Recently, it has been clarified that unsteady vortical flow field at rotating stall in an axial flow compressor rotor is subject to tornado-type separation vortex linking from the rotor blade suction surface to the casing wall by experimental fluid dynamics and computational fluid dynamics. With the growth of rotating stall, the tornado-type separation vortex rolls up to ahead of the rotor and the vortex leg moves to the midspan from the tip on the blade. Based on these features, the flow mechanism of rotating stall is explained by the three-dimensional separation vortex structure and its interaction with the casing wall and the blade surface.
