1000MW汽轮发电机气隙流场的数值模拟

针对1 000MW系列水氢氢汽轮发电机,对发电机的气隙进行2D建模,对气隙及径向风道采用RNG k-ε湍流模型应用多重坐标系进行数值模拟,对发电机的气隙流场进行分析,并用模拟所得数据计算转子同一风道不同匝线棒中的气体流量得出流量分布规律,发现各线棒中气体流量较为均匀,为发电机的通风系统的设计提供依据.     

锅炉主汽管裂纹分析

介绍了锅炉主汽管发生裂纹、泄漏的情况,分析了裂纹产生的原因,对主汽管及疏水管的设计安装提出了改进意见。     

某发电机前联轴器联接结构应力分析与改进

某电厂600MW发电机前联轴器与轴联接结构采用了过盈和周向均布圆锥键的联接结构型式,在运行中出现了多处裂纹.本文采用线弹性有限元法对其进行了应力计算,计算考虑了多种载荷工况,计算结果准确地反映了裂纹产生的位置.文中分析了结构受力特点及应力分布规律,探讨了裂纹产生的原因,提出修改结构尺寸并作应力计算,结果表明尺寸改进后该结构体应力状况明显改善.本文可为此类联轴器与转轴联接结构强度设计提供参考.     

数值模拟在电站锅炉烟风道优化设计中的应用

分析讨论了电站锅炉烟风道的空气和烟气流动以及数值模拟方法在烟风道设计优化中的应用。燃烧系统风道设计能否保证空气分布平均一致,决定了燃烧器是否在设计条件下运行,从而决定了NOx排放水平和燃烧效率。SCR(Selective Catalytic Rednction)系统中烟道的设计能否确保进入SCR的烟气流场的均匀性,决定了SCR系统运行的效率和安全。数值模拟的方法能够分析烟风道内的流动情况,为优化改进烟风道的气流分配提供了设计和分析工具。通过实例说明数值模拟方法在锅炉风箱和SCR烟道改进优化实践中的应用。     

空冷汽轮发电机转子通风冷却系统的结构优化

以125 MW空冷汽轮发电机转子为研究对象,建立了转子径向通风系统的冷却介质流量分配离散模型,并应用该模型对125 MW空冷汽轮发电机转子径向通风系统进行了结构优化,分析了副槽结构、转子槽楔出风口面积对转子径向风道流量分配的影响.结果表明:在相同入口流量下,副槽截面积越大,径向风道流量偏差越小;转子槽楔出风口面积越小,径向风道流量偏差越小;采用变转子副槽结构及变转子槽楔出风口面积均可使径向风道流量偏差减小.     

汽油机活塞喷油缺口裂纹失效分析及设计改进

发动机的爆压及升功率达到一定数值时,考虑到热负荷对活塞的影响,需增加喷油冷却,提高活塞使用寿命,增强发动机可靠性。为了避免活塞与喷油嘴的干涉,需在活塞裙部增加喷油嘴避让缺口,增加缺口后,如果设计结构强度不足,活塞裙部椭圆度设计不合理,缺口处容易出现应力集中导致产生裂纹。本文通过典型实例对活塞喷油嘴避让缺口的裂纹失效进行了全面的分析,并提出设计改进的思路。改进设计后的活塞经发动机台架试验验证后,避让缺口部位没有出现开裂,试验通过,改进效果明显。     

单轴承主发电机试验安装方式改进

针对单轴承主发电机试验安装系统分析了主发电机振动速度值超差的原因,对原试验安装方式进行了结构改进,改进后的安装方式作为典型结构应用到其他单轴承主发电机的试验中.     

锦屏二级水电站发电机主保护设计

结合锦屏二级水电站水轮发电机的特性,通过对水轮发电机全面的内部短路分析计算、定量化的设计过程,完成了主保护配置方案的设计,保护方案性能优异.实现了水轮发电机保护无动作死区,而且对所有实际可能发生的内部故障有2种及以上不同原理的主保护灵敏动作,为大型水电站水轮发电机的安全运行提供了可靠保证.     

某发电机前联轴器与轴连接结构应力的有限元分析

某600MW发电机前联轴器与轴过盈连接结构体在运行期间出现了多处裂纹.采用线弹性有限元法,对该结构体进行了应力计算.计算考虑了多种过盈量和多种载荷,得到了该结构体相应工况下的应力分布,分析了此结构在运行状态下的受力特点及应力分布规律,探讨了产生裂纹的原因.可为此类联轴器与转轴连接结构的强度设计提供参考.     

DF7G模块化机车司机室的空调设计

通过计算分析以前DF7型机车司机室通风系统存在的缺欠,提出了DF7G型机车司机室空调系统新的设计理念。通过改进风道设计等,使DF7G型机车司机室空调系统通风得到改善,实际运用表明效果良好。     

Plant performance of a coal-fired MHD generator

The paper sets out, with reasons, the chosen values of the various parameters (air enrichment, air preheat temperature, magnetic field, duct length, duct velocity etc.) involved in the determination of the plant performance of a open-cycle steam-bottomed coal-fired MHD generator. The effect on the overall cycle performance of varying the important parameters in the system is considered. Optimum values of the chosen parameters have been obtained for maximum overall plant efficiency.     

某300MW发电机滑环烧损事故分析与处理

某电厂300MW机组发生发电机滑环碳刷烧损,针对发电机的实际烧损情况进行详细分析证明:集电环处风道堵塞、散热不好、弹簧特性改变、压力不均匀、电流分配不均、碳刷及弹簧片频繁跳动和报警信息没有及时发现等诸多因素,造成整个滑环及碳刷温度迅速升高,产生弧光,在滑环的高速旋转下形成环火,使碳刷、刷握、铜支架等烧软、烧熔,造成发电机滑环烧损事故,针对上述原因采取相应的措施,使发电机运行正常。     

退役航空涡扇发动机地面应用的有效途径之一_再热燃气_蒸汽联合循环

本文探讨以退役航空涡扇发动机作为燃气发生器,内函的燃气与外函的空气相掺混。经再热燃烧室加热后进入动力涡轮作功,并且应用余热锅炉回收－部分排气余热,产生蒸汽,驱动汽轮机作功所组成的再热热气－蒸汽联合循环。通过计算实例说明该循环具有输出功率大,循环效率具有相当大的提高等特点。     

空冷汽轮发电机转子风道中气体运动流场分析

针对转子高速转动的特点,分析了转子风道气体运动状态,建立了数值计算模型.分析结果表明,转子风道气体运动是由风扇和转子高速转动共同作用的结果,以吸入式空冷汽轮发电机通风结构为例,转子以3 000 r/min转速绕轴高速转动可以使风道中进风量由0.14 kg/s增加到0.21 kg/s,必须考虑转子转动对风道中气体运动的影响;粘性模型应选择无粘,相同条件下转子风道出口风速模型试验和数值模拟结果对比表明,数值模拟结果符合工程实际.转子风道中气体运动流场合理计算模型应为:以吸入式风扇和转子风道进口为进出口边界条件,流体边界条件考虑转子转动,墙边界条件中反映管壁表面粗糙度的相对粗糙度系数和常量分别取为k~+_s=500～1000和C_(ks)=1.0,粘性模型选择无粘,可用此计算模型对空冷汽轮发电机转子风道中气体运动流场进行分析.     

高温空气发生器实验台的研制

指出了发展生物质高温空气气化系统的必要性，介绍了其关键技术一高温空气发生器的工作原理；对高温空气发生器关键部件的结构设计进行了详细阐述，建立了高温空气发生器实验台，并在此装置上进行了冷态实验。实验结果表明：高温空气发生器可以正常稳定运行，整体性能满足设计要求，并且获得了重要的性能参数，为掌握高温空气性能并深入研究生物质高温空气气化系统作好了充分的实验准备。     

锅炉二次风道流动特性的模拟优化

以武汉武锅能源工程有限公司设计的二次风道为对象,运用数值模拟的方法考查了改造前后二次风道各出口空气的速度分布和质量流量分配情况。结果表明,通过布置弧形挡板,风道出口速度的均匀性显著提升,最大变异系数Cv由29%下降到9%,而且还避免了因风速不均引起的烧边现象。此外,改进后风道各出口空气的流量分配非常接近理想工况,与理想工况的偏差从9.9%缩小到2.1%。     

Innovatory designs for ducted wind turbines

Designs for conventional ducted wind turbines usually include a large inlet for more absorption of the airflow. However, the most efficient solution should be increasing the speed of wind. In this paper, a bucket-shape ducted wind turbine is proposed and studies show that a sucking effect can be produced according to the Bernoulli's principle, and this significantly increases the wind speed inside the duct and substantially enhances the efficiency of the wind turbine. Moreover, the geometry of the duct is optimized by the combination of an improved complex algorithm, an object-oriented optimizing program interface, and simulations by CFD software. According to the analyses, the optimal shape for the interior of the duct appears to be an unconventional nozzle, which extends the range of wind speed by 60%.Based on this bucket duct equipped with the optimal nozzle, we have practically designed and constructed a wind power generator. The results of the field tests show that the proposed ducted turbine does improve the flow around the generator and thus increase its power extraction efficiency by about 80%.     

Thermal modeling of integrated roof air heater for passive solar space heating of a non-air-conditioned building

This communication presents the periodic heat transfer analysis for solar space heating of an unconditioned building with an integrated roof air heater. The system consists of an air duct within the roof such that the air is continuously or intermittently forced to circulate the cooler room air through the inlet of the air duct. Time dependence of the air flow is represented by a step function of time for daily operation and, hence, has been expressed as a Fourier series in time. The analysis takes into account air ventilation, ground heat conduction and furnishings. The effects of depth of the air duct from the outer surface of the roof and the magnitude and duration of air flow rate on indoor air temperature have been studied for a typical cold winter day in Delhi. It is seen that a time dependent air flow through the duct is desirable from the point of view of increasing the indoor air temperature in the case of a bare roof. However, in the case of a blackened and glazed roof, continuous air flow is needed for increasing the room air temperature. The results are desirable from the point of view of efficient space heating of solar passive buildings.     

Improvement in solar air collector performance with vaned diffuser

Modifications made in a solar air collector inlet duct to achieve uniform velocity of air in the absorber duct are described. Measurements of temperature and pressure at various points in the duct gave information on the distribution of air in the absorber duct. A thermal performance test conducted on the collector with a vaned diffuser showed some significant improvement compared with a diffuser without vanes.     

Ventilated facades energy performance in summer cooling of buildings

The use of ventilated facades and roofs can help to reduce summer thermal loads and, therefore, the energy consumption due to air-conditioning systems. This paper discusses a simple analytical method for the calculation of the energy saving achievable by using ventilated facades in which the air flow inside the air duct is due to stack effect. Two particular cases of outstanding importance are investigated. The first in which the inner masonry wall is given, and the air duct and the outer facing have to be optimized. The second in which the outer facing is given, and the inner masonry wall and the air duct have to be optimized. The first case can occur in existing buildings renovation, while the second case can occur during the design process. Finally, the influence of the variation of some quantities necessary for calculation on the energy performance of ventilated facades is investigated. In particular, the energy performance of such facades results to be strongly influenced by the air duct width, the insulating material distribution, the solar radiation intensity, the wall outer surface thermal resistance and the roughness of the slabs delimiting the air duct.