Analysis and prediction of stall flutter in spanwise finite airfoil cascades

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1 Scopus citations

Abstract

The analysis and prediction of aeroelastic instabilities are of considerable importance in the design of turbomachinery. Stall flutter, one of the most important off-design phenomena, occurs when the airfoils experience flow separation with propagating stall cells. Predictive capability for the onset of stall for known blade geometry and material properties is necessary to avoid blade flutter by design modifications. In this study, the unsteady aeroelastic behavior of the turbomachinery blade cascades is analyzed. A pseudo-three-dimensional representation of the spanwise finite cantilever blades with and without pretwist is used in conjunction with the vortex method to analyze stall flutter. The mutual interaction of the structural displacement and the aerodynamic loading is effectively captured by this algorithm. The three-dimensional results for the spanwise finite airfoil cascades are shown to compare well with those for infinite linear cascades modeled by a two-dimensional characteristic section with a single degree-of-freedom in either bending or torsion. The computational results for a cascade of compressor blades with pretwist show that the bending motion in the direction normal to the chord dominates blade displacement in the fundamental frequency mode. The results also indicate that while entrainment, or frequency synchronization may occur over a certain interval of frequency, the spanwise behavior of the cascade can exhibit considerable variations. The possibility of the second harmonic of the stall frequency exciting the blade at its natural frequency is uncovered.

Original languageEnglish
Title of host publicationFundamental Aspects of Fluid-Structure Interactions
Pages93-108
Number of pages16
StatePublished - 1992
EventWinter Annual Meeting of the American Society of Mechanical Engineers - Anaheim, CA, USA
Duration: 8 Nov 199213 Nov 1992

Publication series

NameAmerican Society of Mechanical Engineers, Applied Mechanics Division, AMD
Volume151
ISSN (Print)0160-8835

Conference

ConferenceWinter Annual Meeting of the American Society of Mechanical Engineers
CityAnaheim, CA, USA
Period8/11/9213/11/92

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