蜂窝汽封在中小型汽轮机组的应用

本文介绍了蜂窝汽封的结构及工作原理,分析了该汽封与传统梳齿密封相比的优势,重点阐述了该汽封技术在中小型汽轮机组的应用,根据应用的实际效果,可以得出该汽封技术在降低汽轮机蒸汽泄漏量、提高汽轮机效率上效果显著。     

蜂窝密封的封严特性研究

对于蜂窝深度为3.0mm、蜂窝芯格尺寸(蜂窝六边形的对边距离)分别为3.2mm、1.6mm和0.8mm三种蜂窝密封,研究了在不同转速、压比下的封严特性。试验结果表明,三种蜂窝密封之中,芯格尺寸为1.6mm的蜂窝密封封严效果最好,说明蜂窝密封芯格尺寸的大小对其漏气量的影响并不呈线性规律。计算结果表明,蜂窝宽度与蜂窝深度比值适当时,能量耗散效果好,密封的漏气量较小。蜂窝宽度与蜂窝深度的比值偏大或偏小时,能量耗散效果差,密封的漏气量都较大。     

蜂窝密封的设计、仿真及其应用研究

针对某大型煤化工企业所用汽轮机出现的高温蒸汽泄漏问题,对汽轮机前汽封加以改造,进行了基于蜂窝密封技术的结构设计、仿真分析和应用研究.在原始梳齿密封结构的基础上,进行了蜂窝密封结构设计;利用CFD软件对密封流场进行了仿真分析,研究了梳齿密封和蜂窝密封的密封性能差异;研究了梳齿结构、蜂窝芯格深度和蜂窝芯格直径对蜂窝密封性能...     

新型汽机蜂窝密封的应用

韶钢能环部发电工段4#汽轮机存在前、后汽封漏汽大的问题,影响真空和效率。通过应用新型蜂窝密封进行改造,解决了问题,使设备平稳运行。     

汽轮机侧齿汽封与梳齿汽封流动特性研究

对汽轮机上侧齿汽封和梳齿汽封进行建模,基于数值求解方法,用有限体积法对控制方程进行离散,并求解湍流模型的封闭方程组,在不同的进口压力下,分析了侧齿汽封和梳齿汽封的三维流动特性。分析结果表明侧齿汽封并不一定优于梳齿汽封,对于高低齿形式的汽封,梳齿汽封的密封性能较好,泄漏量较少,对于平齿形式的汽封,侧齿汽封的密封性能较好,泄漏量较少,转子的凸台对汽封泄漏量的影响很大。为汽封齿的设计加工提供了理论依据,为汽轮机的汽封改造提供了技术参考。     

汽封管路数值模拟计算及改进研究

针对汽封的密封性问题,对汽封管道抽吸压力传播对汽封漏气量的影响、复杂通流结构对传递到汽封侧抽吸压力及汽封漏气量的影响、汽封流量理论计算与CFX模拟计算结果之间存在的误差等方面进行了研究。对汽封进行了三维实体建模及数值模拟,对汽封管道性能参数计算结果、汽封管道截面压力分布情况和截面速度分布情况进行了分析,提出了一种在现场改造中简单有效而又经济的改进型汽封管路结构。研究结果表明:通过加粗中间段平衡管道,该改进型结构可有效减少汽封管道压损,增大过渡段压力,减少高压段漏气,提升汽封效果,提高汽轮机运行效率和可靠性。     

汽轮机刷式汽封设计

介绍了刷式汽封的研究与应用发展状况,阐述了刷式汽封的基本结构,分析了刷式汽封与传统梳齿密封不同的密封机制和密封效果.根据某国产汽轮机高压缸前端轴封参数对刷式汽封泄漏量进行计算,并对结构参数、材料进行选择.     

AP1000核电汽轮机轴封系统介绍

轴封系统通过汽封、阀门、轴封冷却器、排气风机等设备及附属仪控制表实现实现对汽轮机端部的密封,同时回收阀杆漏气和汽、气混合的蒸汽和能量损失.     

接触式蜂窝汽封在12MW汽轮机中的应用

广州珠江啤酒股份有限公司热电厂3#汽轮机组在运行过程中,汽封漏汽量大,效率和真空严密性下降;同时高压汽封漏汽造成润滑乳化严重,影响机组安全运行。采用接触式蜂窝汽封对汽封系统进行改造,有效解决了问题。     

背压式汽轮机轴端汽封泄漏分析及改造

汽轮机是用蒸汽来做功的旋转式热能动力机械,具有效率高、功率大、转速容易控制、寿命长、运转安全可靠等优点,但轴端汽封易泄漏也是汽轮机常见故障,本文通过对NG25-20背压式汽轮机轴端汽封泄漏原因分析及蜂窝密封改造处理,消除了泄漏,提高了机组运行的经济性和安全性。     

Effect of honeycomb seals on loss characteristics in shroud cavities of an axial turbine

The loss in efficiency due to shroud leakage or tip clearance flow accounts for a substantial part of the overall losses in turbomachinery.It is important to identify the leakage loss characteristics in order to optimize turbomachinery.At present,little information is available in the open literature concerning the effect of honeycomb seals on the loss characteristics in shroud cavities of an axial turbine,despite of the widespread use of the honeycomb seals.Therefore,interaction between rotor labyrinth seal leakage flow with and without honeycomb facings and main flow is investigated to provide the loss characteristics of the mixing process of the re-entering leakage flow into the main flow.The effects of honeycomb seals on the flow in shroud cavities and interaction with the main flow are analyzed.An additional study on the impact of subtle shroud cavity exit geometry is also presented.The investigation results indicate that the honeycomb seal affects the over tip leakage flow and reduces mixing losses when compared to the solid labyrinth seal.The leakage flow interactions with the main flow have considerably changed the flow fields in the endwall regions.The proposed research reveals the effects of honeycomb seals on the loss characteristics in shroud cavities and the impact of subtle shroud cavity exit geometry,and it is helpful for the design optimization of turbomachinery.     

台阶齿蜂窝衬套封严结构风阻特性的研究

对台阶齿-蜂窝衬套篦齿封严结构的泄漏特性和风阻特性进行数值模拟,得到流体的泄漏特性和风阻特性随转速、压比、节流间隙和蜂窝结构参数的变化规律.结果表明:泄漏流体风阻生热总温升随转速和蜂窝单元直径的增大而增大,随压比和节流间隙的增大而减小;蜂窝深度对风阻生热影响不大,基本可以忽略.     

气液两相条件下迷宫密封泄漏分析与试验研究

为解决大型船用柴油机曲轴箱轴端漏油问题,通过仿真和试验对气液两相条件下迷宫密封的泄漏行为开展研究。基于FLUENT软件进行迷宫密封流场仿真,利用离散相模型开展油滴逃逸行为分析,揭示迷宫密封在气液两相环境中的密封机理和泄漏规律。在试验器上模拟了曲轴箱密封的实际结构和工况条件,测量了不同转速条件下的漏油速率,研究了密封装置中的不同结构特征的功能作用,最终提出了两种改进措施并验证了措施的有效性。研究结果表明：交错迷宫结构与直通型迷宫结构相比可以更显著地减少空气泄漏,增加交错迷宫结构可大幅减少空气对液相介质的向外输运,此外,合理利用迷宫结构进行回油亦能显著减少滑油泄漏。     

蜂窝结构对篦齿-蜂窝密封封严性能的影响

为提高压气机级间气路封严密封性能,在传统六边形蜂窝的基础上,改变其结构得到方形蜂窝和圆形蜂窝,数值研究不同间隙、压比和转速下蜂窝结构对篦齿-蜂窝密封封严性能的影响。结果表明:间隙增加时,篦齿密封、六边形蜂窝密封、方形蜂窝密封、圆形蜂窝密封4种密封方式泄漏量均线性增加,但由于蜂窝破坏了流场透气效应,故篦齿-蜂窝密封泄漏量增速最慢,其中圆形蜂窝密封封严效果最好;压比增加时,4种密封方式泄漏量均增加,但篦齿及蜂窝腔室内形成漩涡亦随压比增加而愈发强烈,耗散更多能量,故泄漏量增速逐渐变缓;转子转速增加时,流体环向速度增加,4种密封方式泄漏量均减小,而蜂窝环向切割流体形成漩涡耗散能量,故篦齿-蜂窝密封减小幅度较大。在大间隙高压比高转速的工况下,篦齿-蜂窝衬套结构封严效果更好,其中篦齿-圆形蜂窝密封最具优势。     

蜂窝密封流场和泄漏特性的实验研究

利用烟线法,显示了蜂窝腔中空气的流动情况,揭示了蜂窝腔中旋涡的结构特点。表明在相同的入口条件下,间隙越小,进入蜂窝腔的气流与水平面的夹角越大,且旋涡体积越大、中心位置越靠近底面。同时,在不改变实验其它参数的情况下,改变蜂窝的深度,通过实验观察蜂窝密封的泄漏量。结果表明,在不同的入口压力情况下,蜂窝深度与蜂窝对边距的比值为0.52左右时,蜂窝密封的泄漏流量最小。     

大型水泵导轴承梳齿迷宫密封研究

推导了大型水泵油润滑导轴承梳齿迷宫密封泄漏量计算公式。通过实例计算了梳齿迷宫密封的泄漏量及各密封段的压降,分析了各段对密封效果的影响。比较了梳齿迷宫密封与端面密封的密封效果,分析了油润滑导轴承浸水的可能原因,指出了梳齿迷宫密封的适用性。结果表明:在水泵导轴承梳齿迷宫密封中O形密封圈的磨损量对泄漏量影响很大,O形密封圈必须选用耐磨性能好的材料,并控制泵轴摆度以减小O形密封圈的磨损量;在正常运行情况下梳齿迷宫密封的泄漏量远大于端面密封,因此要保证足够的排漏水能力,以免因排漏水不畅造成导轴承浸水。     

Leakage from labyrinth seals under stationary and rotating conditions

Although the leakage flow through labyrinth seals under stationary conditions has been examined by many investigators a reliable prediction of the effect of various labyrinth parameters on leakage rate has not been reported so far. The theoretical models for the seals proposed in most of the previous literature provided results with considerable differences and contradictions in some cases. The structure of the laminar incompressible flow and the performance of a number of seals of various shapes for both stationary and rotating conditions are investigated in this paper. The theoretical treatment is based on the formulation of three-dimensional axisymmetric momentum and continuity equations for labyrinth shapes having small height to radius ratio as is always the case in turbomachinery, rotodynamic pumps and many hydraulic devices. It is found in this paper that shaft rotation is only beneficial for the up-the-step seal, has no effect on grooved shaft and grooved casing seals and has an adverse effect on the down-the-step seal. It is also found that the use of a smaller clearance size at the entrance makes some improvement in the performance of the grooved shaft and down-the-step seals depending on the value of the height to width ratio of the seal.     

汽轮机进汽管道压力脉动及其对轴系扭振稳定性的影响

介绍了一种能导致汽轮机轴系扭振失稳的因素。在一次电厂试验中发现,调节汽阀的快速操作会激起进汽管中的压力脉动;对配有高速调节系统的汽轮机,如果蒸汽管道压力脉动的固有频率与轴系扭振固有频率相近,则会发生轴系不稳定扭振,并可能造成轴系破坏。     

A Study of Characteristics of the Controlled Oil Leakage of Valve-Stem Seals for Automotive Engines

It is well known that the valve-stem seal has been used for the valve-stem application of automotive engines, and influences the lubricating status between the valve stem and a valve guide. The valve-stem seals are important in controlling consumption of lubricating oil for engines and in preventing air pollution.

It is necessary that valve-stem seals have stable controlled oil leakage characteristics, Q (cm³/s), relative to variables such as oil viscosity, shaft speed and shaft-surface roughness. In this paper, characteristics of the controlled oil leakage on valve-stem seals have been discussed by applying an inverse problem of hydrodynamic lubrication.