尾切叶片全叶栅气动特性的实验研究

在不同节距和冲角下，对具有尾切叶片的透平高压级转子全叶栅进行了静吹风。实验结果表明，无论在设计和变工况下，由于二次流损失的影响端壁附近的流量系数最小，这产实际最佳尾切尺寸小于理想最佳尾切尺寸的原因之一，但不是主要原因。主要原因是前列静子叶栅叶片尾切使尾流区加宽，这样的尾流进入转子流道引起流动严重恶化。     

透平叶片尾切对叶型损失和流量系数影响的实验研究

通过对运行透平机组叶栅的模型实验数据的分析，探讨了采用叶片轴向尾切在提高机组出力时最佳尾切尺寸的问题，实验表明，叶片尾切在增加叶栅喉宽提高流量的同时，增大了叶型损失并降低了流量系数，得出尾切尺寸的大小取决于流量系数与喉宽的来积的结论，同时还应考虑尾流宽度对下游叶栅的非定常影响。     

透平叶片尾切对叶型损失和流量系数影响的实验研究

通过对运行透平机组叶栅的模型实验数据的分析，探讨了采用叶片轴向尾切在提高机组出力时最佳尾切尺寸的问题，实验表明，叶片尾切在增加叶栅喉宽提高流量的同时，增大了叶型损失并降低了流量系数，得出尾切尺寸的大小取决于流量系数与喉宽的乘积的结论，同时还应考虑尾流宽度对下流叶栅的非定常影响。     

改进铸铝模具 消除端环缩孔

我厂电机无风叶的铸铝转子存在端环缩孔质量问题。本文从铸铝转子生产工艺原理分析人手．认为铸铝转子的缩孔主要产生在转子的下端环内圈的中部位置，这个部位由于浇铸铝液冷却最慢，当周围组织冷却后，这部分才冷却，由于再得不到材料补缩，因此才产生凹陷——形成缩孔、缩印等缺陷。如何在模具结构设计、铸铝转子形状尺寸设计、铸铝工艺参数等方面进行改进，消除缩孔的产生，是我们要研究和探讨的问题。通过对国内相关厂家调访，结合我厂铸铝转子生产工艺进行比较，提出要研究和探讨的主要问题。本文此次主要对铸铝模具的结构设计提出改进意见，改进实施后，并进行实践试验，取得实践试验结果后，再确定下一步改进项目。此次主要改进：铸铝模浇口直径尺寸的改进：上模进水口高度尺寸改进；下模排气槽尺寸改进。铸铝模浇口直径尺寸的改进、排气槽和散热排气孔改进试验。     

无刷直流力矩电动机轴向随机振动分析

利用ANSYS Workbench有限元仿真平台,对无刷直流力矩电动机进行了轴向随机振动仿真分析。根据仿真分析结果,推断出引起无刷直流力矩电动机随机振动试验中定子轴向尺寸变大,安装在定、转子上的动、静试验光栅盘发生摩擦损坏的主要原因,为电机的结构优化提供了有效依据。     

双水内冷汽轮发电机转子线圈引水铜线断裂事故的分析

本文讨论了水冷电机转子引水线的受力情况,较全面地分析了引起引水线静、动应力的各种因素,文中指出:由于转子静挠度的影响,使引水线两端出现径向和轴向交变相对位移。在这两种相对位移的作用下,引水线产生较大的动应力。这乃是造成引水线疲劳断裂的主要原因。当转子运转时,由于离心力和径向浮起,使引水线出现很高的静应力;电机反复起动、停机使引水线产生低周疲劳,此二者对于引水线的断裂破坏也都起着一定的作用。文中还推导出径向和轴向相对位移的计算公式,论述了转子引水线静、动应力计算方法的基本原理;提出了“z”型引水铜线静、动应力计算公式。对双水内冷20万千瓦汽轮发电机上断裂的引水线的静、动应力进行了具体计算,其结果同实际断裂情况基本相符。     

电机冲片常见超差现象分析

定、转子冲片是电机的重要组成部分，它质量的好坏直接影响着电机性能的优劣。而由于影响定、转子冲片质量主要有冲压工艺模具结构的合理程序（主要是间隙大小的取值）、冲床的正常状态（特别是滑块间隙）、硅钢片的质量以及冲压操作的规范性等因素，使得定、转子冲片尤其是定子冲片易造成超差，针对超差产生的原因分析如下：(1)同轴度同轴度超差是指冲片内、外圆不同心，槽形单边。定子片同轴度超差可造成定子片叠压后定子铁心外圆参次不齐，尺寸超差；转子片槽形单边，则造成铸铝转子金加工后露铝条。产生原因主要是目前电机行业普遍采用…     

给水泵密封结构对转子可靠性的影响

给水泵的很多事故都与其密封结构有关。文章论述了给水泵密封结构对转子动稳定和动静部件咬合的影响；通过对水动力，转子涡动和泵壳温差的分析，阐述了密封间隙及密封面沟槽尺寸对其的影响，阻涡流槽可以减少密封间隙液体的切向驱动力，降低转子的涡动力向力；提出了提高转子动稳定和防止咬合的措施。     

电机定转子偏心磨擦的判断与偏心量的测算

定转子磨擦是电机运行的常见缺陷,在排除了转子轴弯及定转子间隙过小的前提下,一般可通过调整端盖偏心来解决。具体方法如下：（1）检查摩擦部位,测量径向间隙,判断磨擦原因。常见现象及原因分析如下：（2）在判明转子相对走子有偏心后,沿间隙差距最大的方向测量图示各尺寸。测量时应注意排除转子自身径向跳动的影响,可确定转子上某一点测量尺寸见、b;后,旋转180”测量对称点尺寸地、bu;据此可确定A、B点的偏心量人、人及方向,再根据轴向尺寸L、l;、l。换算出瑞盖轴孔的偏心量即可。换算公式如下：①久、八方向平行时,A、B、0…     

试析三相异步电动机振动大的原因

在电机制造过程中,由于机械、电气等方面故障不同程度引起电机振动超过正常值。 转子动平衡试验不合格,是造成电机振动过大的常见原因。这种原因对高速电机及转子仅做静平衡的电机尤其关键。由转子不平衡离心力惯     

MODIFIED ASYNCHRONOUS CASCADE MACHINE SYSTEM

ABSTRACT

The modelling of the modified asynchronous cascade machine system is done in order to study the features of such system under field-oriented frame of reference. The modified machine system has two stator windings and two sections of rotor winding on the same shaft One of the stator windings is connected to the ac network while the other winding is connected to an inverter capable of controlling power flow in both directions. This system can be operated in a wide speed range and both sections of the rotor winding can produce useful torque.     

单支撑旋转超声电机及其速度特性研究

分析了双轴承支撑超声电机的加工和装配误差所造成的定、转子接触界面沿圆周方向压力不均衡的现象,它是造成电机转速波动的主要原因之一。在此基础上,提出了一种单轴承支撑附加调心结构的新方案,通过实现接触界面的压力自平衡,来达到提高电机转速稳定性,同时减小体积、减轻质量的目的。实验结果表明,在电机输出力矩、速度等主要性能指标与原结构电机相比没有下降的前提下,新方案电机的空载转速波动率降低了约40%,质量降低约14%,厚度减小了27.3%。     

多级压气机动叶片时序效应数值研究

对某型燃气轮机中间三级轴流压气机流场进行了非定常数值模拟,研究第二级动叶时序(CLOCKING)效应对中间级各列叶片气动负荷的影响。计算过程采用基于谐函数(Harmonic)的频域变化方法对全三维Navier-Stokes(N-S)方程进行求解。通过对各列叶片非定常气动负荷进行时域和频域分析,指出转子叶片中间级动叶R2处于不同的CLOCKING位置时,会引起R2叶片本身以及下游中间级静叶S2气流激振力显著变化。在CLK0(各列动叶片在周向上安装位置相同)位置,中间级静叶片在部分时刻内受力与常规方向相反,且气动力和力矩波动幅度最大。在CLK2(动叶片在周向上错开1/2节距安装)位置上,R2叶片和S2叶片气动负荷的稳定性都得到改善。静叶S2气动力、气动力矩波动幅值明显较其他位置小,且方向的改变次数也较小。同时,S2对其上下游动叶一倍通过频率的响应也最小,因此具有比较稳定的气动负荷。     

Studying the development of asynchronous rolling of the rotor over the stator with the turbine unit protection systems having different response times

The possibility to stabilize the developing asynchronous rolling of the rotor over the stator under the conditions of power unit protections coming in action with different response times is considered. Asynchronous rolling of the rotor over the stator may develop when the rotating rotor comes in contact with the stator at high amplitudes of vibration caused by an abrupt loss of rotor balancing, by forced or self-excited vibration of the rotor, and by other factors. The danger of asynchronous rolling is connected with almost instantaneous development of self-excited vibration of the rotor when it comes in contact with the stator and with the rotor vibration amplitudes and forces of interaction between the rotor and stator dangerous for the turbine unit integrity. It is assumed that the turbine unit protection systems come in action after the arrival of signal of exceeding the permissible vibration level and produce commands to disconnect the generator from the grid, and to stop the supply of working fluid into the flow path, due to which an accelerating torque ceases to act on the turbine unit shaft. The protection system response speed is determined by a certain time t = ABtime that is taken for its components to come in action from the commencement of the event (application of the signal) to closure of the stop valves. The time curves of the main rolling parameters as functions of the ABtime value are presented. It is shown that the response time of existing protection systems is not sufficient for efficiently damping the rolling phenomenon, although the use of an electrical protection system (with the response time equal to 0.40–0.45 s) may have a positive effect on stabilizing the vibration amplitudes to a certain extent during the rolling and on smoothing its dangerous consequences. The consequences of rotor rolling over the stator can be efficiently mitigated by increasing the energy losses in the rotor-stator system (especially in the stator) and by fulfilling the recommendations of the machinery unit catastrophe prevention system.     

全复式定子和转子落料模具的研究

介绍了电机全复式定子冲片和转子圆片一次冲压成型的落料工艺,通过阶梯冲实现定子内外圆、定子槽型、转子内外圆的分离。该工艺关键点在于转子凸凹模,其既是刃口又是卸料板,全部采用模具钢制造。整个冲裁过程仅需一道工序即可完成,生产效率大幅提高,节省了人力,降低了生产成本,提高了定子冲片精度。     

利用冷却介质优化设计的卧式电机

提出一种采用浸泡式蒸发冷却的电机结构优化方法。包括以下步骤:以相同电压等级和容量的风冷式电机为比照基准,将定子主绝缘层厚度相应地减少近一半,并将定子电流密度相应地增大;在上述定子主绝缘层厚度和定子电流密度的基础上,根据各参数不同取值的组合计算结果,获得各部件结构的最小形状数据;所述各参数包括气隙磁通密度、定子绕组的匝数、定子和转子的内径和外径以及定子槽和转子槽的高度和宽度。本优化设计充分发挥了浸泡式蒸发冷却技术的优势,在相同电压等级和容量下,电机及各主要部件外形尺寸大大减小,降低了制造成本。     

Specific features relating to the motion of a rotor with rubbing against the stator

Specific features relating to the motion of a rotor with rubbing against the stator and the rolling of a rotor over the stator are considered. Conditions under which rolling of the rotor over the stator occurs and the kinematic and force characteristics of this phenomenon are investigated. Simple analytical solutions are obtained for a model assuming that an absolutely rigid rotor and an absolutely rigid stator come in absolutely inelastic contact with each other, which allow one to get a clear idea about the roll-over phenomenon. An attempt is made on the basis of the proposed model to understand some striking features of the accident that occurred in the 300 MW power unit at the Kashira district power station in 2002.     

锥形转子电机定子单冲和定转子分切复合模设计

通过对锥形转子电机定子单冲、定转子分切两道工序的特点进行分析,给出了两道工序合二为一的复合模具设计,并在实际中得到应用。     

A control strategy for stand-alone wound rotor induction machine

A control strategy to regulate the frequency and voltage of a stand-alone wound rotor induction machine is presented. This strategy allows the machine to work as a generator in stand-alone systems (without grid connection) with variable rotor speed. A stator flux-oriented control is proposed using the rotor voltages as actuation variables. Two cascade control loops are used to regulate the stator flux and the rotor currents. A closed loop observer is designed to estimate the machine flux which is necessary to implement these control loops. The proposed control strategy is validated through simulations with satisfactory results.