Deterioration of Thermal Barrier Coated Turbine Blades by Erosion

Abstract

A combined experimental and computational study was conducted to investigate the erosion of thermal barrier coated (TBC) blade surfaces by alumina particles ingestion in a single-stage turbine. In the experimental investigation, tests were performed to determine the erosion rates and particle restitution characteristics under different impact conditions. The experimental results show that the erosion rates increase with increased impingement angle, impact velocity, and temperature. In the computational simulations, an Euler-Lagrangian two-stage approach is used in obtaining numerical solutions to the threedimensional compressible Reynolds-Averaged Navier-Stokes equations and the particles equations of motion in each blade passage reference frame. User defined functions (UDFs) were developed to represent experimentally based correlations for particle surface interaction models and TBC erosion rates models. UDFs were employed in the three-dimensional particle trajectory simulations to determine the particle rebound characteristics and TBC erosion rates on the blade surfaces. Computational results are presented in a commercial turbine and a NASA-designed automotive turbine. The similarities between the erosion patterns in the two turbines are discussed for uniform particle ingestion and for particle ingestion concentrated in the inner and outer 5% of the stator blade span to represent the flow cooling of the combustor liner.

Parametric Study of Scaling Effects on Turbine Blades Thermal Barrier Coating Erosion

“…A physical time scale of 1.5*10 -4 sec was used in the particle trajectory integration. Particle surface interaction modeling was based on experimental measurements obtained by Swar et al 4 for EB-PVD 7YSZ coated INCO718 samples over a range of impact conditions for the alumina particles. A schematic of the particulate flow wind tunnel that was used to conduct the particle rebound tests is shown in Fig.…”

“…Swar et al 4 also developed for experimentally based correlations. The particle velocity and angle restitution coefficients and given in Eq.…”

“…Similarly, Swar et al 4 developed correlations for the EB-PVD 7YSZ TBC erosion rate in the high temperature erosion tunnel over a range of flow temperatures of 1144K (1600F) to 1255K (1800F), particle impact velocities of 122 to 366 m/s and impingement angles of 0 to 90 degrees. Eq.…”

“…Recently, Swar et al 4 measured erosion rates of TBC over a range of particle impact conditions. He also measured particle restitution coefficients over a range of impact angles for coated samples.…”

Effect of Thermal Barrier Coating on the Thermal Stress of Gas Microturbine Blades and Nozzles

“…Gas microturbines (GMT) are small turbomachines that work using gases at high temperatures, with power capacities ranging from 15 kW to 300 kW and offer variable speeds from 30,000 rpm up to 120,000 rpm [1]. They operate with the same operation principle of all the conventional gas turbines; therefore, the efficiency of these devices depends on the gas temperature, which can become higher than 1000 K [2] and [3]. Blades and nozzles of the turbines are subjected to different loads like high temperature, corrosion, centrifugal forces, etc., which could lead to failures [4] and [5].…”