Impact of Defects and Damage in Aircraft Engines on the Exhaust Jet

Abstract

The inspection of aero engines is a complex and time-consuming process, often requiring the disassembling of the engine or boroscopic examinations. The development of a method to locate and characterize defects and damage at an early stage, without disassembling the engine would accelerate the inspection process. For that purpose, the spatial density distribution pattern of the exhaust jet of aircraft engines may be measured with the Background Oriented Schlieren method (BOS). The hypothesis is that defects in the hot gas path have a noticeable impact on the density pattern of the exhaust jet. To establish the connection between defects and measurable patterns, in the present paper numerical simulations of an aero engine are performed including three potential defects. Non-uniformities resulting from a burner malfunction, the increase of the radial gap between blade tip and casing as well as burned trailing edges are propagated with only small degree of dispersion through the turbine and reach the engine exit. The paper shows that each considered defect results in a different exhaust density pattern.