弹性齿汽封叶顶碰摩对汽轮机运行稳定性的分析

为减少漏汽损失,提高大参数汽轮机组的效率,设计一种小间隙汽封将十分必要.对一种新型叶顶弹性齿汽封的动静碰摩进行力学建模并进行了动力学分析,分析的结果表明,叶顶弹性齿汽封的小间隙安装,对汽轮机机组的运行稳定性不会造成影响,也表明这种设计的可行性.     

高低齿汽封与蜂窝汽封及孑L式阻尼汽封密封性能的比较

使用商用CFD软件Fluent对高低齿汽封、蜂窝汽封及孔式阻尼汽封进行了三维数值模拟,得到三种汽封在不同压比、轴转速和汽封相对间隙时的密封性能,并将高低齿汽封和蜂窝汽封计算值与试验数据进行了对比．结果表明：高低齿汽封流量系数随压比增大而增大,随转速加快而略有减小,随相对间隙的增大而减小;蜂窝汽封与孔式阻尼汽封的流量系数均随压比增大而减小,随转速加快而略有减小,基本呈直线变化规律,随相对间隙的增大而增大;在相同的条件下,蜂窝汽封的漏汽量比高低齿汽封的漏气量减少10％,而孔式阻尼汽封的漏汽量比蜂窝汽封漏汽量减少6％．     

汽轮机叶顶汽封间隙内的流动损失分析

为了揭示叶顶汽封结构变化对泄漏损失的影响,提高汽轮机运行效率,数值研究了平齿汽封、高低齿汽封和侧齿汽封3种不同叶顶汽封结构下汽轮机高压转子间隙泄漏的流动形态、间隙涡系的形成机理和发展规律,研究表明:在叶顶汽封腔室复杂的周向螺旋状的涡动中,泄漏流体的周向速度是影响漩涡耗散的一个重要因素;高低齿及侧齿的汽封结构可以增强漩涡之间的相互作用,降低泄漏流体的周向速度,使漩涡在腔室内的耗散更加充分;由于掺混损失降低,高低齿及侧齿汽封的泄漏总损失较平齿汽封相比分别下降7.1%和9.8%。     

枞树型叶根间隙漏气对级性能影响的试验研究

隔板汽封间隙、叶根径向汽封间隙及枞树型叶根与轮槽间隙三者之间匹配设计对透平级效率及转子推力的大小有显著影响。文章针对某1000 MW高压末三级空气透平试验进行相关研究,保持隔板汽封间隙、动叶根部径向汽封间隙不变的条件下,对枞树型叶根间隙改变前后级性能的变化进行试验分析。试验结果表明,叶根间隙封堵后,透平级效率降低,根部反动度升高,转子推力变大。合理的枞树型叶根间隙的存在有利于提高级性能,汽轮机通流设计时应注意叶根间隙与隔板汽封间隙的优化匹配。     

汽轮机直齿与斜齿汽封内部流场的数值计算与结构优化

利用数值计算软件对汽轮机光轴直齿与斜齿两种结构的迷宫式汽封内部流场进行了数值研究,给出了汽封内部流动特性和漏汽量随相对齿间距和齿倾斜角度变化的规律.在汽封段轴向长度一定和相同的流动条件下,存在最佳齿数范围和倾角范围,它可使迷宫式汽封的漏汽量最小.     

国产50MW汽轮机轴端汽封的改造

针对两台国产50MW汽轮机轴端阔气汽封严重漏汽、冷凝器真空偏低问题。根据计算汽封漏汽量公式,结合该机轴端汽封系统的运行状况和原汽封的结构参数（齿型、齿数）及安装间隙,分析了诸多影响汽封漏汽量的因素,找到了存在问题的根本原因。改造了原轴端汽封的结构、材料及其安装间隙要求。经实践运行验证,存在问题得到解决,节能降耗明显。     

提高汽轮机通流部分汽封汽密性研究

阐述了汽封、汽封有效齿等基本概念。依据相关理论,概述了影响汽封密封效果的因素。扼要从设计、安装与运行维护、汽封齿安装与调整方面分析存在的问题。应用基本理论,结合汽轮机汽封设计和转子密封处的结构特点,针对存在的问题,就如何设计、加工汽封齿,以及安装与调整提出技术改进建议,提高汽封气密性效果。     

汽封流场及泄漏特性的数值模拟分析

应用FLUENT软件对汽轮机的汽封系统进行了数值模拟:分别建立了数学模型和划分了计算网格,同时设置了边界条件和选取了标准双方程模型,并对汽封结构的影响因素:齿数、密封间隙、齿厚度、齿高进行了分析.     

自调间隙汽封—节能又安全

美国通用电气公司曾介绍“可变间隙汽封”，我国又将传统汽封改造为自动调整间隙汽封，现简要介绍国产汽轮机改进汽封的结构及其工作原理，并提出个人建议。     

机夹可转位汽封齿车刀设计

文章对汽封齿车刀材料选择进行了介绍，着重介绍了汽封齿夹齿刀具设计理念，夹紧结构选择，几何参数选择，对设计思路进行了较详细的叙述，并对其使用效果进行了分析。     

汽封用蛇形弹簧的试验及分析

目前现场使用一种一端带弯头的蛇形弹簧,在运行时,由于同一根弹簧上各波的弹力相差很大,导致与之相配用汽封段的汽封齿被严重磨损,使机组效率降低.实验研究表明,当弹簧采用中间定位时,在弹簧受力变化时,整根弹簧从头到尾的波高变化量基本一致.     

超微燃气透平非接触式密封的三维CFD数值分析

提出将螺旋密封应用于超微燃气透平气体介质密封.采用三维CFD数值计算方法分析了微尺度下无密封齿、迷宫密封和螺旋密封的泄漏规律及流场规律.结果表明:微尺度下迷宫密封最优齿数的存在与进、出口压比和密封间隙有关,而齿形对密封性能的影响没有宏观尺度下明显.在小压比下,密封轴转速对螺旋密封性能的提高明显,其泄漏减少量最高可达19.3%,因此螺旋密封显然优于迷宫密封和无密封齿;在大压比下,螺旋密封与迷宫密封的效果相当,均优于无密封齿.当压比为2时,迷宫密封的泄漏率比无密封齿降低27.1%.     

MS9001E燃气轮机透平密封改造

浙江镇海的300MW燃气—蒸汽联合联合循环电站由两台100MW的MS9001E燃气轮发电机组、一台100MW蒸汽轮发电机组及两台无补燃余热锅炉组成。燃气轮机由美国GE公司提供,机组起停机时用0#柴油,正常运行时燃用180cSt重油。其中#8燃气轮机(到性能改造前总运行时间37 290·5小时、启动8     

Modeling of cracking of the glass-based seals for solid oxide fuel cell

For planar SOFCs the seal is a critical component, potential fracture in the seal needs to be investigated in order to enhance the reliability of the seal. A model based on the classical beam bending theory and the fracture theory of ceramic materials has been developed for predicting the crack extension in the seal. The model reveals that the resistance of the seal to cracking on cooling is mainly affected by two factors: the seal thickness and the CTE mismatch. Furthermore, a cracking diagram is established to reveal the effects of the seal thickness and CTE mismatch on the crack extension behavior. It shows that the ‘no cracking’ area increases with decreasing seal thickness, and larger CTE mismatch requires a thinner seal to avoid cracking. The model and the cracking diagram are experimentally validated through monitoring the leakage rate of a glass-sealed chamber, and the crack extension deduced from the measured leakage rate shows good agreement with those predicted by the model. The proposed model can serve as a useful tool in sealing design of SOFC.     

Dimensional analysis on resistance characteristics of labyrinth seals

Experimental investigation of stepped and straight-through labyrinth seals was designed to study the sealing performance of two different typical labyrinth seals.In order to facilitate dimensional analysis on the flow resistance characteristics of labyrinth seals,the variable cross-section of the flow channels are considered as constant cross-section flow.The mechanical energy loss of flow caused by throttle turbulence intensity is considered as caused by friction along the way.The friction coefficient of stepped labyrinth seals is bigger than that of straight-through labyrinth seals by more than 40% for the same Reynolds number and the ratio of equivalent diameter and the seal length.The expression of friction coefficient /and /Re are obtained from experimental data.The verifications indicate that the expressions are highly accurate.The contribution to the total pressure drop of each tooth cavity gradually becomes less along the flow direction.     

氦气透平压气机组合弹性环密封试验研究

氦气透平压气机采用间冷回热方式的闭式循环,因此高低压压气机以及涡轮进排气口处的密封与外层压力壳间就形成了不同压力的腔室,针对其各不同温度和压力的腔室采用组合弹性环密封.为验证组合弹性环的密封效果,设计了密封试验器和与机组上的组合弹性环完全一致的密封试验件,并在密封试验台上分别采用氦气工质和空气工质进行了试验对比.试验结果表明,组合弹性环具有良好的密封效果,在低压压气机出口进口、高压压气机出口进口以及高压压气机出口涡轮出口3处密封的泄漏分别占设计流量的0.0322‰、0.1035‰、0.1282‰,与空气介质相比,当封前压力为0.6～1.0 MPa时,氦气的泄漏约为空气泄漏的2倍,当封前压力较低时(0.1～0.2 MPa),氦气与空气的泄漏比较接近.     

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Visualization and flow measurements were performed for the flow field radially beyond the rims of isolated flat circular disks rotating in their own planes. The investigation included effects of disk thickness and speed of rotation. Flow in the near-rim region has similarities to that of the near-wake region of bluff-tailed bodies, with vortices being found there. In the same region there is a large negative radial gradient of whirl velocity. Further from the disk rim the flow becomes a jet with straight mean streamlines. The relative degree of swirl in the far-jet varies with disk thickness and speed.