S. Moffatt
On decoupled and fully-coupled methods for blade forced response prediction
Moffatt, S.; He, L.
Authors
L. He
Abstract
Two highly efficient fully-coupled methods of predicting the resonant forced response of turbomachinery blades have been developed with the intention of increased computational efficiency over a decoupled method. The flow and structural equations are solved simultaneously, based on the frequency-domain nonlinear harmonic method and the modal reduction technique. By combining the aerodynamic forcing and damping calculations into a single analysis, the coupled solution at a single excitation frequency is approximately half that of the decoupled method. Significant flow–structure coupling effects were discovered, leading to a study into the impact of frequency shift on the fully-coupled solution. A case study on the NASA Rotor 67 transonic aero fan rotor shows a significant reduction in vibration amplitude for the fully-coupled solution due to the resonant frequency shift, caused by the aerodynamic added mass effect. Prompting the development of a novel resonance-tracking algorithm to solve the additional degree-of-freedom in resonant frequency, the increase in computational efficiency in the fully-coupled method is lost due to the need for multiple solutions. A study into the added mass effect and the implications on the coupled solution is undertaken and an evaluation is made between the use of decoupled and fully-coupled forced response systems. It is shown that the decoupled method can accurately predict the resonant vibration level from a single calculation at the natural frequency and is insensitive to frequency shift for lightly damped cases.
Citation
Moffatt, S., & He, L. (2005). On decoupled and fully-coupled methods for blade forced response prediction. Journal of Fluids and Structures, 20(2), 217-234. https://doi.org/10.1016/j.jfluidstructs.2004.10.012
Journal Article Type | Article |
---|---|
Publication Date | 2005-02 |
Deposit Date | Feb 16, 2007 |
Journal | Journal of Fluids and Structures |
Print ISSN | 0889-9746 |
Publisher | Elsevier |
Peer Reviewed | Peer Reviewed |
Volume | 20 |
Issue | 2 |
Pages | 217-234 |
DOI | https://doi.org/10.1016/j.jfluidstructs.2004.10.012 |
Keywords | Turbomachinery, Flows. |
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