Session: 22-02 Compressor Aerodamping, Forced Response, and Mistuning

Paper Number: 151262

Experimental and Numerical Investigation of Blade Loading Influence on Aerodynamic Damping in an Axial Compressor 

The market needs for larger plant output and higher efficiency have increased. In order to meet the continuous demand of the market, the compressor of power generation gas turbine becomes longer, thinner blades, and operates in higher Mach number condition.  These increases the risk of blade vibration problem, and more accurate aeroelasticity prediction is needed.

The present research is focused on validating CFD prediction at various operating points, including near stall conditions. The data has been acquired in a closed-loop axial compressor test rig that allows investigating the aerodynamic damping of isolated or embedded compressor rotors. In the current paper, the focus lies on an isolated rotor. In order to measure the aerodynamic damping as accurately as possible, the rotor is manufactured as a blisk such as to reduce the structural damping, and blade vibration is measured by Blade Tip Timing (BTT) to eliminate mistuning coming from measurement sensors. The blisk is excited by electromagnets from the hub, so the flow field is not influenced by blisk excitation. Frequency sweep excitation was conducted around the blisk eigenfrequencies, and the total damping was evaluated from the blade vibration amplitudes. The aerodynamic damping is determined from test data acquired at several pressure levels. The dataset acquired in this test facility is of high quality and high level of detailing, which makes it suitable for CFD validation.

The investigated compressor is operated at subsonic condition. The rotation speed is 20800rpm, and tip Mach number is around 0.8. The damping measurements were conducted along this speed line, from near choke to near stall. The compressor speed line, inlet and outlet flow field were predicted well by CFD. CFD predictions showed good agreement with the measured aerodynamic damping. Using the validated CFD predictions, comparisons of the aerodynamic loading at various operating point and their influence on aerodynamic damping are performed providing further insights on aeroelasticity.

Presenting Author: Toshihiko Azuma Institute of Thermal Turbomachinary and Machinery Laboratory

Presenting Author Biography: 2014.3: Bachelor of Engineering, The University of Tokyo
2016.3: Master of Engineering, The University of Tokyo
2016.4-2024.7: Mitsubishi Heavy Industries, Ltd., Research & Innovation Center
2024.8: University of Stuttgart, Institute of Thermal Turbomachinary and Machinery Laboratory

Authors:

Toshihiko Azuma University of Stuttgart, ITSM
Maiken Günther University of Stuttgart, ITSM
Daniel Nagel University of Stuttgart, ITSM
Yuto Terauchi Mitsubishi Heavy Industries, Ltd
Damian M. Vogt University of Stuttgart, ITSM