Computational study of stall flutter in linear cascades

A. Abdel-Rahim, F. Sisto, S. Thangam

Research output: Contribution to journalConference articlepeer-review

Abstract

Aeroelastic interaction in turbomachinery is of prime interest to operators, designers and aeroelasticians. Operation at off-design conditions may promote blade stall; eventually the stall pattern will propagate around the blade annulus. The unsteady periodic nature of propagating stall will force blade vibration and blade flutter may occur if the stall propagation frequency is entrained by the blade natural frequency. In this work a computational scheme based on the vortex method is used to simulate the flow over a linear cascade of airfoils. The viscous effect is confined to a thin layer which determines the separation points on the airfoil surfaces. The preliminary structural model is a two-dimensional characteristic section with a single degree of freedom in either bending or torsion. A study of the relationship between the stall propagation frequency and the blade natural frequency has been conducted. The study shows that entrainment, or frequency synchronization, occurs resulting in pure torsional flutter over a certain interval of reduced frequency. A severe blade torsional amplitude (or order 20°) has been computed in the entrainment region reaching its largest value in the center of the interval.

Original languageEnglish
JournalAmerican Society of Mechanical Engineers (Paper)
StatePublished - 1991
EventInternational Gas Turbine and Aeroengine Congress and Exposition - Orlando, FL, USA
Duration: 3 Jun 19916 Jun 1991

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