60864 - Instabilities Everywhere! Hard Problems in Aero-Engines 

2021 ASME IGTI Scholar Lecture

Instabilities Everywhere! Hard Problems in Aero-Engines

Z. Spakovszky, Gas Turbine Laboratory, Massachusetts Institute of Technology, Cambridge MA 02139, USA

Many of the challenges that limited aero-engine operation in the 1950s, 60s, 70s and 80s were mostly static in nature: hot components exceeding temperature margins, stresses in the high-speed rotating structure approaching safety limits, and turbomachinery aerodynamic efficiencies missing performance goals. Modeling tools have greatly improved since, mostly due to better computers enabling large simulations of the fluid flow and supporting structure, and have helped enhance jet engine design. The situation is thus different today, where most problems encountered past the design and development phases are dynamic in nature. These can jeopardize engine certification and lead to major delays and increased program cost. A real challenge is the characterization of damping and the related dynamic behavior of rotating and stationary components and assemblies, and of the fluid-structure interactions and coupling. The theme of this lecture is instability in the broadest sense. A number of problems of technological interest in aero-engines are discussed with focus on dynamical system modeling and identification of the underlying mechanisms. Future perspectives on outstanding seminal problems and grand challenges are also given.