Aeroelasticity of Fan Blades with Complex Modes
Research into fan blade flutter generally considers structural modes that are pure in either bending or torsion. Reality is often rather different. Real blade modes generally have both bending and torsion components. Moreover, the effect of rotation on large twisted blades induces complex modes, that is modes where the bending and torsion components are not perfectly in-phase.
The aeroelastic stability of complex modes is studied experimentally in a straight cascade wind tunnel in both sub and supersonic flow on a typical fan configuration. Aeroelastic coefficients are measured in the presence of pure plunging and pure pitching as well as complex combinations of these two motions. It is shown that reliable coefficients for complex modes can be obtained by superposition of the coefficients for plunging and pitching. Using the validated principle of superposition, the effect of realistic blade modal parameters on cascade stability is studied.
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- [Sch89]D. Schlaefli. Experimentelle untersuchung der instationaeren stroemung in oszillienden ringgittern. In Thèse de Doctorat. EPF Lausanne, 1989.Google Scholar
- [SF80]E. Széchényi and R. Finas. Aeroelastic testing in a straight cascade wind tunnel. In Proceedings of the 2nd International Symposium on Aeroelasticity in turbomachines. Lausanne, 1980.Google Scholar
- [SG80]E. Széchényi and J.P. Girault. A study of compressor blade stall-flutter in a straight cascade wind tunnel. In Proceedings of the 2nd International Symposium on Aeroelasticity in turbomachines. Lausanne, 1980.Google Scholar
- [Sz80]E. Széchényi. Understanding fan blade flutter through linear cascade aeroelastic testing. In Agardograph 298 vol 1, Ch.X, 1980.Google Scholar
- [HTY80]Y. Hanamura, H. Tanaka and K. Yamaguchi. A simplified method to measure unsteady forces acting on the vibrating blades in a cascade. In Bulletin of the JSME, vol 23, No 180, 1980.Google Scholar