Failure Analysis of High-Pressure Compressor Blade in an Aero Gas Turbine Engine

Failure of high-pressure compressor rotor blade in an aero gas turbine engine is analyzed to determine its root cause. Forensic and metallurgical investigations are carried out on the blade and failed parts. The failure of the platform ladder is found to the first in the chain of events that led to the compressor blade failure. The mode of failure in the blade is found to be fatigue and has originated from the damaged region on the leading edge caused by dislodgement of platform ladder. The failure has caused extensive damages in high-pressure compressor module and also in downstream turbine blades as a secondary effect.     

Failure Analysis of Nozzle Guide Vane of a Low Pressure Turbine in an Aero Gas Turbine Engine

Failure of low pressure turbine nozzle guide vane (NGV) in an aero gas turbine engine is analyzed to determine its root cause. Forensic and metallurgical investigations are carried out on the NGV failed as well as the failed components of the downstream modules. Failure in the cooling system in the NGV due to crack in the sealing plate was found to be the cause of NGV getting burnt. This failure has caused extensive damages in low pressure turbine modules. Remedial measures are also suggested to prevent such failures.     

Fatigue Failure of LP Compressor Blade in an Aero Gas Turbine Engine

Failure of low-pressure compressor rotor blade in an aero gas turbine engine is analyzed to determine its root cause. Forensic and metallurgical investigations are carried out on the blade failed. The failure of the first stage rotor blade is found to be the first in the chain of events that led to the engine failure. The mode of failure in the blade is found to be fatigue and has originated from the mounting lug fillet region due to high stress concentrations. The failure has caused extensive damages in low-pressure compressor module and also in downstream modules as a secondary effect. Remedial measures are also suggested to prevent such failures.     

Analysis of Low-Pressure Turbine Nozzle Guide Vane Failure in an Aero Gas Turbine Engine: A Computational Approach

Journal of Failure Analysis and Prevention - Failure of low-pressure turbine nozzle guide vane (NGV) in an aero gas turbine engine is analyzed using computational approach. Breakage in the cooling...     

Application of Direct Metal Deposition Process for Failure Prevention of Oil Pump Gear Shaft in an Aero Engine

Journal of Failure Analysis and Prevention - Direct metal deposition process has been adopted for repair of oil pump gear shaft of an aero engine. The process is first optimized for the specific...     

Stress-Rupture Characterization in Nickel-Based Superalloy Gas Turbine Engine Components

Today’s gas turbine engines utilize high volume fraction gamma prime (γ′) strengthened alloys for turbine airfoils, which typically operate at temperatures greater than ∼0.5T _m of the alloy. At these temperatures and at stresses below yield, time-dependent deformation (creep) of the airfoil can occur and, if left unabated, can result in complete separation of the airfoil. This process is commonly referred to as stress rupture. Insufficient cooling air, unintentional interruptions of cooling air as well as abnormal engine operating conditions are typical causes of stress-rupture failures in gas turbine blade components. Stress-rupture fractures are generally heavily oxidized, tend to be rough in texture, and are primarily intergranular and/or interdendritic in appearance compared to smoother, transgranular fatigue type fractures. Often, gross plastic yielding is visible on a macroscopic scale. Commonly observed microstructural characteristics include creep voiding along grain boundaries and/or interdendritic regions. Internal voids can also nucleate at carbides and other microconstituents, especially in single crystal castings that do not possess grain boundaries. Other signs of overtemperature include partial resolutioning of the γ′ strengthening precipitates, with the remaining volume fraction of γ′ commonly used to estimate blade metal temperatures. This article highlights the visual, fractographic, and metallographic characteristics typically encountered when analyzing stress rupture of turbine airfoils. An erratum to this article can be found at     

A Fast Method to Calculate the Oil Droplet Velocity in Aero Engine Bearing Chambers

The oil droplet velocity in an aero engine bearing chamber can determine the initial film state which is the fundament for lubrication design and heat analysis. This paper studied the droplet motion in a respective aero engine bearing chamber and obtained a fast method to calculate the droplet velocity by an analytical method. Comparing the velocity results calculated by the fast method with those from the literatures by the numerical method under different operating conditions, the method proposed in this paper is confirmed to be fast and reliable. The effects of operating conditions on droplet velocity are obtained at the same time. This study contribute to follow-up research work on droplet deposition properties in aero engine bearing chambers     

航空发动机风扇噪声经验预测方法分析

随着飞机广泛使用的涡轮风扇发动机涵道比的不断提高,风扇噪声在飞机总噪声中占有越来越突出的地位.因此介绍用于预测风扇噪声水平的三种经验模型:Heidmaan模型,Konto-Janardan-Gliebe模型及Hough-Weir模型.编写风扇噪声经验预测方法程序并计算飞机降落过程中某航空发动机风扇的远场噪声水平.三种模型计算结果对比表明,Heidmann模型预测值普遍较大,Hough-Weir模型与上述两种模型趋势稍有不同.     

Investigation of a Bird Strike Incident of a Military Gas Turbine Engine

This paper investigates a bird strike incident of a military gas turbine engine. The jet pipe temperature of the engine shoot up and rotor speed reduced suddenly during takeoff roll. Long flame was noticed from the engine and aircraft crashed at runway end. Forensic analysis of remnants collected from flow passages confirmed the bird ingestion. Blockage of flow passages due to the presence of bird has led to engine surge and high gas temperature resulting in extensive damage of low pressure turbine module. The paper also proposes remedial measures to avoid such bird strikes during flight.     

Filter Debris Analysis for Aircraft Engine and Gearbox Health Management

Oil filters capture a tremendous amount of tribology information about the operation of a machine. Removal and analysis of the filter debris has proved to be an effective tool for engine health management by determining wear modes and observing failure progression providing long lead times for maintenance remediation. The process of manual debris removal and analysis in a laboratory, however, is tedious. An automated filter debris analysis system provides a repeatable process for at-line or laboratory use. The filters are automatically cleaned; the particles are counted and sized utilizing a quantitative oil debris sensor; and the debris is deposited on a patch for automatic analysis by an integral energy dispersive X-ray fluorescence spectrometer. The XRF analysis procedure provides metallurgical analysis and an expert determination of engine condition. The system has been successfully applied to two operational aircraft fleets, the Canadian Forces S-61 Sea King helicopter fleet and the US Navy EA-6B Prowler aircraft fleet. In both applications, significant benefits have been realized. Reprinted with permission from Integration of Machinery Failure Prevention Technologies into Systems Health Management, Proceedings of the 61st Meeting of the Society for Machinery Failure Prevention Technology, Society for Machinery Failure Prevention Technology, 2007, pp. 239–245.     

发动机油底壳的辐射噪声分析及结构优化

油底壳表面辐射噪声占发动机总辐射噪声的24 %左右,已成为降低发动机噪声的重要制约因素。为了降低某油底壳的辐射噪声,通过有限元模型,计算其约束模态,找出油底壳的薄弱位置;进而施加由试验测得的激励,计算油底壳的表面振动加速度。在此基础上,采用边界元法对其进行辐射噪声总声功率级的计算;根据计算结果,对该油底壳进行结构优化,并预测结构优化后的辐射噪声水平。通过优化前后的对比表明：结构优化后约束模态频率有很大的提高,振型也有明显变化,总声功率级降低了1.83 dB (A)。     

某型航空发动机台架试车异常振动故障诊断

基于某型航空发动机机匣实测振动信号的分析和该型发动机结构特点的剖析,对该型发动机某次试车振动异常现象进行了研究。研究结果表明,低压涡轮支承间隙和偏心量差是引起异常振动的主要故障原因。同时表明,结合现代信号处理技术和正确的分析思路,能够较为快速准确地定位故障,避免盲目的分解检查。     

LM5000燃机振动研究

燃气轮机发电机组振动高问题比较常见，原因也比较复杂，通过对LM5000燃气轮机474—142号机组高压压气机振动高进行原因分析，并通过现场动平衡的方法来降低高压压气机的振动。     

Erosion Testing of Coatings for Aero Engine Compressor Components

The results from a comparative study of erosion resistance of various coatings and some material modification treatments for protecting compressor airfoils made of 17-4 PH stainless steel against sand erosion, are presented. Coatings based on either aluminum, nickel or titanium nitride and material modifications by ion implantation and cryogenic treatment were evaluated by dry particle erosion testing in accordance with the ASTM G76-83 Standard Practice, at different angles of impingement (30°, 60° and 90°). The TiN coatings applied by PVD techniques, were found to be the most erosion resistant. All the PVD deposition techniques appeared capable of producing durable coatings, but in degrees that varied with the deposition method and vendor. All the TiN coatings investigated proved more resistant to erosion at a 30° impingement angle. The implications for compressor airfoil applications are discussed.     

基于硅材料的微型气体涡轮机中微型燃烧器的设计和加工

由微型燃烧器、微型压缩机和涡轮组成的微型气体涡轮发动机有望成为微机电系统的能源系统.阐述了一种微型燃烧器的设计和加工.设计时力图增加流路的长度,其目的是减少微型燃烧腔的热损失和有效地对燃料和空气进行预热.该微型燃烧器由7片厚度不同的单晶硅片组成,通过ICP DRIE干刻蚀加工而成.组装后的微燃烧器的样件尺寸为21.5 mm×21.5 mm×4.4 mm,已成功地进行了氢气燃烧实验和测试.该微型燃烧器和转子组合后可以应用于微型气体涡轮发动机,与压电元件组合后可用于微型发电机.     

某燃气轮机压气机叶尖间隙的分析

设计合理的燃气轮机的叶尖间隙,一直是业内人士非常关注的问题.针对中国某改进型燃气轮机的压气机,在综合考虑材料热膨胀的影响、离心载荷作用下的径向应变、叶片轮盘和机匣的材料代用、轴承的游隙、以及弹性支撑等影响因素共同作用的前提下,通过对机组稳态和过渡态运行工况的叶尖间隙计算,最后给出了改进型压气机动/静转子间的安装间隙.