离心压缩机转子与密封碰磨的故障诊断及特征分析

某离心压缩机在稳定的低转速机械运转阶段,低压缸各振动测点均出现振动爬升的现象,最终导致振动联锁停机。为查清机组振动超标原因,对机组机械运转全过程的轴振动进行了测试与分析。根据低压缸振动的历史趋势并结合振动频和时域特征分析,判断该机组振动超标的原因是由转子与定子碰磨造成。为进一步查找振动原因,对低压缸进行解体检查,发现密封齿磨损严重并有少量密封碎屑。调整密封间隙后重新进行机械运转,机组运转情况良好,说明低压缸振动超标的原因查找正确。     

原料气压缩机低压缸排气端轴承振动的分析

通过对原料气压缩机高压缸入口介质温度降低，破坏高、低压缸原始对中情况的分析，认为排气端轴承产生异常振动的原因是由于轴颈与径向轴承发生碰后造成的，并通过轴心轨迹和频谱分析对这一现象进行了说明。     

发动机低涡轴碰磨故障的装配工艺分析

针对航空发动机低压涡轮轴的碰磨故障,从装配工艺性出发,进行结构特点和工艺方法分析,通过定心引导分析、吊装稳定性分析、碰磨风险计算,得出装配过程中低压涡轮轴的碰磨原因。提出增加后支点定心引导、提高定心配合精度等改进措施,实现低压涡轮轴的双支点水平定心引导装配,解决低压涡轮轴表面防腐漆的碰磨脱落问题。     

600 MW空冷机组给水泵振动异常原因分析及处理

针对600 MW空冷机组给水泵振动大的问题,分析了振动产生的原因为质量不平衡和动静碰磨。水泵转子经过动平衡后,不平衡分量很小,动静碰磨更加严重,说明动平衡虽减小了不平衡力,却增加了法向碰磨力,碰磨引起的振动更大。根据试验结果,采取减小4号轴瓦顶隙和给水泵转子精密动平衡的方法,振动问题得到解决。     

切除低压缸运行风险及策略分析

对于汽轮机切除低压缸运行来说，在实际运行状况中存在四种风险，分别是叶片颤振、动静碰磨、叶片鼓风发热以及叶片水蚀，所以众多管理低压缸运行风险的相关研究，都是围绕着此四种风险进行详细的分析和讨论。随着国家电力资源的越来越丰富，我国电力产能在某一时刻会出现产能过剩的情况，进而就会导致火电机组的调峰需要逐渐增加，西方发达国家的火电机组调峰经验要领先于我国，从而我国通过借鉴先进的火电机组调峰经验，不断提高我国自身火电机组调峰经验。目前，我国部分电厂已经对低压缸进行开展创新活动，并且国内的火电市场上的一些新机组在招投标过程中，就明确要求需要具备低压缸切除能力，进而才能获得更多的热电比，提高市场的竞争优势。因此，本文概述切除低压缸运行的风险，详细介绍切除低压缸运行的策略，提出切除低压缸运行风险的预防措施。     

汽轮机轴振抑制方法研究

针对某电厂2号机组发生1号轴振超标问题的诱发原因及振动控制方法开展研究。根据振动响应分析,归纳出转子由于不平衡、不对中及碰摩激振的动力学特性及故障特征。根据处理方案,对高、中压缸进行揭缸处理,检查并调整汽封及通流间隙,消除动静碰摩等因素,并对轴系进行重新找中,经启机后1号轴振超标问题消除。     

压缩机组汽轮机碰磨振动的原因分析

对某大型化工装置的心脏压缩机组汽轮机突发振动异常故障进行诊断,其结果为工作转速下转轴碰磨振动.就其产生的原因进行了分析,并提出相应的改进措施,保证了机组的安全运行.     

支承方式对变循环发动机转子临界转速的影响

分析某双涵道变循环发动机转子系统结构特点,建立转子-支承系统三维有限元模型,计算、分析转子支承方式的改变对转子临界转速的影响.结果表明:以低压转子为主激励,转速在20 000 r/min内,4支点支承比5支点支承临界转速多一阶,其中第一、三阶临界转速降低,第二阶升高,第四阶基本不变.5支点方式能有效地减少柔性低压转子弯曲振动模态出现,但是会增加低压风扇盘的上下偏摆振动模态,较易发生风扇叶片与机匣的碰磨.4支点方式结构更简单,但是转子系统在高转速时需要多经过一阶临界转速,会增加转子及整机的振动.     

双转子发动机转子-机匣碰摩振动特征研究

双转子发动机发生转静碰摩时,会出现高低压转子组合频率(频率和、频率差),但无法区分高、低压转子碰摩。采用简化的动力学模型,讨论双转子发动机转子与机匣碰摩的情况,认为碰摩力往往是一个旋转的力,并对碰摩的三种形式进行了理论分析和数值仿真。发现高压转子发生碰摩时,会出现高压转子的整数倍频NΩH及组合频率NΩH±ΩL的频率成分;低压转子碰摩时,则会出现低压转子的整数倍频NΩL及组合频率NΩL±ΩH的频率成分。组合频率成分在转子上反映并不显著,在机匣的振动响应中则会很突出。开展了双转子碰摩实验研究,实验结果和发动机实测结果均验证了上述结果的正确性。     

浅谈如何防止汽轮发电机组发生弯轴事故

转轴径向碰磨是汽轮机组启动和正常运行中振动突然增大的主要故障之一。为防止汽轮机组产生弯轴和轴系破坏事故,笔者通过剖析产生事故的原因,提出了当转轴存在早期径向碰磨时所应采取的解决方法。     

某型柴油机拉缸故障原因分析与处理

对某型船用主柴油机在修后航行试验过程中出现的拉缸故障停车现象,进行了原因分析和故障排除,恢复了舰船动力设备的性能,保证了修理工程的顺利进行.     

工艺系统弹性变形对发动机镗缸精度的影响

针对工艺系统的弹性变形对发动机镗缸精度的影响进行一些定量的分析和计算 ,为执行合理的发动机大修工艺规程提供依据 ,并改进原镗缸工艺 ,使其达到规定要求     

Interference excitation of a square section cylinder

Wind tunnel experiments were conducted to study the interference excitation of a square section cylinder (test cylinder) and the results are reported in this paper. The study was carried out at some specific relative positions identified between the test cylinder (side dimension B) and the interfering cylinder (side dimension b) so that the latter is never upstream of the former. Experiments were carried out for the b/B ratios of 0.5, 1.0, 1.5 & 2.0. In this paper, emphasis is laid on bringing out the influence of b/B ratio on the vibratory response of the test cylinder, considering a few interference positions. The results show that at a particular relative position, the magnitude of vibrations and the response trend of the test cylinder are markedly influenced by the b/B ratio. Under certain combinations of b/B ratio, relative position and reduced velocity, test cylinder vibrations are considerably magnified and in certain other combinations they are suppressed. Flow visualization results are provided in an attempt to bring out the influence of b/B ratio and also to explain the observed vibratory features of the test cylinder.     

Vortex-Induced Vibrations of a Circular Cylinder at Low Reynolds Numbers

The vortex-induced vibrations of a circular cylinder at low Reynolds (Re) numbers are simulated by applying a method of the two-dimensional computational fluid dynamics coupled with the structural dynamics based on the multi-physics. The fluid solver is first tested on the case of a fixed cylinder at Re≤ l60, and shows a good agreement with the previous high-resolution numerical results. The present study then reports on the detailed findings concerning the vibrations of an elastic cylinder with two degrees of translational freedom for a number of cases in which Re is fixed at 200, a reduced damping parameter Sg=0.01, 0.1, 1.0, 10.0 and the mass ratio M^002A;= 1, 10.     

A novel means of monitoring liner vibrations in diesel engines

A device for monitoring the external corrosion of cylinder liners, electrochemically, is also shown to be a simple means of observing engine liner vibrations.     

大修与新型更新组合优化的蒙特卡罗模拟研究

以采用大修维护的设备为研究对象,以有限时间内维护净收益最大为目标,以更新时机和更新前后大修间隔为决策变量,基于风险控制因素,建立了大修与新型更新的组合优化模型.在此基础上,使用蒙特卡罗模拟方法求解最佳更新时机和新旧设备的最优大修周期,并给出模型求解的方法.算例分析表明了更新前后大修周期的变化,说明了该方法的有效性.     

柴油机缸套磨损故障的机体振动监测研究

研究了柴油机缸套磨损故障的机体振动监测,包括缸套破坏性磨损故障时的机体振动。首先分析了活塞对气缸套的冲击,建立了活塞撞击气缸套侧推力的数学模型,探讨侧推力的大小及作用时间。分析表明,柴油机活塞撞击是机体表面振动的主要激励源。通过模拟试验得知,缸套磨损状态有4种,当缸套间隙正常或中等磨损时,机体振动的增长速度较慢;严重磨损时,振动特征参数值明显增大;如果缸套处于破坏性磨损程度时还继续工作,机体振动则呈指数式增长。这说明机体表面振动特征值的改变可以反映缸套间隙的变化,因此,基于柴油机机体振动对缸套的磨损进行监测是可行的、有效的。     

Simultaneous two-axis vibration measurement of a nonmetallic cylinder by electromagnetic induction and metallic foil loops

This work presents a method based on electromagnetic induction for the simultaneous non-contact measurement of two-axis lateral vibrations of a nonmetallic cylinder. The suggested method employs two pairs of hollow metallic loops, four pairs of permanent magnets and two solenoids. When the cylinder vibrates, eddy currents are generated in the metallic loops due to electromagnetic induction. The current in one pair of loop is induced by the lateral vibration in one direction, while the other by the lateral vibration in the perpendicular direction. The induced currents can be sensed through the remotely installed solenoids. While the proposed technique can be useful for the vibration measurement in hot or insulated cylinders, for which a contact type sensor is hardly applicable, the present study is focused on its underlying measurement mechanism and fundamental experiments. To this end, two-axis vibrations and frequency response functions of a thin nonmetallic cylinder were measured simultaneously by the proposed sensor. They were compared with those extracted by using commercial accelerometers to check the working performance of the proposed measurement technique. The effects of some parameters in the proposed technique, such as the length of the loop, were also investigated.     

Passive increase in driving force in vortex-induced vibration of a semi-hollow cylinder for Reynolds number 200

Journal of Mechanical Science and Technology - We present a semi-hollow body as an effective strategy to increase the driving force for vortex-induced vibrations (VIVs) of a circular cylinder. The...     

Tribological property investigation on a novel pneumatic actuator with integrated piezo actuators

Pneumatic piston–cylinder actuators are commonly used in industry for a variety of automation and robotics applications. In order to suppress leakage, these actuators comprise seal rings which unfortunately introduce friction and affect the positioning accuracy and output force. This article investigates vibrations of the seal generated by integrated piezo actuators to reduce friction force. For this, two piezoelectric stacks are integrated in the cylinder and used to excite vibration modes. This concept was studied in a compact cylinder pneumatic actuator with a bore diameter of 5 mm and a stroke of 10 mm. Dry friction measurement shows a 52% reduction from the original friction force at a driving frequency of 18.29 kHz and vibration amplitude of 0.05 μm. In the wet friction experiments, the friction force can be reduced by 54% from the original wet friction with vibrations at amplitude of 0.04 μm.