汽轮机低压转子末级叶片裂纹及叶根销钉断裂失效分析

本文对汽轮机低压转子末级叶片的裂纹和叶根销钉断裂失效问题进行了详细分析。通过对损坏叶片和销钉的外观观察、微观结构分析、材料成分检测以及运行环境的综合评估,揭示了失效的主要原因。研究发现,叶片裂纹主要是由于长期受高温、湿度变化和蒸汽侵蚀导致的材料疲劳累积,以及叶片设计中的应力集中现象所致;叶根销钉的断裂失效主要与运行过程中周期性的抗拉应力过大以及振动疲劳有关。研究结果表明,对汽轮机低压转子末级叶片裂纹和叶根销钉断裂失效机理的分析能够为汽轮机低压转子末级叶片和叶根销钉的设计、材料选择、加工制造和运行维护提供科学依据。     

大功率空冷机组末三级动叶片的设计及其频率试验

介绍了大功率空冷机组末三级动叶片的设计及其动静频试验情况。通过计算和试验的对比分析,改进了次次末级动叶片的初始设计状态并确定了末三级动叶片围带的最终尺寸。试验表明,大功率空冷机组低压末三级动叶的设计是成功的,叶片能满足空冷机组的长期安全运行要求。     

700毫米长叶片枞树型叶根各齿受力分布的计算分析

一、引言枞树型叶根能利用各对齿逐对承担叶片离心力载荷,同时逐步缩小齿根截面,从而充分利用材料强度,减小了叶根及轮缘的尺寸,因此这种叶根型式主要用在叶片离心力载荷较大或大功率机组的调节级及末几级长叶片中。     

905毫米长叶片叶根拉断试验

1 概述在汽轮发电机组运行中,因汽轮机叶片枞树型叶根受力不理想而导致叶片或叶根断裂的事故已屡见不鲜。这是因为,迄今为止,对叶根受力尚不能完全依靠计算方法获得准确的数据,因而往往要借助实验手段才能反映叶根真实的受力状况。为确保机组的安全运行,避免叶片(叶根)的断裂事故,用有效的实验方法获得叶片(叶根)的真实受力状况是很有必要的。国外一些工业发达国家,在开发设计一种新型叶根后均进行实物叶根的拉断破坏试验,其目的就是为了考核叶根的强度储备是否满足要求。国内以前由于受到拉力试验机     

引进300MW汽轮机次末级叶根的强度计算

引进３００ＭＷ汽轮机次末级叶根的强度计算刘岩，余耀，诸玉喜１前言外高桥电厂１号机为我厂生产的引进型３００ＭＷ机组，该机在运行１６４６小时后，次未级叶片（４７４ｍｍ叶片）叶根第１对肯发生断裂。为此，有必要对该叶根进行三维应力场分析，找出其应力集中的区域...     

用三维有限元确定枞树型叶根的结构

枞树形叶根在强度性能上的主要优点是它能利用各对齿逐对承担叶片离心力荷载,同时逐步缩小齿根截面,从而充分利用材料强度,减小叶根及轮缘尺寸。所以在汽轮机设计中,对末级叶片离心力荷载较大的情况下,大多采用枞树形叶根。从以往一些电厂叶片     

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。     

超临界600MW机组用给水泵的汽轮机末级叶片的开发

针对给水泵汽轮机的运行特点,设计开发新的末级叶片,以便满足给水泵汽轮机运行时气动、强度、振动要求。     

五叉等强叶根型线设计

一、前言长叶片是汽轮机的关键部件之一,对于长叶片,不仅要求其气动性能、强度振动特性优良,而且要求叶根必须安全可靠。为此,长叶片叶根的设计是一项很重要的工作。目前,随着国内外大功率汽轮机的发展,末级叶片的长度也在不断增加,使得叶根承受的离心力显著增大。解决这一问题的途径是:采用枞树形叶根,增加叉型叶根的叉腿及轮缘宽度,增加叉型叶根的叉腿数量,采用等强叉型叶根或者采用外包式叉型叶根     

330 MW空冷汽轮机低压末级712 mm动叶片的设计

为了确保新设计的330 MW空冷汽轮机低压末级712 mm动叶片能够高效、安全和稳定的运行,分别从结构、气动、强度和振动方面对叶片进行优化设计。7年多机组实际的运行考验证明712 mm动叶片达到了预期设计优化的效果。     

枞树型叶根间隙流量试验与数值研究

为了研究气流在涡轮枞树型叶根间隙内的流动特性,以及校核与优化现有叶根间隙流量计算关联式。以某型地面燃气轮机涡轮一级转子枞树型叶根间隙为对象,对其进行了流量试验与三维数值模拟研究。测量了进出口压比范围为1～2工况下通过叶根间隙的流量值,该流量值对应的流动雷诺数范围为1 700～16 500。并在ANSYS/CFX中对相同模型及进出口边界条件下叶根间隙内的流动进行数值模拟,获得叶根间隙截面流动结构,同时计算了长径比39～118范围内,不同压比工况下通过叶根间隙的流量。研究表明：随着压比增大,流过叶根间隙的流量增大趋势逐渐减小;随着长径比增大,流过叶根间隙流量逐渐减小;文献[10-11]提供的叶根间隙流量计算关联式的计算结果与试验测量值平均误差16.3%;与关联式流量计算值随压比变化趋势不同,试验测量值分布曲线随压比增大无明显转折;两端宽、中间窄的叶根间隙通道结构使得流道内层流与湍流共存,从而造成了上述偏差;针对上述偏差,根据试验与三维数值模拟结果拟合了新的叶根间隙流量计算关联式。     

Influence of blade rotation on the lightning stroke characteristic of a wind turbine

The blades of a wind turbine rotate during normal operation. To investigate the influence of blade rotation on the lightning‐attracting ability of a wind turbine, a discharge test platform is designed for scaled wind turbines. The 50% impulse voltages and flash probabilities of the scaled wind turbines with gap distances of 1 to 8 m in the static and rotary conditions are determined by using the discharge test and selective discharge test. The discharge test for a single wind turbine with a gap of 1 to 2 m indicates that the breakdown voltages of the gap between the scaled turbine and electrodes increases with an increase in the blade rotation speed. However, the discharge test with a gap distance of 4 to 8 m indicates that the breakdown voltage of the fan decreases with an increase in the blade rotation speed. The test results of the scaled dual wind turbines experiment have the same rules. To explain this phenomenon, the influence of wind speed on the space‐charge distribution and electrical field intensity of corona discharge is simulated in the background of a target thundercloud. The rotation of the fan reduces the space‐charge density near the area of the blade tip, which leads to an increase in the field strength near the blade tip of the wind turbine and a decrease in the field strength away from the blade tip. This influence varies in short and long air gap, resulting in opposite relationships between discharge voltage and distance from the tip of the turbine. The results can provide a reference for the lightning protection of wind turbines.     

超超临界1000MW汽轮机动叶片静频试验研究

汽轮机动叶片振动问题是叶片运行过程中的主要问题之一。为使机组安全运行,通常需要测定和调整叶片的静频。该丈针对1000MW超超临界汽轮机指定级叶片的静频试验内容与方法进行介绍,并对试验数据进行总结分析,给出了各级叶片静频数据及振型特性,并与理论计算值进行比对分析,为理论计算修正提供参考。     

Full‐scale test of trailing edge flaps on a Vestas V27 wind turbine: active load reduction and system identification

A full‐scale test was performed on a Vestas V27 wind turbine equipped with one active 70 cm long trailing edge flap on one of its 13 m long blades. Active load reduction could be observed in spite of the limited spanwise coverage of the single active trailing edge flap. A frequency‐weighted model predictive control was tested successfully on this demonstrator turbine. An average flapwise blade root load reduction of 14% was achieved during a 38 minute test, and a reduction of 20% of the amplitude of the 1P loads was measured. A system identification test was also performed, and an identified linear model, from trailing edge flap angle to flapwise blade root moment, was derived and compared with the linear analytical model used in the model predictive control design model. Flex5 simulations run with the same model predictive control showed a good correlation between the simulations and the measurements in terms of flapwise blade root moment spectral densities, in spite of significant differences between the identified linear model and the model predictive control design model. Copyright © 2013 John Wiley & Sons, Ltd.     

Optimization of Root Section for Ultra-long Steam Turbine Rotor Blade

This study presents the comparison of aerodynamic performances of two successive designs of the root profiles for the ultra-long rotor blade equipped with a straight fir-tree dovetail. Since aerodynamic and strength requirements laid upon the root section design are contradictory, it is necessary to aerodynamically optimize the design within the limits given by the foremost strength requirements. The most limiting criterion of the static strength is the size of the blade cross-section, which is determined by the number of blades in a rotor and also by the shape and size of a blade dovetail. The aerodynamic design requires mainly the zero incidence angle at the inlet of a profile and in the ideal case ensures that the load does not exceed a limit load condition. Moreover, the typical root profile cascades are transonic with supersonic exit Mach number, therefore, the shape of a suction side and a trailing edge has to respect transonic expansion of a working gas. In this paper, the two variants of root section profile cascades are compared and the aerodynamic qualities of both variants are verified using CFD simulation and two mutually independent experimental methods of measurements (optical and pneumatic).     

CGT25D国产管道燃气轮机事故分析及隐患处理

中国石油西气东输联合中船重工第703研究所和哈尔滨汽轮机有限公司三家联合试制了3台CGT25D天然气管道用燃气轮机。由于在加工制造和装配过程的细节把关不严谨,首台国产试制的CGT25D管道燃气轮机仅仅运行了3 577 h就出现了低压压气机一级动叶片叶根断裂事件,造成了整个燃气轮机压气机报废。第二台CGT25D燃气轮机在工厂试验期间又出现振动问题。中船重工第703研究所结合首台机组的故障原因分析情况,对第二台CGT25D燃气轮机进行故障和隐患排查并进行了及时修复和补救处理,机组已在西气东输管道公司衢州压气站投产并正常运行。第三台国产CGT25D燃气轮机吸取了教训并已在西气东输广南线梧州压气站投产运行。本文简述了首台机组故障分析和第二台机组的故障隐患排查情况,并对处理过程进行了反思并强调注重细节是燃气轮机国产化战略成功的关键。     

有限元技术在空冷汽轮机长叶片设计中的应用

首先采用有限元技术对某空冷汽轮机低压末级长叶片的整圈振动特性进行计算,随后时由整圈自锁长叶片围带和凸台不同接触间隙造成整圈振动特性的变化进行了数值分析,最后对空冷低压长叶片各个部分的强度进行了分析.有限元计算结果与动频试验的结果偏差很小,强度计算结果也满足设计规范的要求.这些先进计算技术的应用,大大缩短了长叶片的研发周期,保证了空冷低压长叶片的安全运行.     

弯扭耦合作用下变频风机叶片断裂分析与治理技术研究

针对某变频运行风机发生的叶片断裂故障,采用无线应变测试技术获取了不同工况下转轴扭矩脉动特性。建立叶轮叶片有限元模型,获取风机各阶模态特性;将实测脉动扭矩作为激励,计算扭矩脉动下叶片所承受的应力特性。结果表明：电机输出谐波可能激发叶片轮盘弯扭耦合共振,导致叶片局部应力增大,进而疲劳断裂;叶片顶部加之字形加强筋可以有效减小叶片振动,预防断裂。     

增压器压气机叶片结构/振动一体化优化设计

以废气涡轮增压器压气机叶轮为研究对象,创建了压气机叶片的三维参数化模型,通过全三维流场仿真分析,得到压气机的气动性能及叶片表面的压力分布.在不改变叶片形状、保证压气机气动性能的情况下,对叶片的静强度及振动特性进行了一体化优化设计.以叶片4个关键截面的叶顶、叶根厚度为设计变量,以离心力及气动压力作用下叶片的最大Mises应力、叶片的一阶动频为约束,以叶片体积为目标函数,在iSIGHT优化平台上集成了I-DEAS、ANSYS软件,采用混合整型优化和自适应模拟退火算法的组合优化方法,在满足叶片静强度小于屈服强度和一阶动频大于3倍工作频率的条件下,叶片体积(质量)减小了14.7%.