Effects of surface roughness and nonparallelism on the measurement of the acoustic nonlinearity parameter in steam turbine blades

2000 ◽  
Author(s):  
Jeong K. Na
Keyword(s):  
Surface Roughness ◽  
Steam Turbine ◽  
Turbine Blades ◽  
Nonlinearity Parameter ◽  
Acoustic Nonlinearity Parameter ◽  
Acoustic Nonlinearity ◽  
Steam Turbine Blades

Decomposition Method to Detect Fatigue Damage Precursors in Thin Components Through Nonlinear Ultrasonic With Collinear Mixing Contributions

2020 ◽  
Vol 3 (2) ◽  
Author(s):  
Gheorghe Bunget ◽  
Stanley Henley ◽  
Chance Glass ◽  
James Rogers ◽  
Matthew Webster ◽  
...  
Keyword(s):  
Fatigue Damage ◽  
Crack Nucleation ◽  
Second Harmonic ◽  
Turbine Blades ◽  
Nonlinearity Parameter ◽  
Decomposition Technique ◽  
Acoustic Nonlinearity Parameter ◽  
Acoustic Nonlinearity ◽  
Nonlinear Ultrasonic ◽  
Short Time

Abstract Cyclic loading of mechanical components promotes the formation of dislocation substructures in metals as precursors to crack nucleation leading to final failure of the metallic components. It is well known within the ultrasonic community that the acoustic nonlinearity parameter is a meaningful indicator of the microstructural damage accumulation. However, current nonlinear ultrasonic techniques suffer from response saturation and limited resolution after 50% fatigue life of the metallic medium. The present study investigates the feasibility of incorporating collinear wave mixing interactions into second harmonic assessments to improve the sensitivity of the nonlinear parameter to a microstructural accumulation of damage precursors (DP). To this end, a decomposition technique was explored to obtain higher harmonics from short time-domain pulses propagating through thin metallic components such as jet engine turbine blades. The results demonstrate the effectiveness of the decomposition technique to measure the acoustic nonlinearity parameter as an early and continuous indicator of fatigue damage precursors throughout the service life of critical aircraft components. A micrographic study showed a strong correlation between the nonlinearity parameter and the increase in damage precursors throughout the life of the specimens.

Diagnostics and monitoring of the operating condition of steam-turbine blades

2007 ◽  
Vol 41 (5) ◽  
pp. 295-301
Author(s):  
A. I. Danilin ◽  
S. I. Adamov ◽  
A. Zh. Chernyavskii ◽  
M. I. Serpokrylov
Keyword(s):  
Steam Turbine ◽  
Turbine Blades ◽  
Operating Condition ◽  
Steam Turbine Blades

Water-droplet erosion behavior of high-velocity oxygen-fuel-sprayed coatings for steam turbine blades

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Dingjun Li ◽  
Peng Jiang ◽  
Fan Sun ◽  
Xiaohu Yuan ◽  
Jianpu Zhang ◽  
...  
Keyword(s):  
Steam Turbine ◽  
Water Droplet ◽  
Erosion Resistance ◽  
Turbine Blades ◽  
Impingement Angle ◽  
Erosion Behavior ◽  
Water Droplet Erosion ◽  
Steam Turbine Blades ◽  
Oxygen Fuel ◽  
Sprayed Coatings

Abstract The water-droplet erosion of low-pressure steam turbine blades under wet steam environments can alter the vibration characteristics of the blade, and lead to its premature failure. Using high-velocity oxygen-fuel (HVOF) sprayed water-droplet erosion resistant coating is beneficial in preventing the erosion failure, while the erosion behavior of such coatings is still not revealed so far. Here, we examined the water-droplet erosion resistance of Cr3C2–25NiCr and WC–10Co–4Cr HVOF sprayed coatings using a pulsed water jet device with different impingement angles. Combined with microscopic characterization, indentation, and adhesion tests, we found that: (1) both of the coatings exhibited a similar three-stage erosion behavior, from the formation of discrete erosion surface cavities and continuous grooves to the broadening and deepening of the groove, (2) the erosion rate accelerates with the increasing impingement angle of the water jet; besides, the impingement angle had a nonlinear effect on the cumulative mass loss, and 30° sample exhibited the smallest mass loss per unit area (3) an improvement in the interfacial adhesion strength, fracture toughness, and hardness of the coating enhanced the water-droplet erosion resistance. These results provide guidance pertaining to the engineering application of water erosion protective coatings on steam turbine blades.

Titanium steam turbine blades

JOM ◽  
1989 ◽  
Vol 41 (3) ◽  
pp. 31-35
Author(s):  
R.R. Jaffee
Keyword(s):  
Steam Turbine ◽  
Turbine Blades ◽  
Steam Turbine Blades
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