Effects of blade count ratio on aerodynamic forcing and mode excitability
© Copyright 2015 by ASME. The effects of blade count ratio (BCR) on both the steady and unsteady blade loading and the sensitivity of generalized force to a change in mode shape (mode excitability) are studied numerically on two 2D configurations: a subsonic research compressor stage and a turbine stage with supersonic exit. Using the Harmonic Balance method, only a single passage is modeled to represent the actual blade count in a row at a high level of computational efficiency. BCR variation is achieved by scaling the downstream airfoils with a fixed chord-to-pitch ratio, thus preserving the steady-state aerodynamics. It is found that the interaction among potential-, wake-, and shock-related excitations, and the relative strength of harmonic contents are dependent on BCR, resulting in a non-monotonic correlation between unsteady loading and BCR in the downstream row. It is also found that the mode excitability can be sensitive to BCR variation in both up- and downstream rows in some cases. To the best of authors' knowledge, this is the first work on BCR study involving supersonic flow and a discussion of mode excitability patterns.
Proceedings of the Asme Turbo Expo
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International Standard Book Number 13 (ISBN-13)
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