scholarly journals Single-Coil Eddy Current Sensors and Their Application for Monitoring the Dangerous States of Gas-Turbine Engines

Sensors ◽  
2020 ◽  
Vol 20 (7) ◽  
pp. 2107 ◽  
Author(s):  
Sergey Borovik ◽  
Yuriy Sekisov
Keyword(s):  
Gas Turbine ◽  
Eddy Current ◽  
Natural Aging ◽  
Turbine Engines ◽  
Radial Clearance ◽  
Gas Turbine Engines ◽  
Structural Elements ◽  
Single Coil ◽  
The Impact ◽  
Blade Tips

The creation and exploitation of gas turbine engines (GTE) often involve two mutually exclusive tasks related to ensuring the highest reliability while achieving a good economic and environmental performance of the power plant. The value of the radial clearance between the blade tips of the compressor or turbine and the stator is a parameter that has a significant impact on the efficiency and safety of the GTE. However, the radial displacements that form tip clearances are only one of the components of the displacements made by GTE elements due to the action of power loads and thermal deformations during engines’ operation. The impact of loads in conjunction with natural aging is also the reason for the wear of the GTE’s structural elements (for example, bearing assemblies) and the loss of their mechanical strength. The article provides an overview of the methods and tools for monitoring the dangerous states of the GTE (blade tips clearances, impellers and shafts displacements, debris detecting in lubrication system) based on the single-coil eddy current sensor, which remains operational at the temperatures above 1200 °C. The examples of practical application of the systems with such sensors in bench tests of the GTE are given.

The Potential Impact of Future Fuels on Small Gas Turbine Engines

1982 ◽  
Author(s):  
J. A. Saintsbury ◽  
P. Sampath
Keyword(s):  
Gas Turbine ◽  
Operating Experience ◽  
Gas Turbine Engine ◽  
Turbine Engines ◽  
Gas Turbine Engines ◽  
Turbine Engine ◽  
The Future ◽  
Potential Impact ◽  
The Impact ◽  
Whitney Aircraft

The impact of potential aviation gas turbine fuels available in the near to midterm, is reviewed with particular reference to the small aviation gas turbine engine. The future course of gas turbine combustion R&D, and the probable need for compromise in fuels and engine technology, is also discussed. Operating experience to date on Pratt & Whitney Aircraft of Canada PT6 engines, with fuels not currently considered of aviation quality, is reported.

The Interaction Between Mistuning and Friction in the Forced Response of Bladed Disk Assemblies

1985 ◽  
Vol 107 (1) ◽  
pp. 205-211 ◽  
Author(s):  
J. H. Griffin ◽  
A. Sinha
Keyword(s):  
Gas Turbine ◽  
Turbine Blades ◽  
Forced Response ◽  
Turbine Engines ◽  
Gas Turbine Engines ◽  
Resonant Response ◽  
Friction Dampers ◽  
Bladed Disk ◽  
The Impact ◽  
Slip Force

This paper summarizes the results of an investigation to establish the impact of mistuning on the performance and design of blade-to-blade friction dampers of the type used to control the resonant response of turbine blades in gas turbine engines. In addition, it discusses the importance of friction slip force variations on the dynamic response of shrouded fan blades.

Semi-Closed Gas Turbine Cycles: An Ecological Solution

2001 ◽  
Author(s):  
A. L. Laganelli ◽  
C. Rodgers ◽  
W. E. Lear ◽  
P. L. Meitner
Keyword(s):  
Global Warming ◽  
Greenhouse Gases ◽  
Gas Turbine ◽  
Fossil Fuels ◽  
High Efficiency ◽  
Anthropogenic Heat ◽  
Turbine Engines ◽  
Gas Turbine Engines ◽  
Closed Cycle ◽  
The Impact

The impact on global warming of transportation and the infrastructure that supports it has been investigated over several decades. Anthropogenic heat and the generation of greenhouse gases from burning of fossil fuels and are major contributors to the warming process. An approach to mitigate these effects is discussed that considers semi-closed cycle gas turbine engines as a practical approach to slowing the release of greenhouse gases. Semi-closed cycle gas turbine engines have an inherent capability to reduce all regulated emissions while maintaining high efficiency, which in turn reduces CO2 emissions. With emerging technology development that includes higher component efficiencies, high temperature material development, improved control devices, and advanced combustor designs, aided by computational fluid dynamics, semi-closed cycle engines appear to have the potential to mitigate global warming with little economic or infrastructural impact. A specific semi-closed engine type is described, the high pressure recuperated turbine engine (HPRTE), along with the inherent mechanisms for control of NOx, CO, unburned hydrocarbons, and particulates. Results from a breadboard demonstration of the HPRTE are discussed, as well as emerging technologies which benefit this type of engine.

scholarly journals The eddy-current and ultrasonic investigations of the nickel-base superalloy the gas turbine engine blades after exploitation

2021 ◽  
Vol 2131 (5) ◽  
pp. 052025
Author(s):  
A V Gonchar ◽  
V V Mishakin ◽  
V A Klushnikov ◽  
K V Kurashkin
Keyword(s):  
Gas Turbine ◽  
Eddy Current ◽  
Ultrasonic Waves ◽  
Turbine Engines ◽  
Actual State ◽  
Nickel Base Superalloy ◽  
Gas Turbine Engines ◽  
Eddy Current Method ◽  
Nickel Base ◽  
Base Superalloy

Abstract The work carried out microstructural, eddy-current and ultrasonic studies of the material of spent blades of gas turbine engines made of nickel-base superalloy. To determine the degree of damage to the material of the spent blades, studies of the microstructure were carried out on a scanning electron microscope. It was found that γ' coagulation occurred in some specimens, which corresponds to overheated material. Acoustic studies of the material were carried out using the ultrasonic pulse echo method. Comparative analysis showed that in such specimens there is a significant decrease in the velocity of propagation and attenuation of longitudinal ultrasonic waves. It is found that the readings of the eddy-current flaw detector in overheated specimens differ more than twice in comparison with non-overheated specimens. This fact can be used for operational non-destructive testing of the actual state of the metal structure by the eddy current method with the aim of further safe operation of gas turbine engines.

Predicting the Ultimate Performance of Advanced Power Cycles Based on Very High Temperature Gas Turbine Engines

1993 ◽  
Author(s):  
Paolo Chiesa ◽  
Stefano Consonni ◽  
Giovanni Lozza ◽  
Ennio Macchi
Keyword(s):  
Gas Turbine ◽  
Large Scale ◽  
Computer Code ◽  
Turbine Engines ◽  
Gas Turbine Engines ◽  
Gas Temperature ◽  
Clear Trend ◽  
Performance Improvements ◽  
Future Technology ◽  
The Impact

It is well known that the history of gas turbine engines has been characterized by a very clear trend toward higher and higher operating temperatures, a growth which in the past 40 years has progressed at the impressive pace of approximately 13°C/year. Expected improvements in blade cooling techniques and advancements in materials indicate that this tendency is going to last for long time, leading to firing temperatures of over 1500°C within the next two decades. This paper investigates the impact of such temperature increase on optimal cycle arrangements and on ultimate performance improvements achievable by future advanced gas/steam cycles for large-scale power generation. Performance predictions have been carried out by a modified, improved version of a computer code originally devised and calibrated for “1990 state-of-the-art” gas/steam cycles. The range of performances to be expected in the next decades has been delimited by considering various scenarios of cooling technology and materials, including the extreme situations of adiabatic expansion and stoichiometric combustion. The results of parametric thermodynamic analyses of several cycle configurations are presented for a number of technological scenarios, including cycles with intercooling and reheat. A specific section discusses how the optimum configuration of the bottoming steam cycle changes to keep up with exhaust gas temperature increases. Calculations show that, under plausible assumptions on future technology advancements, within two decades the proper selection of plant configuration and operating parameters can yield net efficiencies of over 60%.

Analysis of High-Speed Cylindrical Roller Bearing With Flexible Rings Mounted in a Squeeze Film Damper

2007 ◽  
Author(s):  
Cyril Defaye ◽  
Daniel Nelias ◽  
Florence Bon
Keyword(s):  
Gas Turbine ◽  
Load Distribution ◽  
High Speed ◽  
Roller Bearing ◽  
Squeeze Film ◽  
Turbine Engines ◽  
Radial Clearance ◽  
Elastic Coupling ◽  
Gas Turbine Engines ◽  
Squeeze Film Damper

For high-precision mechanical systems such as gas-turbine engines, which operate under extreme conditions, it is particularly important to accurately predict the behavior of the mainshaft rolling bearings. This prediction includes, among others, the load distribution, stiffness and power dissipation. Although shaft speeds tend to increase, rings and shaft walls are becoming thinner due to size and weight constraints. Thus, bearing behavior is no longer independent of the housing and ring stiffness. Furthermore, since forty years, the use of squeeze film damper is largely widespread in gas-turbine engines to significantly reduce the vibratory levels. Due to the flexibility of the ring providing the interface between the roller bearing and the fluid film, it appears an elastic coupling which modifies the behavior of the bearing-squeeze film damper system. This paper presents first a squeeze film damper model with a flexible inner ring (i.e. outer ring of the roller bearing). An analytical stop model is introduced to reproduce the interference between the inner ring of the squeeze film damper and its housing. In a second part, an elastic coupling between the presented squeeze film damper model and an existing roller bearing model is proposed. Finally, the results presented show that this coupling has a first order influence on the behavior of the bearing-squeeze film damper system. It is also shown that the coupling between a roller bearing and a squeeze film damper when linked by a flexible ring introduces a dissymmetry of the load distribution with respect to the applied load direction. Moreover, in certain cases, the position of the bearing in its housing can reach eccentricities larger than the radial clearance of the squeeze film damper.

scholarly journals VIBRATION DIAGNOSTICS OF FATIFUE DAMAGE IN STRUCTURAL ELEMENTS OF GAS TURBINE ENGINES AT THE REPAIR STAGE

2021 ◽  
pp. 5-14
Author(s):  
Anatoliy Bovsunovsky
Keyword(s):  
Fatigue Crack ◽  
Gas Turbine ◽  
Vibration Response ◽  
Mode Shapes ◽  
Turbine Engines ◽  
Gas Turbine Engines ◽  
Structural Elements ◽  
Vibration Diagnostics ◽  
Superharmonic Resonance ◽  
Long Time

Vibration diagnostics of damage belongs to the class of non-destructive methods, which usually do not take long time. However, the main problem of vibration diagnostics is relatively low sensitivity to the critical damage of fatigue crack type, which arises because of long time accumulation of plastic deformation. To improve the sensitivity and reliability of vibration diagnostics of damage two methods were considered. First method was based on the fact, that a characteristic feature of vibrations of structural elements with fatigue crack is the occurrence of non-linear resonances (sub- and super-harmonic) and significant non-linearity of vibration response at these resonances. Secon one – on the fact, that quite noticeable in certain cases increase of damping characteristic caused by a crack can be observed. Analytical and experimental studies of these methods were carried out as applied to the blades of aircraft gas turbine engines. As a result of the studies, the intensity of change in parameter of super-harmonic resonance and in damping characteristics at different parameters of crack was determined. Besides, the experimental techniques for vibration testing of turbine blades were developed. There was demonstrated, that the sensitivity of both considered methods of vibration diagnostics is several orders of magnitude higher than the sensitivity of conventional methods based on the change in natural frequencies and mode shapes, and they can be effectively used for the diagnostics of blades on the stage of engine repair. All the other conditions being equal, second-order superharmonic resonance demonstrates a higher sensitivity to the presence of cracks than the damping characteristic. The smallest crack with an area of 0.2% considered in the work causes a reliably recorded non-linearity of vibration response at superharmonic resonance of order of 2/1. At this the change of damping characteristic slightly exceeds the error of experiment.

Relative Effects of Velocity- and Mixture-Coupling in a Thermoacoustically Unstable, Partially-Premixed Flame

2021 ◽  
Author(s):  
Ashwini Karmarker ◽  
Jacqueline O’Connor ◽  
Isaac Boxx
Keyword(s):  
Gas Turbine ◽  
Equivalence Ratio ◽  
Premixed Flame ◽  
Turbine Engines ◽  
Gas Turbine Engines ◽  
Real Gas ◽  
Planar Laser ◽  
Partially Premixed ◽  
Partially Premixed Flame ◽  
The Impact

Abstract Combustion instability, which is the result of a coupling between combustor acoustic modes and unsteady flame heat release rate, is a severely limiting factor in the operability and performance of modern gas turbine engines. This coupling can occur through different coupling pathways, such as flow field fluctuations or equivalence ratio fluctuations. In realistic combustor systems, there are complex hydrodynamic and thermo-chemical processes involved, which can lead to multiple coupling pathways. In order to understand and predict the mechanisms that govern the onset of combustion instability in real gas turbine engines, we consider the influences that each of these coupling pathways can have on the stability and dynamics of a partially-premixed, swirl-stabilized flame. In this study, we use a model gas turbine combustor with two concentric swirling nozzles of air, separated by a ring of fuel injectors, operating at an elevated pressure of 5 bar. The flow split between the two streams is systematically varied to observe the impact on the flow and flame dynamics. High-speed stereoscopic particle image velocimetry, OH planar laser-induced fluorescence, and acetone planar laser-induced fluorescence are used to obtain information about the velocity field, flame, and fuel-flow behavior, respectively. Depending on the flow conditions, a thermoacoustic oscillation mode or a hydrodynamic mode, identified as the precessing vortex core, is present. The focus of this study is to characterize the mixture coupling processes in this partially-premixed flame as well as the impact that the velocity oscillations have on mixture coupling. Our results show that, for this combustor system, changing the flow split between the two concentric nozzles can alter the dominant harmonic oscillation modes in the system, which can significantly impact the dispersion of fuel into air, thereby modulating the local equivalence ratio of the flame. This insight can be used to design instability control mechanisms in real gas turbine engines.

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