T8 – Collaborative Research Centre 871: Regeneration of Complex Capital Goods

T8: Regeneration-induced aeroelastic changes in jet engine turbines

In transfer project T8, the aerodynamic and aeroelastic effects of enlarged radial gaps and varying cooling air parameters on a downstream row of guide vanes and rotor blades are being investigated both experimentally and numerically. Measurements of the unsteady pressure distribution on the housing and guide vanes, as well as the vibration amplitudes of the trailing vanes, provide the basis for modeling and verifying altered excitation mechanisms as a result of the variations.

Motivation

In turbomachinery, the aerodynamics and aeroelasticity of rotor and stator blades are influenced by geometric deviations. Over the service life of a high-pressure gas turbine, e.g., in an aircraft engine, the geometry of the blade tips deteriorates due to high temperatures and abrasive particles present in the flow area. As a result, the radial gaps between the rotor blade and the housing increase, which promotes secondary flow through the gap. This has a direct effect on the unsteady flow field downstream, influencing the structural excitation of the following blade row due to unsteady forces. Wear also changes the geometry of cooling air holes. This leads to variations in local cooling air mass flows and temperatures. These inhomogeneities in the main flow are also a source of excitation for forced vibrations in downstream blade rows. In order to avoid fatigue due to cyclic loading and possible resulting structural damage to the blades, a good understanding of the flow mechanisms that cause these events is essential already during the design phase.

Project Partners

MTU Aero Engines AG

Responsible Institute

The project is managed by the Institute of Turbomachinery and Fluid-Dynamics .