Condition monitoring of aircraft by quantitative filter debris analysis

Various condition monitoring techniques are used collectively to monitor the health of aircraft engines and transmission, a concept known as Integrated Health Monitoring (IHM). A well-established quantitative technique is Aircraft Oil Analysis (AOA), in which spectroscopic techniques such as Rotating Disk Electrode Atomic Emission Spectroscopy (RDE-AES) are employed to analyse periodic oil samples for wear debris. Usually, no sample preparation is undertaken, as the oil sample containing both dissolved and suspended metallic wear debris is analysed directly. AOA works well for oil-lubricated systems with relatively coarse filtration that allow circulation of the debris and its subsequent abrasive contact with moving components. To avoid this secondary wear, finer filtration is employed on both new and older aircraft. Less wear debris, and thus information, is available in the oil. A technique that quantitatively analyses the wear debris caught on the filter has been developed and is termed Quantitative Filter Debris Analysis (QFDA). Actual oil filters from CF88 Challenger ALF 502L-2C and Hornet F404 engines were obtained in sequence, when possible, prepared by the developed procedure, and analysed with AOA instrumentation. With sufficient results, both normal and abnormal levels of wear rates emerged, as has been recorded and used for AOA. Moreover, trending of the data for sequential samples has demonstrated the capability of GFDA for condition monitoring.     

Monitoring of Wind Turbine Gearbox Condition through Oil and Wear Debris Analysis: A Full-Scale Testing Perspective

Despite the wind industry's dramatic development during the past decade, it is still challenged by premature turbine subsystem/component failures, especially for turbines rated above 1 MW. Because a crane is needed for each replacement, gearboxes have been a focal point for improvement in reliability and availability. Condition monitoring (CM) is a technique that can help improve these factors, leading to reduced turbine operation and maintenance costs and, subsequently, lower cost of energy for wind power. Although technical benefits of CM for the wind industry are normally recognized, there is a lack of published information on the advantages and limitations of each CM technique confirmed by objective data from full-scale tests. This article presents first-hand oil and wear debris analysis results obtained through tests that were based on full-scale wind turbine gearboxes rated at 750 kW. The tests were conducted at the 2.5-MW dynamometer test facility at the National Wind Technology Center at the National Renewable Energy Laboratory. The gearboxes were tested in three conditions: run-in, healthy, and damaged. The investigated CM techniques include real-time oil condition and wear debris monitoring, both inline and online sensors, and offline oil sample and wear debris analysis, both onsite and offsite laboratories. The reported results and observations help increase wind industry awareness of the benefits and limitations of oil and debris analysis technologies and highlight the challenges in these technologies and other tribological fields for the Society of Tribologists and Lubrication Engineers and other organizations to help address, leading to extended gearbox service life.     

A review of condition monitoring and fault diagnosis for diesel engines

Technical advances and environmental legislation in recent years have stimulated the development of a number of techniques for condition monitoring and fault diagnosis (CMFD) in diesel engines. This paper firstly summarises common faults, fault mechanisms and their effect on diesel engine performance. Corresponding measurands are presented. Standard CMFD methods for parameters and CMFD systems for diesel engines are reviewed. Finally, some advanced CMFD techniques, including neural networks and fuzzy logic, which may be more powerful, are discussed.     

ASTM D6224四个版本的变化对在用油监测的启发

研究ASTM D6224油液监测标准的98、02、09和16四个版本的变化,主要体现在:(1)在引言中,16版本删除了前三个版本均有的"在用油液监测可使润滑油和装备的服役期最大化",保留了"在用油液监测可确保监测装备以安全、可靠和好的费效比运行";(2)确定的报警值有变化;(3)增加了测量项目和新的测量方法。结合油液监测目前的技术水平和积累的实践经验,提出对我国在用油监测的四点启发:(1)需要制定油液监测单个参数测量的标准方法,一个参数可允许有不同的测量方法;(2)可以根据工程需要,将分析方法分为现场和实验室两类,以更好地指导实践;(3)可将单个参数的监测标准融入到设备状态的判别标准中;(4)需要积极探索适合在用油监测新的有效方法。     

基于油液分析和时间序列模型的内燃机磨损状态监测方法

提出了一种基于油液分析和时间序列模型的内燃机磨损状态监测方法。将整个内燃机看作一个摩擦学系统,利用时间序列模型对摩擦学系统进行动态建模,建立能够表征内燃机磨损状态的数学模型。采用该模型对内燃机润滑油中各元素的变化趋势进行趋势分析,并应用实例对模型进行了检验。结果表明,该方法准确判断内燃机的磨损状态,为内燃机磨损状态监测提供了一种新的途径。     

利用铁谱分析技术对柴油机磨合期的研究

论述了铁谱分析技术的基本原理、方法,阐述了铁谱分析技术的操作流程,通过对农用490BPG型柴油机磨合试验中的产生的机油颗粒物进行分析,准确掌握了柴油机的磨合状态和磨合进程。试验表明,该方法可以为预防突发故障的发生和对磨合期内磨损机理的深入研究提供有效的参考依据。     

掠出射X射线荧光分析技术与掠入射X射线荧光分析技术

依据工作原理,比较了掠出射X射线荧光分析技术(GEXRF)和掠入射X射线荧光分析技术(GI-XRF)的优缺点,比较角度包括实验装置、探测限、可探测元素范围、基体效应以及实验精度.比较结果表明,GEXRF的优点体现为:对实验装置要求低,对轻元素(4＜Z＜20)特别灵敏,能对大样品进行检测,实验精度高;缺点体现为:临界厚度小,探测限高."对轻元素特别灵敏"的特点决定了GEXRF的应用领域将主要集中在化学元素微量和痕量分析以及半导体工业中Si薄膜表面轻元素检测等方面.     

Condition monitoring of steam turbine-generator through contamination analysis of used lubricating oil

The objective of this paper is to present a systematic analysis of wear particles contained in used lubricant of steam turbine-generator of a thermal power station. The turbogenerator was condition-monitored over a period of two years through wear debris and particulate contamination analysis of the oil. Various sophisticated techniques such as automatic particle counter, ferrography, inductively coupled plasma atomic emission spectrometry (ICPAES), scanning electron microscopy and energy dispersive X-ray analysis (SEM/EDAX) have been employed to extract the relevant information about the health of the machine. Eventually, a correlation of different techniques of wear debris monitoring on the basis of current investigation ascertains the significance of the collective approach of various techniques to avoid catastrophic breakdowns and expensive component replacements.     

Statistical study of organomolybdenum compounds in an engine oil formulation and the results of engine testing

Organomolybdenum compounds are versatile lubricant additives of interest in the design of engine oils to meet the new ILSAC (International Lubricant Standardization and Approval Committee) GF‐3 performance standard, especially for fuel efficiency. In this work, organomolybdenum and 13 other components were studied by experimental design and statistical analysis to determine their effects on friction, wear, and oxidation properties. The resulting linear model was used to construct a trial engine oil formulation. Engine test results, including some new tests required for ILSAC GF‐3, confirmed some of the strengths of organomolybdenum compounds, as well as their sensitivity to other additives in the formulation.     

Two-phase flow metering of heavy oil using a Coriolis mass flow meter: A case study

The use of Coriolis mass flow metering for two-phase (gas/liquid) flow is an emerging theme of both academic research and industrial application. The key issues are maintaining flow-tube operation, and modelling and correcting for the errors induced in the mass flow and density measurements. Experimentally-derived data is used to illustrate that these errors vary most notably with gas void fraction (GVF) and liquid flow rate, but other factors such as flow-tube geometry and orientation, and fluid properties such as viscosity are also influential. While undoubtedly a universal two-phase flow correction model is the ultimate research goal, there is currently no obvious candidate to explain the range of behaviours observed. This paper describes and demonstrates an empirical methodology that has proven effective in developing good correction models for a given choice of Coriolis flow-tube and flow mixture.

A growing proportion of the world’s oil reserves may be described as “heavy”, implying high density and high viscosity. Of the various metering challenges heavy oil poses, one of the most significant is its ready entrainment of gas, and the difficulties entailed in separating gas from the oil. Accurate two-phase measurement of heavy oil is therefore an especially desirable technical goal.

Trials were carried out at the National Engineering Laboratory (NEL), Scotland on a 75 mm flowmeter using a high viscosity oil. Flowrates from 1 kg/s to 10 kg/s were examined, with gas void fraction (GVF) up to 80%. The resulting models were tested online in a commercial Coriolis mass flow meter and demonstrated good performance for both steady and slugging two-phase flows, with the corrected measurements typically within 1%–5% of the nominal mass flow and density.

Field trials in Venezuela have confirmed the performance of this two-phase solution.

While research continues into the development of a generic two-phase correction, this case study demonstrates that the current state of the art can provide, for economically important fluids, tailored models with good two-phase flow performance.     

转子试验器的应力分析与碰摩故障的研究

利用自主设计开发的的某型发动机模拟试验器再现试车中的某些机械故障和现象,通过振动,力信号和应变的组合测试并结合理论分析识别出与碰摩故障或现象相对应的特征,为进一步实现对发动机工作状态监测与保障试车安全提供了重要依据。     

Using risk analysis and Taguchi’s method to find optimal conditions of design parameters: a case study

Variation in product performance can be seen as a design failure. The fundamental principle of robust design proposed by Taguchi is to improve the quality of a product by minimizing the effect of causes of variation, without totally eliminating the causes. A method of robust design is briefly explained and its application is demonstrated with the help of a case study from Roots Industries Ltd., Coimbatore. This paper describes how the inherent modeling of product and process requirements in key characteristics (KCs) can be used to express and capture the product design intent. KCs are those features which significantly affect product function and performance, or occur when there is variation. A prototype software program (VRM Tool) was developed to house all the critical design data for process optimization and its eventual reuse. We establish a systematic process of identifying, assessing and mitigating risk in the early stage of design for a Windtone class of automobile electric horn, using robust design concept. The results suggest that the proposed robust design method is an efficient, disciplined approach that can assist a product delivery team in designing for a better functional performance and improved reliability of the entire system .     

Numerical analysis of installation effects in Coriolis flowmeters: A case study of a short straight tube full-bore design

A fully coupled, partitioned, numerical model that accounts for fluid–structure interaction is applied for a study of installation effects in a straight-tube Coriolis flowmeter. Three flow disturbance elements positioned at different locations upstream of the measuring tube are considered in the study: a single elbow, closely coupled double elbows out-of-plane, and an orifice. The installation effects are estimated by comparing the mass-flow sensitivities obtained for the disturbed and the fully developed flow conditions in the measuring tube. The interpretation of the installation effects is given by analysing the anti-symmetric fluid forces in the measuring tube. The simulation results show that the magnitude of the installation effect in asymmetrically distorted flows varies for the different circumferential positions of the motion sensors. The sensitivity variations around the circumference of the measuring tube are less pronounced for measuring tubes with a higher circumferential stiffness.The predicted installation effects are also affected by changing the vibration direction of the tube with respect to the disturbance elements.     

A data driven approach for condition monitoring of wind turbine blade using vibration signals through best-first tree algorithm and functional trees algorithm: A comparative study

Wind energy is one of the important renewable energy resources available in nature. It is one of the major resources for production of energy because of its dependability due to the development of the technology and relatively low cost. Wind energy is converted into electrical energy using rotating blades. Due to environmental conditions and large structure, the blades are subjected to various vibration forces that may cause damage to the blades. This leads to a liability in energy production and turbine shutdown. The downtime can be reduced when the blades are diagnosed continuously using structural health condition monitoring. These are considered as a pattern recognition problem which consists of three phases namely, feature extraction, feature selection, and feature classification. In this study, statistical features were extracted from vibration signals, feature selection was carried out using a J48 decision tree algorithm and feature classification was performed using best-first tree algorithm and functional trees algorithm. The better algorithm is suggested for fault diagnosis of wind turbine blade.     

Additive—additive interaction: A study of the ep and AW performance of sulphurised jojoba oil and sulphurised xanthate in the presence of mocontaining friction modifiers

The extreme-pressure (EP) and antiwear (AW) performance of three soluble molybdenum compounds (commercial molybdenum dialkyldithiophosphate, commercial molybdenum dialkyl dithiocarbamate, and synthesised molybdenum dialkyl dithiocarbamate), and two sulphur-containing EP compounds (sulphurised jojoba oil and sulphurised O-stearyl-S-oleyl xanthate) have been studied alone and in combination, using a four-ball tester. The behaviour of the additives in combination has been found to be selective, and dependent on the chemistry and ratio of the additive components. In general, the addition of Mo-type friction modifiers (FM) to sulphurised EP compounds has shown a synergism, of varying order, in their EP and AW properties.     

A study of Si-L and O-K ELNES in plant material: SiO2, Ca- and Zn-silicate in Minuartia

The formation of vacuolar precipitates containing silicon and calcium, as well as the accumulation of metal-silicates in cell walls of Minuartia has been investigated by electron microscopy, energy-dispersive X-ray analysis and electron spectroscopic imaging. The bond state of the elements concerned is examined by analysing energy-loss near-edge structures (ELNES), particularly the Si-L_2,3 and the O-K ELNES. Experimental ELNES results are compared with local densities of unoccupied states calculated by molecular orbital methods and results of XANES calculations.