TY - GEN
T1 - Analysis and prediction of stall flutter in spanwise finite airfoil cascades
AU - Sisto, F.
AU - Thangam, S.
AU - Chen, T.
PY - 1992
Y1 - 1992
N2 - 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.
AB - 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.
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M3 - Conference contribution
AN - SCOPUS:0026985265
SN - 0791810844
T3 - American Society of Mechanical Engineers, Applied Mechanics Division, AMD
SP - 93
EP - 108
BT - Fundamental Aspects of Fluid-Structure Interactions
T2 - Winter Annual Meeting of the American Society of Mechanical Engineers
Y2 - 8 November 1992 through 13 November 1992
ER -