Stall flutter

There are three distinet stall phenomena. Rotating stall and individual blade stall are aerodynamie phenomena. Stall flutter is an aeroelastie phenomenon. 

This phenomenon is caused by self-excitation of the blade and is aero-elastic. It must be distinguished from classic flutter, since classic flutter is a coupled torsional-flexural vibration that occurs when the freestream velocity over a wing or airfoil section reaches a certain critical velocity. Stall flutter, on the other hand, is a phenomenon that occurs due to the stalling of the flow around a blade. 

Blade stall causes Karman vortices in the airfoil wake. Whenever the frequency of these vortices coincides with the natural frequency of the airfoil, flutter will occur. Stall flutter is a major cause of compressor blade failure. 

Blade flutter and rotating stall are problems encountered in the compressor due to poor design or contamination of the blades. Changing blade angles can usually solve the problem however, this adjustment is very... 

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