Methods of to maintaining turbine discs prone to cracks in bucket attachment dovetails are disclosed. All turbine engines have a compressor to increase the pressure of the incoming air before it enters the combustor. Lets look around inside the compressors of a few different turbine engines. Robert d fisher exxonmobil research and engineering, houston global technology sponsor machinery mr. The 191 rotor with the 3 cracked discs has had the turbine section removed to be able to use on of the good disc. One means is to bleed cooling air back onto the face of the disk. In the past, turbine discs have been made in ferritic and austenitic steels but nickelbased alloys are currently used. Us8240042b2 methods of maintaining turbine discs to. The turbine disks to which the blades are attached are subject to much higher. Crackgrowth simulations were performed by means of a pure fem and a combined femdbem approach for a compressor disc of a gas turbine engine. In this work, the fatigue crackgrowth process in a rotating disk of an aircraft gas turbine engine has been simulated. A blisk is a turbo machine component comprising both rotor disk and blades. Prediction of crack growth from bolt holes in a disc.
Its energy demand and potential plant run length, linked to its volumetric flow, molecular weight, pressure ratio and associated contaminant removal, is a major design element within the entire ethylene unit. Conventional life assessment methods of bladedisc connections of gas turbines are almost based on finite element analysis 5 and the experimental data of. Corrosion pitting of an igt compressor disc top and fluorescent particle indication of a crack at blade attachment dovetail bottom cracking at the inlet air feed slot of a frame fa turbine is shown in figure 4. Probabilistic sensitivities for fatigue analysis of turbine. As the name suggests, gas turbine engine compressors provide the compression part of the gas turbine engine thermodynamic cycle. An improved turbine disk design to increase reliability of aircraft jet engines nasacr5033 an inproved turbine disk n7626201 disk substantially improved the life of the disk. Us8240042b2 methods of maintaining turbine discs to avert. A cncmilled, single piece axial compressor blisk a blisk portmanteau of bladed disk is a turbomachine component comprising both rotor disk and blades. Since this valuable turbo machinery doesnt have a backup, it must run reliably for two to seven years so operators can efficiently and safely m aximize production to meet market demands. Ashutosh vengurlekar exxonmobil research and engineering, singapore mr. Testing of discs of turbine rotors of gas compressors with.
Disk requirement 2nd stage power turbine disk rh engine 2 name. Crack growth rate and lifetime prediction for aviation gas turbine. Testing of discs of turbine rotors of gas compressors with the dye penetrant nondestructive testing technique article in russian journal of nondestructive testing 448. Material performance in compressor discs and turbine. Failure analysis of a gas turbine compressor in a thermal.
Nozzaloy not only shows the highest resistance to crack initiation, but the crack propagation rate is also as low as the base metal. Failure analysis and repair of a catastrophically damaged gas. For the disc geometry studied by meguid, crack propagation took place across. Probabilistic analysis of aircraft gas turbine disk life and reliability matthew e. The vibration response was measured using externally. Apr 06, 2012 lets look around inside the compressors of a few different turbine engines. There are three basic categories of gas turbine engine compressor. Several premature failures occurred in the highpressure section of the compressor due to the fracture of the blade roots. The life to crack initiation was increased from 30,000 cycles to more than 100,000 cycles the cycles to. In the modal analysis study, increasing the depth of the crack leads.
Crack detection, when dealing with the turbine disk and blades, is mostly visual, although structural inspection techniques can be used, such as penetrant methods and others to aid in the inspection. This analysis resulted from an investigation of a compressor disk from a gas turbine engine that contained cracks in one of the 40 blade attachment. Failure analysis of a gas turbine compressor sciencedirect. Turbines can be found in steam, gas, and hydrostatic power plants. The central region of the disk is counterbored on both sides to create the rim, web, and bore regions of a. Failure characterisation of ti6al4v gas turbine compressor blades. Milligan a, a department of metallurgical and materials engineering, michigan technological university, houghton, mi 49931, usa. Fea is used for the analysis and prevention of operation failures of a compressor disk. Compressor disk is fabricated by titanium alloy and surface crack occurs between the disk and blade attachment. Examples of such cases are ge frame 7ea compressor disc cracking, frame 7fa9fa turbine disc airfeed slot and. We take a detailed look at how a compressor rotor is held together in large jet engine. Principal differences between the two types of impellers are size and ducting arrangement. Probabilistic analysis of aircraft gas turbine disk life and.
Cooling air, bled from the compressor, may be used to cool the turbine blades, vanes and discs to allow higher turbine entry gas temperatures for the same turbine material temperatures. Slight pitting caused by the impingement of foreign matter may be blended by stoning and polishing. The subject of the display is storing wind energy by. High frequency fatigue crack propagation behavior of a nickelbase turbine disk alloy s. Yuki nakamura mitsubishi heavy industries compressor corporation, hiroshima japan mr. What is a split compressor system in a turbine engine. The methodology is demonstrated and verified using a multizone probabilistic fatigue analysis of a gas turbine compressor disk analysis considering stress scatter, crack growth propagation scatter, and initial crack size as random variables. All of the turbines wheels are manufactured using the vacuum investment casting process. From my understanding, the great majority of loads imposed upon a compressor or turbine disc will be centrifugal radial loads, which will tend to try and expand the disc radially. Probabilistic analysis of aircraft gas turbine disk life and reliability. An integral part of rfc is the determination of crack initiation and propagation times. Journal of engineering for sustainable buildings and cities.
Material performance in compressor discs and turbine blades. The purpose of this program was to provide an improved turbine disk design which would increase the reliability of aircraft engines. Pratt whitney turbine disk engine 30293 270 threshold 84342 last or completed 31423 at inst. It consists of a single part, instead of an assembly of a disk and individual, removable blades. Preliminary finite element analysis of a compressor disk. Probabilistic sensitivities for fatigue analysis of. Steam turbines are used across the world as a source of power for many different industries.
The fourth stage low pressure compressor lpc disc of the tf30 engine in the flll aircraft was chosen as the first. High frequency fatigue crack propagation behavior of a. In the modal analysis study, increasing the depth of the crack leads to a decrease. In this study, the fatigue crack growth and lifetime prediction of aviation gas turbine engine compressor disks under operating conditions are analyzed. Compressor blading materials for land based gas tur bines special steels until recently, all production blades for compressors are made from 12% chromium. A as the design of the turbomachinary components such as compressor discs, turbine blades, combustion chamber and shafts are complex and efficiency of these components are directly related to the material performance, therefore material selection is of prime. Initiation of cracks in compressor disks made from twophase titanium alloy has occurred in a disk and blade attachment fig.
Blisks may be additive manufactured, integrally cast, machined from a solid piece of material, or made by welding individual blades to a rotor disk. Abstractthe gas turbine is the heart of all modern marine propulsion. Failure analysis of ti6al4v gas turbine compressor blades. Crack growth life assessment on turbine component under. In all of these failures, crack propagation started from a partthrough surface crack defect. High frequency fatigue crack propagation behavior of a nickel. The engine drive shafts, compressor discs, turbine discs, and gear trains are. Strain gauges were essential to the discovery and also explained the other crack pattern was due to loss of aerodynamic damping causing flutter of the 2diameter mode when in compressor. Combustion section inspection part two flight mechanic. In a free turbine the turbine driving the compressor rotates independently of that which powers the propellor or helicopter rotor. Turbine rotor disk health monitoring assessment based on. The experimental work in this study considered a conceptual design of a disk with machined teeth to imitate compressor or turbine blades and provide a cost effective test article to simulate crack initiation and propagation. Compressors, gas turbines, pumps, steam turbines rotating disk vibration interaction resonance.
Turbine engine fan disk crack detection test william j. Evaluation of a gas turbine disk revealed a crack in the blade attachment area. The two principal types of compressors use in gas turbine aircraft engines are centrifugal flow and axial flow. Failure analysis of a gas turbine compressor in a thermal power plant. According to table 1, the crack on the free surface of the compressor disk increased in size from 0. The present study deals with the fatigue analysis of a turbine disc integrated blade and disc for a small gas turbine for a short life application.
Compressor blade vibrations in a gas turbine engine are an important. Fatigue crack growth in a compressor stage of a turbofan engine by. Integrated approach to gas turbine rotor condition. Turbine a turbine is a device that uses shaft work to drive an electric generator. Sep 28, 2015 a gas turbine is an internal combustion engine that converts heat energy of the fuel into mechanical energy via three main elements a compressor, combustor and turbine. The ct disk and small exit duct as well as the large exit duct are removed. Investigation of candidate features for crack detection in fan and turbine blades and disks michelle meier, oleg v. It was shown that a crack was initiated from the disk edge on its interface with the rotor shaft and was propagated under.
Sep 21, 2019 scc is most commonly seen on steam turbine disk blade root attachments. May 05, 2015 most modern passenger and military aircraft are powered by gas turbine engines, also called jet engines. Ge aeroderivative gas turbines design and operating features ge power systems ger3695e 2 ge industrial aeroderivative gas turbine performance characteristics mechanical drive gas turbine ratings output heat rate exhaust flow exhaust temp. A turbine disc has to rotate at high speed in a relatively cool environment and is subjected to large rotational stresses. Aircraft gas turbine engine compressor section aircraft. The aim of this study is to investigate low cycle fatigue crack propagation in a dovetailtype disk and blade attachment in a representative gte turbine compressor disk, with particular emphasis on the effect of the temperature in a rotating disk. Zaretsky national aeronautics and space administration glenn research center cleveland, ohio 445 and richard august nyma, inc. Mistuning in bladed disks due to the presence of a crack or multiple cracks in blades can cause vibration localization about a few blades 8. Variance estimates and confidence bounds of the sensitivity estimates are developed. Sh3072 7282015 remaining due pratt whitney life limit. This enables us to assure that casting flaws such as sink holes, inclusions and cracks are avoided. Static fracture and modal analysis simulation of a gas turbine. Solutions of the sifs under operating loading conditions of the compressor disk are then implemented into the proposed crack propagation model.
This wind turbine driven air compressor is part of a display at the science museum of minnesota. Every wheel is subjected to xray testing and crack examination. Integrated approach to gas turbine rotor condition assessment and life management. These elements were brought together to simulate the conditions that led to the.
Gas turbine compressor blades are an integral component to a gas. Crackdetection experiments on simulated turbine engine. In one embodiment, wherein a turbine disc comprises a plurality of bucket attachment dovetail regions, one or more of the bucket attachment dovetail regions comprises a cooling slot, and each cooling slot comprises edges and adjacent surfaces, a method comprises inspecting the one or more of. Damage accumulation of a turbine blade is subjected to static load. The subsequent effort to understand the origin of this crack led to a series of analyses that included computing the stresses on the attachment, characterization of fatigue crack growth, and a model for fretting fatigue crack growth. Elliott compressors for worldscale ethylene plants.
Preliminary finite element analysis of a compressor disk in the tf30 engine j. The role of the turbine blisk in a gas turbine is to expand the hot gases. Resolving one of the more serious issues, that of stress corrosion cracking, can often be achieved in a straightforward manner by accurately identifying the causes. What is the typical way the compressor and turbine disks connected to lphp shaft. The pri mary objective of the program was to make an analytical study of a novel approach in structural disk design which would improve the life of the. This leads to a safety procedure whereby aircraft engine turbine discs are being retired at a time when one in discs has initiated a short fatigue crack of 0. Turbine blades are usually inspected and cleaned in the same manner as compressor blades. In this study, the failure process of titanium compressor blades of an industrial gas turbine was investigated. This attachment of a dovetail type has the 26 broach angle at the axis of rotation. All elliott compressors and turbines are thoroughly tested before shipment. This article will offer an explanation of minor resonance of disks, bettertermed interaction resonance, and end with a suggestion to be cautious of a special aspect of turbine blading resonance analysis. Crack gas, propylene and ethylene compressor trains from elliott are custom engineered to meet the high volume, high efficiency requirements of todays.
The blades should be examined for tip rub, erosion, impact damage, coating loss, cracks, and shift. Measure the compressor turbine disk and blade assembly tip clearance. In a gas turbine, the ambient air enters the compressor. This kind of rotors i also used in my homemade jet engine. A comparison was made using either 20node isoparametric elements throughout the mesh or with 3d prismatic quarterpoint isoparametric elements just in the crack area.
Functions of compressor section of the aircraft gas turbine engine. The path to improved cracked gas compressor performance. Cracks on the disk necessitate the rejection of the disk and replacement of the turbine rotor. Antoniou airframes and engines division aeronautical and maritime research laboratory dstotr0915 abstract amrl has been developing expertise in finite element analysis fea of engine components, particularly compressor and turbine discs. Lcf test data for two different groups of aircraft gas turbine engine compressor disk geometries were reanalyzed and compared by using weibull statistics.
Pdf static fracture and modal analysis simulation of a gas turbine. Turbine and compressor thermodynamics for engineer. Vibration and crack detection in gas turbine engine compressor. Keywords gas turbine compressor disk failure crack fretting fatigue introduction gas turbines are complex systems of producing power, a large number of which are utilized in the power plants with the aim to generate electric power. Failure analysis and repair of a catastrophically damaged.
What is the equation for the energy balance between turbine, compressor and propeller. The small duct assembly is disassembled to inspect the compressor turbine stator as well as the small duct. A blisk portmanteau of bladed disk is a turbomachine component comprising both rotor disk and blades. The cracked gas compressor cgc is still the most critical unit in the entire ethylene production facility. May 01, 2016 this leads to a safety procedure whereby aircraft engine turbine discs are being retired at a time when one in discs has initiated a short fatigue crack of 0. Failure characterisation of ti6al4v gas turbine compressor. The crackdetection methodology that was recently investigated on the high precision spin rig involved introducing a notch on a simulated turbine engine disk and monitoring its vibration response as the disk was rotated at speeds up to 12 000 rpm. Mesh for crack propagation analysis in the bolt hole of a compressor disc. Gas turbine diskblade attachment crack springerlink. The experimental results showed no metallurgical and mechanical defects for the blade materials. The challenges in life prediction for gas turbine components arise due to their. Even with the best maintenance procedures and preventative maintenance techniques, problems can still arise. How does it all fit together, where does the air go, and how does it work. Crack detection, when dealing with the turbine disk and blades, is mostly visual.
In the past, turbine discs have been made in ferritic and austenitic steels but. Cgc is a five stages centrifugal compressor caustic wash and drying are facilitated between 4th and 5th stage 5th stage is a heat pump for dec3 system where c4 and heavier are removed cgc is driven by a shp steam turbine turbine extracts hp steam while condensing is controlled by cgc power demand. The low alloy steels of steam turbine rotors are susceptible to scc in the presence of hydroxides such as naoh. Static fracture and modal analysis simulation of a gas. There are several different types of gas turbine engines, but all turbine engines have some parts in common. A hcf crack that causes a blade to break off of the disk can damage. One of the latest damages to a gas turbine due to failure of its compressor disk was reported in a 32 mw gas turbine in rei electrical power plant. The compressor turbine disk and blades are visually and dimensionally inspected. Mesh for crack propagation analysis in the bolt hole of a compressor. What is the difference between a turbine and a compressor. My question is, what exactly is this sort of design feature used for in a compressor or turbine disc. Crack growth rate and lifetime prediction for aviation gas. The limiting factor that affects the useful disc life is its resistance to fatigue cracking. The crack morphology of scc on rotor materials is typically always intergranular.
In a gas turbine, the ambient air enters the compressor and passes through the. Fracture analysis of turbine disks and computational. The split compressor system requires two concentric shafts joining the turbine stages to their respective compressors. The bladed disk consists of 20 identical equally spaced compressor blades mounted on a disk of outer diameter of 700 mm and inner diameter of 530 mm. Slater z wright state university, dayton, oh 45435 identi cation of fatigue cracks in turbomachinery components is a vital but costly e ort. Preliminary finite element analysis of a compressor disk in. As gas turbines operate in a continuous thermodynamic cycle, they have a higher power density than other types of internal combustion engines.
The geometry of a first stage gas turbine compressor blade is obtained from us patent us 7,520,729 b2 and is used for both the single blade analysis and the bladed disk analysis. Surface crack modelling in an engine compressor disc. Remaining turbine section parts are available incliding one row 2 turbine disc which was crack free. Model fuel shp kws btuhphrkjkwhr lbs kgs deg f deg c. The tf41a1b engine is an axial flow gas turbine engine with a round fixedgeometry inlet, fivestage, lowpressure compressor, including a threestage low. Tips for keeping this workhorse in top flight condition.
Investigation of candidate features for crack detection in. Relative creep capability of titanium al loys used for compressor parts in the form of a larson miller plot schematic. During the expansion work will be done by the fluid to drive, for example, electric generation. Macro and microfractographic investigations were carried out on the fracture surfaces. Based on the normal service operation of the compressor, the centrifugal and shear forces applied to the bladedisc configuration were considered in the model. Turbine blades are susceptible to damage and crack formation in regions of component contact that experience both centrifugal and oscillatory vibrations garcia and grandt, 2005. Brook park, ohio 44142 abstract two series of lowcyclefatigue lcf test data for two different groups of.
Causes and resolution of stress corrosion cracking in. Aexplain what material properties are relevant to reliable material performance in compressor discs and turbine blades. Jun 19, 20 here you see how to make a compressorturbine blade. The rotor skid has been modified for transport of the compressor section. Probabilistic analysis of aircraft gas turbine disk life.
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