scholarly journals Gas turbine coatings eddy current quantitative and qualitative evaluation

2017 ◽  
Author(s):  
Remo Ribichini ◽  
Carlo Giolli ◽  
Erica Scrinzi
Keyword(s):  
Gas Turbine ◽  
Eddy Current ◽  
Qualitative Evaluation ◽  
Gas Turbine Coatings

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 Development and Testing of a Gas Turbine Engine Foreign Object Damage (FOD) Detection System

2010 ◽  
Author(s):  
D. N. Cardwell ◽  
K. S. Chana ◽  
M. T. Gilboy
Keyword(s):  
Gas Turbine ◽  
Eddy Current ◽  
Engine Speed ◽  
Detection System ◽  
Acoustic Emissions ◽  
Gas Turbine Engine ◽  
Current Sensor ◽  
Foreign Object ◽  
Turbine Engine ◽  
Foreign Object Damage

This paper details the development of a prototype in-flight foreign object damage (FOD) detection system through various stages, resulting in a system capable of detecting objects as small as one gram (1g) mass. The system comprises an eddy current sensor based tip timing system and acoustic emissions vibration sensors controlled through a digital signal processor (DSP). QinetiQ have developed light weight, contamination-immune eddy current tip timing sensors for use in engine health management. Engine tests confirmed these sensors’ potential for detecting FOD events. FOD detection algorithms were developed and implemented in a prototype DSP that was built and tested on an uninstalled gas turbine engine. The trials showed that the prototype DSP FOD detection system could detect dynamic FOD events at full engine speed. Further work was carried out to enhance the FOD detection system, overcoming limitations in the previous system through the implementation of enhanced algorithms and its extension to accept four eddy current sensor inputs as well as a vibration signal input from an acoustic emissions (AE) sensor. An algorithm that computes engine speed from the tip timing data was also implemented to alleviate the need for a separate 1/rev signal. A number of engine trials were successfully completed in order to validate the system. The speed algorithm has been successfully validated on engine trials and comparisons with a conventional optical based 1/rev showed the DSP-generated 1/rev signals to be almost identical to the conventional system. Typically, the error was in the region of 0.03% speed. The investigations culminated in a test series designed to ascertain the system’s sensitivity to foreign object impacts. These demonstrated that the system was capable of detecting objects down to one gram (1g) mass introduced at low speed into the engine intake.

Validation of Multi-Frequency Eddy Current MWM Sensors and MWM-Arrays for Coating Production Quality and Refurbishment Assessment

2003 ◽  
Author(s):  
Vladimir Zilberstein ◽  
Ian Shay ◽  
Robert Lyons ◽  
Neil Goldfine ◽  
Thomas Malow ◽  
...  
Keyword(s):  
Gas Turbine ◽  
Eddy Current ◽  
Coating Thickness ◽  
Bond Coat ◽  
Gas Turbines ◽  
Corrosion Damage ◽  
Operating Conditions ◽  
Ongoing Research ◽  
Metallic Bond ◽  
Thickness Measurements

Coatings for oxidation, corrosion, and thermal protection provide the required materials performance for gas turbine blades and vanes in state-of-the-art industrial gas turbines. These turbines must withstand severe operating conditions for well over ten thousand hours. Variations in the coating thickness, and increased porosity, can influence the lifetime of such coatings significantly. For components that have been removed from service, effective assessment of the aged coating and substrate condition is critical for refurbish/replace/continue-to-run decisions. A suitable device for coating thickness measurement and detection of unacceptable porosity is needed for ensuring the quality of such coatings. In this paper, we present new results on coating thickness measurements for metallic MCrAlY overlay coatings on gas turbine parts. These measurements were performed with a Meandering Winding Magnetometer (MWM®) eddy-current sensor using grid methods. This technique allows proper coating measurements even after a diffusion heat treatment for a better coating adhesive strength. The MWM technology enables measurement of the coating thickness, the absolute electrical conductivity (which may in turn be related to porosity or other properties of interest), and lift-off, which is related to surface roughness. Single-channel MWM sensors and multi-channel imaging MWM-Arrays permit capture of features of interest for a population of components. New capabilities for inspecting gas turbine components are, thus, provided. Inspection applications include metallic and non-metallic coating thickness measurements, porosity measurements, and detection of cracks on complex surfaces. Results of coating assessment for a production line of gas turbine vanes by means of a multifrequency MWM technique are presented for various combinations of coatings and base metals. A description of improved multiple frequency quantitative inversion methods is provided for simultaneous and independent measurement of multiple unknowns such as metallic bond coat thickness, metallic bond coat porosity, and top coat thickness. Ongoing research focuses on characterization of aged components using MWM sensors and imaging MWM-Arrays as well as on development of enhanced algorithms for four and five unknown coating / substrate properties. In a recent study of hot corrosion, uncoated nickel alloy specimens were characterized using an MWM sensor with grid methods. Preliminary results indicated that, within the limitations of the three-unknown single-layer model used, the method could readily identify specimens with no apparent corrosion damage, specimens with moderate corrosion damage, and specimens with severe corrosion damage.

The Use of Eddy Current Sensors for the Measurement of Rotor Blade Tip Timing: Development of a New Method Based on Integration

2016 ◽  
Author(s):  
K. S. Chana ◽  
V. Sridhar ◽  
D. Singh
Keyword(s):  
Gas Turbine ◽  
Eddy Current ◽  
Health Monitoring ◽  
Rotor Blade ◽  
Power Plants ◽  
Service Use ◽  
Low Cost ◽  
Good Alternative ◽  
Blade Vibration ◽  
Current Sensors

The advent of tip-timing systems makes it possible to assess turbomachinery blade vibration using non-contact systems. The most widely used systems in industry are optical. However, these systems are still only used on developmental gas turbine engines, largely because of contamination problems from dust, dirt, oil, water etc. Further development of these systems for in-service use is problematic because of the difficulty of eliminating contamination of the optics. Eddy current sensors are found to be a good alternative and are already being used for gas turbine health monitoring in power plants. Experimental measurements have been carried out on three different rotors using an eddy current sensor developed in a series of laboratory and engine tests in-house to measure rotor blade arrival times. A new tip-timing algorithm for eddy current sensors based on integration has been developed and is compared with two existing tip-timing algorithms: peak-to-peak and peak-and-trough. Among the three, the integration method provided the most promising results in the presence of electrical noise interference. The main aim of this work is to develop an algorithm that can be used to build a simple, robust, real-time and low cost analogue electronic circuit for use in-service health monitoring of engines.

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.

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