumayer Mario Himmelreich Franz Heitmeir 《能源与动力工程:英文版》2013,(8):1496-1504
End windings of generators are excited to vibrations due to electromagnetic forces which can cause severe damage and noise. To avoid this, it is important to predict the natural frequencies and modes of the end windings with finite elements. Due to the complex structure and unknown boundary conditions, the conventionally calculation of stator end windings has been very difficult and time consuming up to now. This paper describes the development of a full parameterized modeling tool, which allows a quick calculation of natural frequencies during the design phase of the generator. To keep the computing time low, it is important to find a way to get exact calculation results without detailed modeling of all pans. Additionally, special attention was paid to the active part, which has been replaced by spring-damper elements, and the determination of their stiffness via experimental modal analysis combined with finite element calculations. 相似文献
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The results of the assessment of the influence of paper insulation on the discharge initiation in oil were presented in this paper. This assessment based on the results of performed experimental works and on the analysis of electrical field distribution. Both types of the studies were connected with the model HV (high voltage) electrode setups covered by paper and immersed in oil. Experimental works indicated that the source of "weak points" of paper-oil model electrode setup is oil, not the surface of metal or insulation wrapping. Such hypothesis, resulting mainly from the measured times to initiations of discharges developing from bare and insulated HV electrodes, was verified by the analysis of electrical field distribution performed on the basis of finite element method applied in the COMSOL Multiphysics software. This analysis confirmed preliminary the made hypothesis. Correlation with the most stressed oil volume law was also observed. 相似文献
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Carlos Frederico Mattos Schettino Guilherme Pennachin Sakamiti Joao Carlos Aguiar Gaspar Jflnior 《能源与动力工程:英文版》2014,(9):1583-1589
The present work aims to evaluate the increase in the number of spot welds in the 16 × 16 type fuel assembly structure that connects guide thimbles and spacer grids, in order to provide a proper joint for this connection. This new and improved process can provide more stiffness to the whole structure, since the number of spots raised from four to eight. A 3-D geometric model of a guide thimble section was generated in a CAD (computer aided design) program (SolidWorks). After that, the geometric model was imported to a CAE (computer aided engineering) program (ANSYS Mechanical APDL, Release 14.0), where the finite element model was built, considering the guide thimble geometry assembled with the spacer grid through the welded connections. Boundaries conditions were implemented in the model in order to simulate the correct physical behavior due to the operation of the fuel assembly inside the reactor. The analysis covered specific loads and displacements acting on the entire structure. The method used to solve this finite element analysis was a linear static simulation in order to perform the connection between a spacer grid cell and a guide thimble section. Hence, four models was evaluated, differing on the spot weld number in the spacer grid and guide thimble connection. The rotational stiffness results of each model were compared. The results acquired from four and eight spot weld were validated with physical test results. The behavior of the structure under the acting force/displacement and the related results of the analysis, mainly the stiffness, were satisfied. The results of this analysis were used to prove that the increasing spot welds number is an improvement in the dimensional stability when submitted to loads and displacements required on the fuel assembly design. This analysis aid to get more information of extreme importance such as, the pursuance to develop better manufacturing process and to improve the fuel assembly performance due to the increasing of the bum-up. 相似文献
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It is well known that a SMPS (switched-mode power supply) is easy to produce strong EMI (electromagnetic interference) and fails in EMC (electromagnetic compatibility) test for its far field radiation exceeds the limits between 30-200 MHz. Based on asymmetry line antenna theory, a novel far field CM (common mode) radiation model, including an equivalent driving source, radiation structure and some key influence factors, is identified and built up for a small flyback power supply. Radiation characteristics of this model are predicted by using Ansoft HFSS software and the model effectiveness is verified by experiment. In the end, the radiation role of some key factors, such as the length of output cable, common mode impedance of AC grid, layout of cable and reflected ground, are studied using simulation in detail. 相似文献
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Fatigue verification of Class 1 nuclear power piping according to ASME Boiler and Pressure Vessel Code, Section III, NB-3600, which is often discussed in connection to power uprate and life-extension of aging reactors in recent years, is dealt with. Key parameters involved in the fatigue verification, e.g., the alternating stress intensity Salt, the penalty factor Ke and the cumulative damage factor U, and relevant computational procedures applicable for the assessment of low-cycle fatigue failure using strain-controlled data, are particularly addressed. A so-called simplified elastic-plastic discontinuity analysis for alternative verification when fatigue requirements found unsatisfactory, and the procedures provided in NB-3600 for evaluating the alternating stress intensity S,j,, are reviewed in detail. An in-depth discussion is given to alternative procedures suggested earlier by the authors using nonlinear finite element analyses, which uses a nonlinear finite element analysis for directly determining the alternating stress, thus eliminating uncertainties resulted from the use of the penalty factor Ke. Using this alternative, unavoidable plastic strains can be correctly taken into account in a computationally affordable way, and the reliability of the verification will not be affected by uncertainties introduced in the simplified elastic-plastic analysis. 相似文献
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Through a great deal calculation, the design and simulation analysis of stator parametric and rotor electromagnetic system of 1000MW turbo-generator are performed by using Ansoft Maxwell Rmxprt12.1 software. Besides. the basic parameters of the generator, the geometry dimensions of the stator and rotor, type and sizes of the slots, coils and windings parameters and the way of windings connection are determined. The finite element model of electromagnetic systems of generator stator and rotor was constructed by Ansoft Maxwe112D3D 12.1, and the transient electromagnetic characteristics of generator was analyzed and simulated. The 3D geometric models of turbo-generator were established respectively by using PROE software, and the dynamic finite element model of generator structure was built by ANSYS workbench 11.0. In addition, the dynamic characteristics of stator iron core, stator frame were calculated respectively. The simulation calculation has shown that the structural parameters, material parameters, and the electromagnetic characteristics parameters for large turbogenerator that are put forward by this paper should be optimal. and the design plan and method suggested by this paper should be feasible. The paper provides an effective solution for the development of larger turbo-generator than 1000 MW. 相似文献
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Rongfu Li Haifei Zhu Tingting Wang 《能源与动力工程:英文版》2014,(5):882-889
With the rapid growth of the offshore wind industry, the innovative floating offshore wind turbine is chosen as the most feasible device to harvest the vast wind energy in deep water area. However there is no practical design guide for the floating wind turbine especially the floating foundation. In this paper, based on the investigation on the worldwide floating wind turbine and current available expertise on floating platforms accumulated in offshore O/G (oil and gas) industry, an integrated design methodology is presented according to the specialized characteristics of wind turbine, including the type selection of foundation and mooring system, design standard, design procedure, design conditions, key technologies involved. Finally a semi-submersible floating foundation is designed to support certain megawatt-rating wind turbine of Goldwind and also performance analysis and code checks are performed to validate the design. The design method of the floating foundation provided in this paper is proved feasible and can be adopted in practical engineering design. 相似文献
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This paper presents an approach that utilizes the recently developed tools for analyzing wind blade properties resulting from geometric shape and geographical site characteristics to find possible blade design improvements. A set of blade shapes with a certain deviation of chord distribution from the initial geometry was investigated for WindPACT 1.5 MW turbine. The results showed that the original blade geometry can be improved based on individual site wind characteristics, giving better aerodynamic efficiency and reduced cost. 相似文献
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水布垭大坝面板在强地震作用下的非线性有限元分析 总被引:1,自引:1,他引:0
采用非线性动态显式有限元方法,对清江水布垭面板堆石坝在地震作用下的动态响应进行了计算分析,指出了混凝土面板在地震波作用下的应力水平和应力分布特点,预测了混凝土面板在地震发生后的结构完整性,计算经果表明,地震波作用下该坝混凝土面板强度满足设计安全要求。 相似文献
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微震监测技术是一种煤矿地球物理法,它可以有效监测矿井物理场岩体的动态变化。候村煤矿煤层赋存为-1200^-500 m,深部开采导致采场内矿山压力显现明显,微震监测技术的应用为及时预测预报矿山压力分布情况和集中程度提供了重要依据。介绍了微震监测技术的概念及特点,然后结合SOS微震监测技术在深部开采矿井的应用情况,总结分析了岩层运动的普遍规律,最后对微震监测技术在矿井深部开采的探索应用进行展望。 相似文献
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为研究复杂层状坝基的混凝土重力坝非溢流坝段的抗震性能,采用ADINA程序建立非线性有限元分析模型,以接触单元模拟缓倾角的软弱结构面,以concrete本构模型模拟混凝土材料在地震中的开裂、压碎动态特性,以Mohr-Coulomb本构模型模拟地基岩体材料在地震中的塑性屈服特性,分析了坝体位移、应力、接触面状态及极限抗震能力,研究了非溢流坝段在不同概率等级地震作用下的地震响应与破坏模式,并对复杂层状坝基重力坝的安全性能进行整体评价。结果表明,复杂层状地基结构的重力坝在地震中层间接触面能够产生一定滑移,但对坝体的应力和极限抗震能力影响不大。 相似文献
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An attempt has been made to develop a simple, reliable and cost-effective device for measuring the dynamic crack propagation velocity in a nuclear pressure vessel steel (SA516 gr. 70). The experimental method is described and a simple digital approach is proposed. The experimentally determined dynamic crack velocity has been utilized to obtain elastic dynamic stress intensity factors by INSAMCR (a two-dimensional dynamic finite element code which is a modified version of SAMCR developed by Dr Schwartz at the University of Maryland). A relationship between instantaneous crack tip velocities and dynamic stress intensity factors for pressure vessel steels is estimated using dynamic crack propagation velocities determined by a proposed measuring device. The relationship between the dynamic stress intensity factor and time history and the dynamic arrest toughness for each test are obtained using the generation mode dynamic finite element analysis. A function ƒ(å) = 1·356 − 2·672å + 6·494å2 − 4·539å3 + 1·461å4 is suggested which may be useful to predict the relationship between the dynamic fracture toughness (K(å)) and the dynamic crack arrest toughness (KIa) for SA516 gr. 70 steel (say K(å) = KIa ƒ(å) where å is the dynamic crack propagation velocity). 相似文献