Conformable Eddy-Current Sensors and Arrays for Fleetwide Gas Turbine Component Quality Assessment

2001 ◽  
Author(s):  
Neil Goldfine ◽  
Darrell Schlicker ◽  
Yanko Sheiretov ◽  
Andrew Washabaugh ◽  
Vladimir Zilberstein ◽  
...  
Keyword(s):  
Quality Assessment ◽  
Gas Turbine ◽  
Eddy Current ◽  
Coating Thickness ◽  
Cold Work ◽  
Work Quality ◽  
Degradation Monitoring ◽  
Turbine Component ◽  
Current Sensors ◽  
Propeller Blades

The conformable Meandering Winding Magnetometer (MWM™) eddy current sensors and MWM-Arrays provide new inspection capabilities for gas turbine components. The sensors provide measurements of coating thickness and absolute electrical conductivity, which can capture features of interest for a population of components, e.g., for tracking fleetwide trends in quality and aging, failure evaluations and correlating failure origins to features of specific fleet population segments. Inspection applications include metallic and nonmetallic coating thickness and porosity measurement, detection of cracks on complex surfaces, imaging and detection of small flaws, thermal degradation monitoring, and cold work quality assessment. For example, the US Air Force uses the MWM for cold work quality control on all of the C-130 propeller blades that go through the Warner Robins ALC. For P-3 and C-130 propeller blades, trend analysis is being performed fleetwide. This paper describes MWM technology advances for absolute property measurements and specific capability demonstrations. Multifrequency quantitative inversion methods used for coating characterization are also used for characterization of process-affected zones, such as shot peen quality or titanium alpha case characterization.

Conformable Eddy-Current Sensors and Arrays for Fleetwide Gas Turbine Component Quality Assessment

2002 ◽  
Vol 124 (4) ◽  
pp. 904-909 ◽  
Author(s):  
N. Goldfine ◽  
D. Schlicker ◽  
Y. Sheiretov ◽  
A. Washabaugh ◽  
V. Zilberstein ◽  
...  
Keyword(s):  
Quality Assessment ◽  
Gas Turbine ◽  
Eddy Current ◽  
Coating Thickness ◽  
Cold Work ◽  
Work Quality ◽  
Degradation Monitoring ◽  
Turbine Component ◽  
Current Sensors ◽  
Propeller Blades

The conformable Meandering Winding Magnetometer (MWM®) eddy current sensors and MWM-arrays provide new inspection capabilities for gas turbine components. The sensors provide measurements of coating thickness and absolute electrical conductivity, which can capture features of interest for a population of components, e.g., for tracking fleetwide trends in quality and aging, failure evaluations, and correlating failure origins to features of specific fleet population segments. Inspection applications include metallic and nonmetallic coating thickness and porosity measurement, detection of cracks on complex surfaces, imaging and detection of small flaws, thermal degradation monitoring, and cold work quality assessment. For example, the U.S. Air Force uses the MWM for cold work quality control on all of the C-130 propeller blades that go through the Warner Robins ALC. For P-3 and C-130 propeller blades, trend analysis is being performed fleetwide. This paper describes MWM technology advances for absolute property measurements and specific capability demonstrations. Multifrequency quantitative inversion methods used for coating characterization are also used for characterization of process-affected zones, such as shot peen quality or titanium alpha case characterization.

Modelling of Coating Thickness, Heat Transfer and Fluid Flow and It's Correlation with the TBC Microstructure for a Plasma Sprayed Gas Turbine Application

1998 ◽  
Author(s):  
P. Nylen ◽  
J. Wigren ◽  
L. Pejryd ◽  
M.-O. Hansson
Keyword(s):  
Heat Transfer ◽  
Fluid Flow ◽  
Gas Turbine ◽  
Coating Thickness ◽  
Spray Deposition ◽  
Temperature History ◽  
Particle Model ◽  
Barrier Coating ◽  
Discrete Particle Model ◽  
Turbine Component

Abstract The plasma spray deposition of a zirconia thermal barrier coating (TBC) on a gas turbine component has been examined using analytical and experimental techniques. The coating thickness was simulated by the use of commercial off-line programming software. The impinging jet was modelled by means of a finite difference elliptic code using a simplified turbulence model. Powder particle velocity, temperature history and trajectory were calculated using a stochastic discrete particle model. The heat transfer and fluid flow model were then used to calculate transient coating and substrate temperatures using the finite element method. The predicted thickness, temperature and velocity of the particles and the coating temperatures were compared with these measurements and good correlations were obtained. The coating microstructure was evaluated by optical and scanning microscopy techniques. Special attention was paid to the crack structures within the top coating. Finally, the correlation between the modelled parameters and the deposit microstructure was studied.

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 Evaluation of Coating Thickness Using Lift-Off Insensitivity of Eddy Current Sensor

Sensors ◽  
2021 ◽  
Vol 21 (2) ◽  
pp. 419
Author(s):  
Xiaobai Meng ◽  
Mingyang Lu ◽  
Wuliang Yin ◽  
Abdeldjalil Bennecer ◽  
Katherine J. Kirk
Keyword(s):  
Eddy Current ◽  
Coating Thickness ◽  
Thickness Measurement ◽  
Eddy Current Testing ◽  
Thickness Variation ◽  
Testing Technique ◽  
Current Testing ◽  
Thin Skin ◽  
Embedded Algorithms ◽  
Lift Off

Defect detection in ferromagnetic substrates is often hampered by nonmagnetic coating thickness variation when using conventional eddy current testing technique. The lift-off distance between the sample and the sensor is one of the main obstacles for the thickness measurement of nonmagnetic coatings on ferromagnetic substrates when using the eddy current testing technique. Based on the eddy current thin-skin effect and the lift-off insensitive inductance (LII), a simplified iterative algorithm is proposed for reducing the lift-off variation effect using a multifrequency sensor. Compared to the previous techniques on compensating the lift-off error (e.g., the lift-off point of intersection) while retrieving the thickness, the simplified inductance algorithms avoid the computation burden of integration, which are used as embedded algorithms for the online retrieval of lift-offs via each frequency channel. The LII is determined by the dimension and geometry of the sensor, thus eliminating the need for empirical calibration. The method is validated by means of experimental measurements of the inductance of coatings with different materials and thicknesses on ferrous substrates (dual-phase alloy). The error of the calculated coating thickness has been controlled to within 3% for an extended lift-off range of up to 10 mm.

scholarly journals Sorghum harvester work quality assessment

2021 ◽  
Vol 786 (1) ◽  
pp. 012030
Author(s):  
A I Ryadnov ◽  
O A Fedorova ◽  
R V Sharipov ◽  
V A Baril
Keyword(s):  
Quality Assessment ◽  
Work Quality
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