Investigation and analysis of deterioration in high pressure compressors due to operation

Abstract

Due to environmental and operational effects, the deterioration of all gas path-related jet engine components is a highly influencing parameter leading to an increase in exhaust gas temperature and specific fuel consumption over time. As a particularly strained engine module, the high-pressure compressor (HPC) is prone to a variety of abrasive and deforming effects that are responsible for a considerable part of overall engine performance losses. During HPC overhaul, new airfoils are typically mixed with reused parts whose refurbishment workscopes typically range from “passed inspection” up to “full leading and/or trailing edge restoration” as well as “tip weld repair”. Hence, a wide spread of airfoil geometries with a distinct statistical distribution can be found within an engine after operation. To allow a statistical analysis, a geometric survey on two full ex-service HPC blade sets and an assortment of equivalent new production parts was conducted. The blades were digitalized by a structured-light 3D scanner in conjunction with a photogrammetry system. Based on the measured three-dimensional data, a CAD model was generated for each blade. Afterwards, airfoil sections on different blade heights were analyzed to generate aerodynamic design parameters such as leading and trailing edge geometries (radius and thickness), their maximum profile thickness, their chord length and their stagger angle. By assessing the statistical results of both used and new parts, the effects of manufacture variations and in-service wear on HPC blade geometry can be compared in detail.