Darmstadt Open Test Case: Experimental investigation of forced response phenomena in a transonic compressor stage

The modular compressor at the Transonic Compressor Darmstadt test facility at Technical University of Darmstadt enables investigations of prototype BLISK rotors in single or 1.5-stage setups, operating at high-speed conditions. Within the framework of the European funded research project ARiAS (Advanced Research into Aeromechanical Solutions), forced response blade vibration phenomena and underlying fluid-structure-interaction are investigated. For this, the Darmstadt Open Test Case is enhanced with new rig hardware and equipped with additional steady and unsteady instrumentation to perform extensive aerodynamic and aeromechanical tests. To excite a distinct engine order, a variable wake generator module is applied upstream the rotor BLISK containing 3–16 equally spaced symmetric NACA airfoils. One goal is to experimentally characterize the resulting flow features and determine the impact of wake forcing and rotor tip-clearance on blade vibration and aero-damping by performing a parameter study of various configurations and operating conditions. This paper comprises an overview of the ARiAS compressor stage setup, applied instrumentation and performed measurements. It emphasizes the substantial aerodynamic variations induced by different excitation features, while simultaneously highlighting the inherent independence of the measured system damping from these variations across three fundamental resonance crossings.