Silica Particle Ingestion Damage Model and Sensors for Turbomachinery

ABSTRACT:A non-destructive optical sensor and a computational model for quantifying and predicting damage caused by silica particle ingestion in gas turbine engines are proposed. The sensor is based on optical coherence tomography (OCT), which in Phase I was shown to be sensitive to infiltration of calcium magnesium alumino-silicate (CMAS) into thermal barrier coatings (TBCs). In Phase II, a refined prototype sensor will be developed and used to measure the extent of CMAS infiltration of a range of test specimens and ex-service turbine blades and vanes. The accompanying model simulates the infiltration of molten CMAS into a porous TBC under non-uniform and transient temperature conditions, including the viscous flow, partial crystallization, and resulting strain of a given molten mineral deposit. The combination of sensor and model allows testing of predictions and subsequent development and use as a decision support tool for evaluation of the remaining life of critical engine components involving TBCs.BENEFIT: The proposed sensor system and damage model together enable predictions of remaining life of turbine blades and vanes that have been exposed to sand and/or volcanic ash environments. The combined product is envisioned to serve as a decision support tool for both military and civilian aircraft maintenance personnel. The envisioned OCT sensor system will be a valuable diagnostic tool for on-wing inspection of in-service engines to obtain non-destructive evaluations of CMAS infiltration level with improved assessments of damage. Researchers could use the diagnostic for rapid and efficient screening of advanced TBCs through non-destructive testing. Validated damage models will enable prediction of CMAS infiltration and crystallization dynamics, which provides a useful tool for testing and evaluation of CMAS mitigation strategies.