The Non-Rotating Annular Test Facility

The Non-Rotating Annular Test Facility
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The Non-Rotating Annular Test Facility Göttingen is used to investigate the aeroelasticity of turbomachinery blades. The interaction of aerodynamics with structural dynamics is investigated by controlled vibration of the blades in so-called annular cascades. The data gathered enable the improvement of the physical understanding of current and future aeroelastic questions as well as the reliability of numerical aeroelastic methods.

Special features

Compared to more complex test facilities with rotating blade rows, the special feature of the RPG is the stationary test model (annular cascade): The rotation of the test model is replaced by a pre-swirl in the inflow so that the flow conditions are almost the same as in a typical axial turbomachine (no centrigual loads). Without the rotation, the blades can be equipped more extensively with measurement sensors and the data acquisition is eased. This improves the data resolution as well as the data quality.

General data

  • Location: Institute of Aeroelasticity, Göttingen
  • Task: Aeroelastic investigations (flutter, aerodynamic excitation) of compressor and turbine blades.
  • Design and initial operating location : Ecole Polytechnique Fédérale de Lausanne

Technical data

  • Test section for annular cascades with sub- trans- and supersonic compressor or turbine blading
  • Outer diameter of the measuring section: 400 mm
  • Blade height: 40 mm 
  • Max. inlet Mach number: 1.3 for compressor cascades
  • Max. outlet Mach number: 1.7 for turbine cascades
  • Max. mass flow: 12 kg/s
  • Max. pressure ratio: 3 bar
  • Investigations of non-rotating annular cascades: realistic blade (7) inflow conditions thanks to radial-axial deflection with pre-swirl in the radial nozzle (5,6)
  • Electromagnetic excitation of the blades into controlled vibrations with constant frequency, magnitude and phase
  • Aerodynamic probe measurement up- and downstream the annular cascade
  • Simple instrumentation of the annular cascade and easier data acquisition (no cable rotation necessary)
  • Aerodynamic excitation and blade response measurements (forced response) by optional rotating struts added upstream of the annular cascade
Principle sketch of the Non-Rotating Annular Test Facility Göttingen

Application areas

  • Development and optimization of new blade profiles to increase energy efficiency of aircraft engines and power generation turbines
  • Aeroelastic investigations of blade profiles for aircraft engines and stationary gas and steam turbines
  • Flutter investigations of compressor and turbine airfoils
  • Investigations of aerodynamic excitation and forced vibration response of turbine and compressor airfoils
  • Steady-state and unsteady blade pressure surface distribution measurements on the airfoil surfaces using built-in pressure sensors (improved spatial resolution possible due to non-rotating conditions), blade vibration measurements using displacement transducers
  • Optical flow measurements and visualization through simple and permanent optical accessibility (no trigger needed at a specific rotation position)
Department

Aeroelastic Experiments

The department “Aeroelastic Experiments” is committed to the planning, realization and analysis of challenging experiments in wind tunnels.

Contact

Dr. rer. nat. Holger Mai

Head of Aeroelastic Experiments
German Aerospace Center (DLR)
Institute of Aeroelasticity
Bunsenstraße 10, 37073 Göttingen
Germany