A current preliminary design method for flutter of low pressure turbine blades and vanes only requires knowledge of the reduced frequency and mode shape (real). However, many low pressure turbine (LPT) blade designs include a tip shroud, that mechanically connects the blades together in a structure exhibiting cyclic symmetry. A proper vibration analysis produces a frequency and complex mode shape that represents two real modes phase shifted by 90 degrees. This paper describes an extension to the current design method to consider these complex mode shapes. As in the current method, baseline unsteady aerodynamic analyses must be performed for the 3 fundamental motions, two translations and a rotation. Unlike the current method work matrices must be saved for a range of reduced frequencies and interblade phase angles. These work matrices are used to generate the total work for the complex mode shape. Since it still only requires knowledge of the reduced frequency and mode shape (complex), this new method is still very quick and easy to use. Theory and an example application are presented.
Flutter of Low Pressure Turbine Blades With Cyclic Symmetric Modes: A Preliminary Design Method
- Views Icon Views
- Share Icon Share
- Search Site
Kielb, R, Barter, J, Chernysheva, O, & Fransson, T. "Flutter of Low Pressure Turbine Blades With Cyclic Symmetric Modes: A Preliminary Design Method." Proceedings of the ASME Turbo Expo 2003, collocated with the 2003 International Joint Power Generation Conference. Volume 4: Turbo Expo 2003. Atlanta, Georgia, USA. June 16–19, 2003. pp. 423-428. ASME. https://doi.org/10.1115/GT2003-38694
Download citation file: