那邦电站发电机主要部件有限元分析

为确保那邦电站高转速水轮发电机各主要部件结构的合理可靠性,采用CATIA三维设计软件对发电机定子机座、转子磁轭、磁极、上机架各主要核心受力部件建立几何模型,并用MSC.patran建立计算模型,根据发电机自身的受力特点确定各部件的工况及边界条件,运用有限元受力分析找出了各主要部件受力的薄弱点,使结构性能得以进一步优化。计算结果及实际运行情况表明,有限元计算给发电机各主要部件的结构设计及材料合理选用提供了很好的支持,保障了发电机长期安全稳定运行。     

Numerical Modeling of Thermoelectric Generators With Varing Material Properties in a Circuit Simulator

When a thermoelectric generator (TEG) and its external load circuitry are considered together as a system, the codesign and cooptimization of the electronics and the device are crucial in maximizing the system efficiency. In this paper, an accurate TEG model is proposed and implemented in a SPICE-compatible environment. This model of thermoelectric battery accounts for all temperature-dependent characteristics of the thermoelectric materials to include the nonlinear voltage, current, and electrothermal coupled effects. It is validated with simulation data from the recognized program ANSYS and experimental data from a real thermoelectric device, respectively. Within a common circuit simulator, the model can be easily connected to various electrical models of applied loads to predict and optimize the system performance.      

基于有限体积法的有压管道水锤计算

在水电站运行过程中,为了避免机组增减负荷产生的水锤威胁输水系统的安全,需要对有压管道中的水锤进行精确的模拟计算。基于有限体积法对有压管道水锤方程分别进行空间和时间尺度上的积分,并采用隐式的Crank-Nicolson格式对偏微分项进行处理,从而得到了具有二阶精度且无条件稳定的水锤方程离散格式。通过算例比较了该离散格式与特征线法的计算结果,结果表明,新推导的离散格式在计算有压管道水锤问题时具有较高的精度且稳定性较好。     

Improved Treatment of Anisotropic Scattering in Radiation Transfer Analysis Using the Finite Volume Method

Discretization of the integral anisotropic-scattering term in the equation of radiative transfer will result in two kinds of numerical errors: alterations in scattered energy and asymmetry factor. Though quadrature flexibility with large angular directions and further solid-angle splitting in the finite volume method (FVM) allow for reduction/minimization of these errors, computational efficiency is adversely impacted. A phase-function normalization technique to get rid of these errors is simpler and is applied to the three-dimensional (3-D) FVM for the first time to improve anisotropic radiation transfer computation accuracy and efficiency. FVM results are compared to Monte Carlo and discrete-ordinates method predictions of radiative heat transfer in a cubic enclosure housing a highly anisotropic participating medium. It is found that the FVM results generated using the normalization technique conform accurately to the results of the other two methods with little impact on computational efficiency.     

Modal Analysis of Grid-Connected Doubly Fed Induction Generators

This paper presents the modal analysis of a grid-connected doubly fed induction generator (DFIG). The change in modal properties for different system parameters, operating points, and grid strengths are computed and observed. The results offer a better understanding of the DFIG intrinsic dynamics, which can also be useful for control design and model justification.     

A High Order Control Volume Finite Element Method for Transient Heat Conduction Analysis of Multilayer Functionally Graded Materials with Mixed Grids

This paper describes a new two-dimensional(2-D) control volume finite element method(CV-FEM) for transient heat conduction in multilayer functionally graded materials(FGMs). To deal with the mixed-grid problem, 9-node quadrilateral grids and 6-node triangular grids are used. The unknown temperature and material properties are stored at the node. By using quadratic triangular grids and quadratic quadrilateral grids, the present method offers greater geometric flexibility and the potential for hig...     

两级热电热机的有限时间热力学分析

建立了考虑外部传热影响的两级半导体热电热机模型,用有限时间热力学对牛顿传热规律下两级半导体热电热机的性能进行分析,导出了功率、效率与工作电流的一般关系式,得到了两侧换热器的最优面积分配和热电单元数的最优分配,并分析了多种因素对其性能的影响。     

炉内辐射换热过程的有限体积法

简要分析了含吸收散射性介质的三维空腔内辐射传递方程的有限体积法求解过程,应用该方法对四角切圆炉膛内的辐射换热过程进行模拟计算,得出了炉膛内温度分布,并将计算结果与实测值进行了比较。通过数值计算表明：有限体积法计算速度快,对不规则边界适应性强,具有很高的工程可用性。     

温差发电器应用于火力发电厂的分析

火力发电厂用锅炉吸收热能发电,而锅炉这一特殊结构部件既可以为热电效应为基础的温差发电器提供热源,也可以为其提供冷源,这为温差发电器应用于火力发电厂创造了条件。本文对应用温差发电器的可能性以及应用后火力发电厂的效率进行了分析,结论是可以提高火力发电厂效率,提出了锅炉各个温度区域如何应用热电器件的方法,并对在锅炉中应用温差发电器应该考虑的问题进行了分析。     

热电发电机驱动热电热泵联合循环热力学分析

建立了新型的热电发电机驱动热电热泵联合循环模型,基于非平衡热力学理论,对装置性能进行分析,导出了供热率、无量纲供热率和供热系数与热电单元比等参数的解析式,研究了该型装置最大供热率和最大供热系数对应的最优工作电流和最优热电单元分配,分析了发电机高温热源温度、热泵供热空间温度等对装置供热率、供热系数、最优工作电流和最优热电单元分配的影响,并给出了不同发电机热源温度下,供热系数与无量纲供热率的关系曲线.     

330 MW发电机无刷励磁系统运行分析

从运行人员的角度出发,紧密结合现场实际,论述了蒲电二期汽轮发电机组无刷励磁系统及其附属系统的工作原理。分析比较了发电机无刷励磁系统与传统励磁系统,结果表明,发电机无刷励磁系统运行可靠性高,技术和经济性能优越。提出了蒲电二期发电机自并励励磁系统在设计方面存在的问题：监测旋转二极管运行情况的霍尔效应传感器易发生故障;发电机的励磁电流、励磁电压难以监视等。     

水轮发电机可靠性参数统计及分析

通过对水轮发电机停运工况统计出的无故障运行时间数据，利用数理统计的方法进行分析，得出了水轮发电机的故障率为指数分布，得到了所分析水轮发电机的可靠度函数、不可靠度函数及故障率等可靠性指标。     

组合式活塞的一种实体有限元模型与分析

提出一种组合式活塞的实体有限元模型，采用自由度耦合方法处理裙部与活塞头之间的接触联结问题。并分析了计算了一新设计的内燃机车活塞的温度场，以及气体压力，往复惯性力和热载荷共同作用下的活塞综合变形与应力。计算结果表明，活塞的综合变形与应力并不呈轴对称分布，活塞顶部存在较大的局部弯曲机械应力。     

Stress Evolution and Thermal Shock Computation Using the Finite Volume Method

This work presents a novel numerical approach to thermal shock and transient thermal stress distribution based on the Finite Volume method. A unified approach was developed based upon the coupling between a three-dimension thermal solution and a linear thermo-elastic, multi-layered plane stress approximation. Temperature distributions were compared to analytical solutions for a flat plate and to experimental results using a temperature-dependent heat transfer coefficient. The numerical results were assessed against three analytical methods: Timoshenko and Goodier, Lu and Fleck, and Collin and Rowcliffe. This work demonstrates that the FVM provides also accurate results for thermal stress distributions in solids.     

多热电联产机组建模及热电动态耦合特性分析

为解决多热电联产机组发电与供热、供汽负荷存在强耦合、对象兼有大惯性大迟延、系统时变非线性等多种复杂特性而难以控制的问题,采用机理分析方法建立某300 MW机组各主要动态环节的能量平衡微分方程,并依据设计和运行数据确定模型参数,建立了适用于全负荷工况的动态模型,并将机组实际输入信号引入模型,通过对比模型输出与对象实际输出...     

Thermodynamic Analysis and Experimental Research of Water-Cooled Small Space Thermoelectric Air-Conditioner

This paper aims to find a more general analysis method for the refrigeration performance,and to design a high efficiency modular cooling structure of water-cool...     

用有限容积法对YC6112ZLQ型柴油机进行模拟计算

本文针对玉柴机器股份有限公司生产的YC6112ZLQ型柴油机进行了一系列的试验研究,同时利用有限容积法对国产P7加强泵与YC6112ZLQ-180型柴油机配机后的柴油机工作过程进行了模拟计算。计算结果与实测数据对比显示,由于采用了有限容积法,提高了排气系统的计算精度,使得相应的整台柴油机的模拟计算精度也得以提高。     

Contributions to the Steady State Analysis of Wind-Turbine Driver Self-Excited Induction Generators

The paper makes the following three contributions: First, it presents a digital computer method of predicting the steady state performance of a self-excited induction generator for given spped, capacitance and load conditions along with results of validation studies on a laboratory machine. Secondly, a procedure is presented to check whether the operating point of a given uncontrolled wind-turbine driven self-excited induction generator set on load is a satisfactory point. Details of the resulting capability chart are discussed by application to a specific case. Finally, an experimental method of simulating wind-turbine drive characteristics is presented along with details of implementation of a laboratory set-up involving a d.c. dynamometer coupled to an induction generator.     

内燃机零部件有限元分析的研究现状与展望

有限元法在内燃机零部件设计中的应用，极大地提高了内燃机零部件的设计水平，缩短了设计周期，提高了设计的可靠性，推动了内燃机工业的发展。论述了有限元技术在内燃机曲轴和连杆等零部件设计中的应用现状及最新发展，并讨论分析了发展趋势。     

伦敦地铁的数值分析

本文用有限元方法模拟了伦敦地铁J.支线分部开挖的施工过程,对各开挖阶段的围岩稳定与喷层、衬砌内力做了分析、预测.其计算结果已被设计者所采用.