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Non-Rotating Annular Test Facility Göttingen (RPG)

General data

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

Technical data

Technische Skizze RPG

• Test section for annular cascade with subsonic and transonic 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
• Investigations of non-rotating annular cascade: realistic inlet flow conditions of the blades (7) by radial-axial deflection with pre-swirl in the radial nozzle (5,6)
• Electromagnetic excitation of the blades to controlled oscillations in magnitude and phase
• Aerodynamic probe measurement up and downstream the annular cascade 
• Simple instrumentation of the non-rotating annular cascade 
• Aerodynamic excitation and vibration response measurements (forced response) by optional rotating struts upstream of the annular cascade

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
  • Experimental flutter investigations of compressor and turbine airfoils
  • Experimental investigations of aerodynamic excitation and forced vibration response of turbine and compressor airfoils
• Unsteady pressure distribution measurements on the airfoil surfaces using built-in pressure sensors (improved spatial resolution possible due to non-rotating conditions)
• Optical flow measurements and visualization through simple and permanent optical accessibility (no trigger needed at a specific rotation position)

Literature

• Bölcs, A., 1983. A Test Facility for the Investigation of Steady and Unsteady Transonic Flows in Annular Cascades. ASME Paper 83-GT-34
• Belz, J., Hennings, H., 2006. Experimental Flutter Investigations of an Annular Compressor Cascade: Influence of Reduced Frequency on Stability. K.C.Hall, R.E.Kielb, J.P.Thomas (Eds.): Unsteady Aerodynamics, Aeroacoustics and Aeroelasticity of Turbomachines, Springer, pp.77—91
• Belz, J., Hennings, H., Kahl, G., 2010. Experimental Investigation of the Forcing Function and Blade's Forced Pitching Oscillations of an Annular Compressor Cascade in Transonic Flow. ASME Paper GT2010-23590
• Chenaux, V.A., 2012. Experimental Investigation of the Aeroelastic Stability of an Annular Compressor Cascade at Reverse Flow Conditions. Ecole Polytechnique Fédérale de Lausanne, Thèse No 5358