The influence of neighboring blade rows on the unsteady aerodynamic response of cascades
- Duke Univ., Durham, NC (United States). Dept. of Mechanical Engineering and Materials Science
In this paper, the authors present an analysis of the unsteady aerodynamic response of cascades due to incident gusts (the forced response problem) or blade vibration (the flutter problem) when the cascade is part of a multistage fan, compressor, or turbine. Most current unsteady aerodynamic models assume the cascade to be isolated in an infinitely long duct. This assumption, however, neglects the potentially important influence of neighboring blade rows. They present an elegant and computationally efficient method to model these neighboring blade row effects. In the present method, they model the unsteady aerodynamic response due to so-called spinning modes (pressure and vorticity waves), with each mode corresponding to a different circumferential wave number and frequency. Then, for each mode, they compute the reflection and transmission coefficients for each blade row. These coefficients can be obtained from any of the currently available unsteady linearized aerodynamic models of isolated cascades. A set of linear equations is then constructed that couples together the various spinning modes, and the linear equations are solved via LU decomposition. Numerical results are presented for both the gust response and blade vibration problems. To validate the model, the authors compare their results to other analytical models, and to a multistage vortex lattice model. They show that the effect of neighboring blade rows on the aerodynamic damping of vibrating cascades is significant, but nevertheless can be modeled with a small number of modes.
- Sponsoring Organization:
- USDOE
- OSTI ID:
- 438782
- Report Number(s):
- CONF-950629--
- Journal Information:
- Journal of Turbomachinery, Journal Name: Journal of Turbomachinery Journal Issue: 1 Vol. 119; ISSN JOTUEI; ISSN 0889-504X
- Country of Publication:
- United States
- Language:
- English
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