In the dynamics of turbomachinery the mechanical damping of the blading is in the focus of research for the last decades to improve the dynamic performance in terms of high cycle fatigue issues. Besides that an increased mechanical damping can produce a higher flutter safety margin such that stable operation conditions are achievable in a bigger range. Hence, novel damping techniques are considered besides the well known friction based damping devices. In this paper an extended analysis of the eddy current based damping device for a last stage steam turbine blading presented in GT2009-59593 is conducted. A transient electromagnetic finite element analysis of the eddy current damper is performed and the resulting damping forces are compared to their analytical solution. Parameter studies are carried out and equivalent damping factors are calculated. Furthermore, for the validation of the finite element model a test rig was built which allows for the direct measurement of damping forces when forcing a sinusoidal relative motion. Forced response measurements and simulations are used to demonstrate its dynamic performance and predictability.
Eddy Current Damper for Turbine Blading: Electromagnetic Finite Element Analysis and Measurement Results
Laborenz, J, Krack, M, Panning, L, Wallaschek, J, Denk, M, & Masserey, P. "Eddy Current Damper for Turbine Blading: Electromagnetic Finite Element Analysis and Measurement Results." Proceedings of the ASME 2011 Turbo Expo: Turbine Technical Conference and Exposition. Volume 6: Structures and Dynamics, Parts A and B. Vancouver, British Columbia, Canada. June 6–10, 2011. pp. 847-858. ASME. https://doi.org/10.1115/GT2011-45242
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