1. Institute for Thermal Turbomachinery and Machine Dynamics, Graz University of Technology, Graz 8010, Austria e-mail:
2. Institute of Jet Propulsion and Turbomachinery, RWTH Aachen University, Aachen 52062, Germany
3. Dipartimento di Macchine, Sistemi Energetici e Transporti, Università di Genova, Genoa 16126, Italy
4. MTU Aero Engines, Munich 80995, Germany
5. Institute for Thermal Turbomachinery and Machine Dynamics, Graz University of Technology, Graz 8010, Austria