Novel Method for Evaluating the Aging of Aviation Turbine Engine Oils via High-Temperature Bearing Deposit Tests

Aviation turbine engine oils require excellent thermal-oxidative stability because of their high-temperature environments.High-temperature bearing deposit testing is a mandatory method for measuring the thermal-oxidative performance of aviation lubricant oils,and the relevant apparatus was improved in the present study.Two different commercial aviation turbine engine oils were tested,one with standard performance(known as the SL oil)and the other with high thermal stability,and their thermal-oxidative stability characteristics were evaluated.After 100 h of high-temperature bearing testing,the SL oil was analyzed by using various analytical techniques to investigate its thermal-oxidative process in the bearing test,with its thermal-oxidative degradation mechanism also being discussed.The results indicate that the developed high-temperature bearing apparatus easily meets the test requirements of method 3410.1 in standard FED-STD-791D.The viscosity and total acid number(TAN)of the SL oil increased with the bearing test time,and various deposits were produced in the bearing test,with the micro-particles of the carbon deposits being sphere-like,rod-like,and sheet-like in appearance.The antioxidant additives in the oil were consumed very rapidly in the first 30 h of the bearing test,with N-phenyl-1-naphthylamine being consumed faster than dioctyldiphenylamine.Overall,the oil thermal-oxidative process involves very complex physical and chemical mechanisms.

Controlling secondary flow in high-lift low-pressure turbine using boundary-layer slot suction

The design of high-lift Low-Pressure Turbines(LPTs)causes the separation of the boundary layer on the suction side of the blade and leads to a strong secondary flow.This present study aims to minimize secondary losses through endwall slot suction and incoming wakes in a front-loaded high-lift LPT cascade with Zweifel of 1.58 under low Reynolds number of 25000.Two slotted schemes for the boundary layer of the endwall were designed(Plan A and Plan B),and the effects of suction mass flow on secondary flow were studied.The underlying physics of the endwall boundary layer of the suction and secondary flow under unsteady wakes was discussed.The results show that slot suction at the endwall boundary layer can significantly suppress the secondary flow by removing low-momentum fluids.Plans A and B significantly reduced the secondary kinetic energy by 44.2%and 36.9%,respectively,compared with the baseline cascade at the suction mass flow ratios of 1%.With an increase in the mass flow ratio of suction,the secondary flow was gradually reduced in both Plans A and B.It is more beneficial to control the secondary flow to destroy the intersection of the pressure side and suction side of the horseshoe vortex before it develops into a passage vortex.Under unsteady wakes,the combined effects of incoming wakes and endwall boundary layer suction can further suppress the secondary flow at the suction mass flow ratios of 2%for Plan A,because the positive and negative vorticity inside upstream wakes accelerated the mixing of the main flow and secondary flow and thus increased the energy of secondary vortices.

Diagnosis and Treatment of the Vibration Fault of a Gas Turbine 6300kW

A gas turbine in a certain gas company didn't work normally because of its strong vibration.Although this turbine had been balanced repeatedly at low speed, the vibration amplitude and unbalance weight of the machine changed irregularly. The causes and characteristics of the vibration are discussed. According to the change of the critical speed and the characteristics of vibration, it is found that the vibration is caused by weakness of the tight force on the central rod of the rotor and the oil whirl of the back bearing of the compressor. After clearing these faults and balancing the rotor of the compressor at high speed, the turbine worksnormally again.

Numerical investigation on bowed blades of large meridional expansion Turbine

To improve the performance of the Turbofan engine,several measures should be considered during design process.Such measures,relating to aerodynamic characteristic design,include the maximum enthalpy per stage,the shortest axial length,the minimum blade rows and the highest efficient in design and off design condition.To satisfy theses design characters,the meridian geometry of the engine will be excurvature at a high degree transition part between HP and LP turbines.The study is to investigate the effect of blade bowing on flow loss at blade tip and root of the type of turbine.Such turbine,tending towards separation,with severe secondary flow at the tip and strong radial flow at exit,was simulated by the 3D N-S solver Numerca,and there were several different stacking line bowing schemes in all.The results show that tip negative bowing and root positive bowing is able to weaken radial flow,consequently reduce the flow loss at the tip and root.

Correlation Dimension in Fault Diagnosis of 600 MW Steam Turbine Generator

GP algorithm of correlation dimension computation is ameliorated which overcomes the shortage of traditional one. Improved process of GP algorithm takes the influence of temporal correlative pairs of points on correlation dimension into account and promotes the computational efficiency prominently. Iterative SVD method is applied to remove the influence of noise on the result of correlation dimension. The faults of steam flow turbulence and oil film disturbance which occur in 600 MW Steam Turbine Generator are analyzed and whose correlation dimensions are computed. More distinct quantitative index than FFT is gained to distinguish two faults and it’s of little importance to apply correlation dimension to study the influence of various factors on steam flow turbulence fault for nonexistence of convergent floor in correlation integral curve, which presents a new way to learn the operational function of large capacity steam turbine generator and carry out comprehensive condition monitoring.

Real-Time Electrostatic Monitoring of Wear Debris for Wind Turbine Gearbox

Engineering practice has shown that early faults of gearboxes are a leading maintenance cost driver that can easily lower the profit from a wind turbine operation.A novel oil-lubricated electrostatic monitoring of wear debris for a wind turbine gearbox is presented.The continuous wavelet transform(CWT)is used to eliminate the noises of the original electrostatic signal.The kurtosis and root mean square(RMS)values of the time domain signal are extracted as the characteristic parameters to reflect the deterioration of the gearbox.The overall tendency of electrostatic signals in accelerated life test is analyzed.In the eighth cycle,the abnormal wear in the wind turbine gearbox is detected by electrostatic monitoring.A comparison with the popular MetalScan monitoring is given to illustrate the effectiveness of the electrostatic monitoring method.The results demonstrate that the electrostatic monitoring method can detect the fault accurately.

TCP和T706对航空涡轮发动机润滑油腐蚀磨损性能的影响机理

针对航空涡轮发动机润滑油对涡轮发动机传动系统摩擦副表面造成腐蚀磨损的问题,基于航空涡轮发动机润滑油腐蚀磨损评价方法,利用四球试验机研究了航空涡轮发动机润滑油中添加剂三甲酚磷酸酯(TCP)和苯骈三氮唑(T706)的杂质氯、硫含量对摩擦副腐蚀磨损的影响,并揭示了其影响腐蚀的机理。结果表明:TCP和T706中的杂质氯都引起金属腐蚀磨损,T706中氯对腐蚀磨损的影响大于TCP中氯的影响,是产生腐蚀磨损的主要因素;T706中氯引起的腐蚀主要为电化学腐蚀,而非化学腐蚀;T706中的硫对金属表面腐蚀的影响较复杂,硫含量较低时,易发生浅表腐蚀,硫含量较高时易发生深度腐蚀,形成密集的腐蚀大坑;有机酸不是产生金属腐蚀的主要因素,引入酸捕捉剂对金属腐蚀无明显改善;尿素作为缓蚀剂,可极大改善T706中氯引起的金属腐蚀。

在役风力发电机组变桨轴承高黏润滑油脂附着状态下阵列涡流检测

为实现在役风力发电机组变桨轴承高黏润滑油脂附着状态下轮齿齿面的高效精准检测,采用仿形阵列涡流技术,研究不同线圈排布方式和提离距离对轴承轮齿齿面缺陷检测结果的影响。结果表明:Z字型和复合型线圈排布方式的边缘效应范围不同,复合型仿形探头较Z字型明显缩短;通过检测10.00 mm×0.50 mm×1.00 mm(槽长×槽宽×槽深)人工槽缺陷,得出内、外齿型轴承的提离距离极限分别为1.04 mm和1.43 mm;对在役风机轴承在表面有高黏润滑油脂条件下进行了试验验证,检测缺陷尺寸与位置结果准确,误差小于5%。该研究成果可为变桨轴承轮齿齿面在役状态下的监督检测提供技术支撑及新思路。

Effects of Freestream Turbulence on Bypass Transition of Separated Boundary Layer on Low-Pressure Turbine Airfoils

This paper presents experimental studies on bypass transition of separated boundary layer on low-pressure turbine airfoils,focusing on the effects of freestream turbulence on the transition process.Hot-wire probe measurements are performed on the suction side of an airfoil in the low-pressure linear turbine cascade at several Reynolds number conditions.Freestream turbulence is enhanced by use of turbulence grid located upstream of the cascade.The results of this experimental study show that the location of boundary layer separation does not strongly de-pend on the freestream turbulence level.However,as the freestream turbulence level increases,the size of separa-tion bubble becomes small and the location of turbulent transition moves upstream.The size of separation bubble becomes small as the Reynolds number increases.At low freestream turbulence intensity,the velocity fluctuation due to Kelvin-Helmholtz instability is observed clearly in the shear layer of the separation bubble.At high frees-tream turbulence intensity,the streak structures appear upstream of the separation location,indicating bypass transition of attached boundary layer occurs at high Reynolds number.

涡轮动力模拟器甩油盘热流模型与流场特性研究

甩油盘作为涡轮动力模拟器(TPS)的重要零件,能有效地促进模拟器内循环系统润滑油的回流,提高轴承的润滑性并降低系统温升,为整机安全可靠运行提供了基础性保障。为了解决TPS内循环系统润滑油的回流问题,对TPS甩油盘及其内部循环流道进行了研究。首先,确定了涡轮动力模拟器轴承发热量及散热系数随转速的变化、甩油盘内部流体控制方程和边界条件;然后,构建了一类TPS甩油盘及其内部循环流道的完整内循环热流模型,并对比了轴承处温度仿真结果与实验结果以确保模型的合理性;最后,数值仿真得到了不同转速下内部循环流道的温度场、压力场和速度场。研究结果表明:转速增加能显著引发系统内最高温度上升,甩油盘作用下的内循环流场温度变化较为平稳,典型工况条件下仿真与实验得到的最高温度相对误差最大为12.3%,表明了热流模型的合理性。研究结果对于指导TPS甩油盘结构设计和提高整机运行安全稳定性具有重要的价值。

裂解气压缩机透平油封结焦原因分析及对策

在正常运行过程中,辽阳石化乙烯装置裂解气压缩机透平高低压端轴振动异常波动,通过排查工艺设备等因素,确定油封结焦引起异常振动,在机组检修过程中对高低压端油封结构进行分析,通过在油封处引入隔离氮气,从根本上解决油封结焦问题。

火电厂汽轮机组汽动润滑油泵的设计与应用

目前火电厂汽轮机组投入使用的主轴驱动油泵和电动主油泵系统都不能在紧急情况下实现供油。为了让机组在全厂失电的情况中安全停机,本文通过利用来自锅炉过热器、再热器、旁路等管道中的余热蒸汽,驱动小汽轮机为润滑油系统供能,研究了锅炉停炉余汽汽源的动态特性,计算了汽动油泵的运行时长,最终设计的汽动油泵可以在突发情况迅速启动,保证系统紧急停机过程中各部分油压、油温稳定。

巨型机组下导轴承安装偏差对油膜特性的影响

水电机组在“碳达峰、碳中和”中发挥着非常重要的作用。下导轴承是水电机组轴系的重要组件,用于径向支撑和约束主轴,在水轮发电机运行过程中发挥重要作用。本文建立了考虑喷淋系统的下导轴承整体三维模型,对其油膜润滑性能以及安装偏差对轴承负荷的影响开展研究。分析发现,喷淋系统减少了油箱内的油搅,但瓦块间的润滑油流动是混乱的,损失主要是由瓦块之间的混乱流动所造成。对瓦块均沿径向偏移的偏差模型,随着瓦块沿径向向内偏移,其油膜压力与温度均逐渐升高;对瓦块均向一侧偏移的偏差模型,随着瓦块均向x轴正向偏移,压力与温度呈不对称分布,瓦面的最大压力与最高温度随偏差的增加而增加,不平衡径向力随偏差的增加而增加。因此,在下导轴承的安装过程中,必须注意瓦块均布圆周与主轴的同轴度。本研究对提高水轮发电机运行质量、降低运行成本和提高水电站效益具有重要意义,为保障百万千瓦水电机组的稳定安全运行提供参考依据。

某型汽轮滑油泵变工况转速波动较大问题

某型汽轮滑油泵在配合系统做变工况试验时,机组转速波动大的问题常有发生。针对这一问题,通过详细分析变工况试验中记录的数据,对可能的问题原因展开分析和排查。初步明确问题发生的原因之后,有针对性地进行试验验证。该问题的研究有助于避免汽轮滑油泵在变工况时发生较大的转速波动,进而保障机组的安全稳定运行。

风电齿轮箱行星齿轮滑动轴承的润滑性能

为研究风电齿轮箱行星齿轮滑动轴承的润滑性能,基于雷诺方程建立了滑动轴承动压润滑性能的计算模型,分析了工况和结构参数对滑动轴承润滑性能的影响。结果表明:在径向载荷和力矩的作用下,滑动轴承的油膜压力主要集中于轴向两端位置;当周向油槽为180°,不考虑修形,且径向载荷发生偏移时,滑动轴承的最大油膜压力增大,最小油膜厚度减小;相较于周向油槽为180°,周向油槽为360°时滑动轴承的承载能力明显降低;当周向油槽为180°时,油膜压力过于集中不利于滑动轴承的正常运行,全圆弧修形能够改善滑动轴承的油膜压力分布。

基于层次分析和熵权法的齿轮油选型评价

针对风力发电机组齿轮箱的安全用油问题,根据风电设备运行特点以及实际运行过程中可能产生的故障,考虑齿轮油基本理化指标、抗污染性能以及极压抗磨性能3个维度,选择9个具体指标,构建涵盖目标层、准则层以及方案层的层次分析(AHP)结构的评价体系;引入熵权法(EWM)的客观赋权,改进综合权重的计算方法,并应用于某风电齿轮箱OEM的油品选型方案中,通过实例验证该方法的有效性与可行性。结果表明,所提出的方法可以实现对风电齿轮油选型结果的量化,有利于快速评价油品性能相关指标,改善了对多油品选择决策过程中主观因素引发的偏差。该方法可为风电齿轮箱油品选择决策提供参考,并可用于其他行业的油品选型决策中,对油品选型具有重要意义。

基础油组成对风电齿轮油VG320性能的影响

风电齿轮油VG320是一种重要的风电主齿轮箱润滑产品,其黏温性能、低温性能、高温性能和润滑性能等通常受基础油组成的影响,表现出明显的差异。本文通过系统考察基础油组成对风电齿轮油核心性能的影响发现,基础油组成对风电齿轮油VG320的黏温性能、布氏黏度、最大无卡咬负荷和抗磨性能方面影响显著。此外,基础油组成对风电齿轮油VG320的倾点和烧结负荷影响相对较小,PAO40的增加,尽管降低了油品的流动性,但对倾点影响不大。

舰用燃气轮机油封装置设计及仿真验证

为了满足不同型号舰用燃气轮机燃油系统及滑油系统的油封需求,设计了一种通用型舰用燃气轮机油封装置。通过更换不同接口型式的供油软管即可实现对不同型号燃气轮机运转或非运转状态下的内部油封。采用理论计算和数值仿真2种方法,分别评估了电加热器将160 L滑油从常温加热至脱水温度的时间,其中,数值仿真的边界条件设置与实际工况更接近,可以代表实际的加热时间。结果表明:采用理论计算和数值仿真方法得到的加热时间为分别为1800、1918 s,二者仅相差118 s(约6.56%),较为吻合,验证了采用理论计算进行电加热器设计选型的有效性;设计的油封装置自动化程度高,可实现循环过滤、加热脱水、冷却保温及油封的一键操作,缩短油封准备时间,极大提高油封效率,同时保证了燃气轮机油封效果,显著延长贮存时间。

新型5 mm^(2)/s级季戊四醇酯航空发动机润滑油基础油性能研究

MIL-PRF-23699G Enhanced Ester(EE)增强酯型润滑油标准是目前航空涡轮发动机润滑油极压承载能力和氧化安定性能的最高标准规范。针对双季戊四醇酯的高温氧化安定性弱于单季戊四醇酯,长链脂肪酸不能同时提高季戊四醇酯的氧化安定性与极压承载性的问题,采用季戊四醇、己二酸、C_(5)~C_(9)一元脂肪酸,通过直接酯化反应合成了一种新型5 mm^(2)/s级季戊四醇酯基础油,相较于单、双季戊四醇酯混合型基础油,新型季戊四醇酯基础油具有更好的黏温性能与低温流动性,其氧化诱导期与Falex失效负荷提升幅度达到20%以上,解决了现有5 mm^(2)/s级多元醇酯基础油合成技术路线中使用双季戊四醇酯、长链脂肪酸无法兼顾两种性能的问题,为下一代EE增强酯型航空发动机润滑油产品的研发提供一定参考。

某FPSO凝析油冲击透平发电机原因分析及解决措施

某浮式生产储卸油装置(FPSO)作为油田群的处理中心,其燃料气系统将处理合格的伴生气供给透平发电机使用。随着上游平台提液增产措施不断取得成效,伴生气组分也随之改变。透平发电机在高负荷运行之下,燃料气消耗量不断增加,燃料气处理系统面临挑战,由于受外界环境温度影响,透平发电机进口燃料气不断有凝析油析出,对透平造成冲击,影响透平正常运行。文章对FPSO燃料气系统处理现状、凝析油析出影响因素进行全面分析,并且提出相应的解决措施,保障了透平发电机的平稳运行。