Erosion Of Thermal Barrier Coatings

Author : Rohan Swar
Publisher :
ISBN 13 :
Total Pages : 76 pages
Book Rating : 4.:/5 (51 download)

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Download or read book Particle Erosion of Gas Turbine Thermal Barrier Coating written by Rohan Swar and published by . This book was released on 2009 with total page 76 pages. Available in PDF, EPUB and Kindle. Book excerpt: The purpose of this research is to examine and understand the complex phenomenon associated with the particle impacts on turbine blades and the associated erosion of Thermal Barrier Coated (TBC) turbine vane and blade surfaces by ingested solid particle impacts. Both experimental and computational techniques were used to find out the parameters relevant to rebound characteristics of particles and erosion rate of TBC coatings.--In the experimental study, tests were conducted in the erosion wind tunnel facility at University of Cincinnati for TBC coated and uncoated blade materials to determine the erosion rates and particle restitution characteristics under different impact conditions. Particle Image Displacement Velocimetry (PIDV) technique was used to determine particle rebound characteristics for different impact conditions. From the experimental results, empirical erosion rate models and restitution coefficient models for Alumina particles impacting on TBC coated blade surface are developed using non-linear regression analysis technique to predict the erosion rate and restitution coefficients for various impact conditions.--In the computational analysis, numerical simulations were conducted for the three-dimensional flow field and particle trajectories through a high pressure single stage axial gas turbine. The solution to the Reynolds Averaged Navier Stokes (RANS) equations for turbulent compressible flow were obtained numerically using ANSYS CFX solver for unsteady N-S equations in their conservation form. In gas turbine applications generally the particle loadings that are encountered are sufficiently low hence a one-way gas-particle interaction model was used to simulate the particle dynamics involved. This does not take into consideration the effects of dispersed particles' momentum exchange with the gas flow field.--The experimentally based particle surface restitution models were incorporated in the simulations to determine particle rebound conditions after each surface impact. The computed particle surface impact statistics were combined with experimentally based erosion models to predict the stator vanes and rotor blades coated surface erosion pattern and intensity.--The experimental results reveal that the erosion rate increases with increase in impingement angle, impact velocity, and temperature. The trajectories are determined for 26 [mu] m and 500 [mu] m alumina particles. The simulation results show that the particle velocity in the stator is reduced by the surface impacts, which causes the particles to enter the rotor with negative incidence compared to the flow. The rotor impacts reduce the particle velocities in the rotating frame, but could increase their absolute velocity. Inertia dominates the 500 [mu] m particle trajectories that reenter the stator row after rebounding from the rotor leading edge impacts. The simulation results predicted the intensity and pattern of TBC erosion over the stator and rotor blade surfaces and the variation in the overall blade surfaces erosion with ingestion velocity.