Uncovering the Root Causes of Stall Flutter in a Wide Chord Fan Blisk

Flutter was encountered at part speeds in a scaled wide chord fan blisk designed for civil aeroengine during rig test when the bypass flow throttled toward its stall boundary. Analysis of blade tip timing measurement data revealed that blades vibrated first flap (1F) mode with nodal diameters two and three. To facilitate further ultimately eliminate flutter problem, numerical campaign launched to help understand root causes flutter. Both influence coefficient method (ICM) traveling wave (TWM) were employed investigation analyze unsteady flows due vibration, intention corroborate different results take advantage each method. nonphysical reflections, sponge layer an inflated mesh size used extended inlet outlet regions. Steady field examined relate them The influences vibration frequency, mass rate, shock, boundary separation acoustic propagation behaviors on stability also investigated. Particular attention paid behaviors.