The Non-Rotating Annular Test Facility (RPG)

The development and optimisation of new blade profiles for more efficient aircraft engines and power generation turbines requires the comprehensive investigation of aeroelastic phenomena such as flutter and aerodynamically induced blade vibrations. In addition to simulation-based methods, experimental investigations are crucial to deepening our understanding of these phenomena and validating the corresponding theoretical and numerical methods.

With ever-increasing aerodynamic loads on blades, aeroelastic issues are becoming increasingly challenging. Today, these problems affect not only fans and compressors in aircraft engines but also turbines in stationary gas and steam power plants.

With the Non-Rotating Annular Test Facility (Ringgitterprüfstand Göttingen; RPG), the German Aerospace Center (Deutsches Zentrum für Luft- und Raumfahrt; DLR) has a new measurement facility at its disposal for testing the aeroelastic properties of blade profiles and investigating important features of steady flow – such as shock positions – and their influence on aeroelastic behaviour. The facility can also be used to measure configurations that are essential as validation data for the development of numerical methods. Thanks to its excellent accessibility, the test rig also enables the development and qualification of novel measurement techniques, such as optical methods.

A unique feature – easy to instrument and close to reality

There are generally two approaches to aerodynamic and aeroelastic testing of blade profiles. 'Rolled-up' linear cascades are easy to equip with instruments and observe during tests, but don't fully recreate the repeating airflow between individual blade channels in real engines. Ring-shaped rotating grids and measuring systems simulate more realistic flow conditions, but their complex design makes it difficult to install sensors and obtain accurate measurements on the blades.