Vortex-lift mechanism in axial turbomachinery with periodically pitched stators

Conventional aerodynamic theory of lift is based on the Kutta-Joukowski condition, in which the lift and drag coefficients are predicted basedon the assumption that flow is attached and steady-state. Recent researchoninsect flight indicates, however, that the unsteady motion of a wing can generate much higher unsteady aerodynamic force through the flow induced by the shedding vortices. In the present work, therefore, we propose a novel type of stage consisting of rotor and periodically pitched stator to take advantage of unsteady vortex lift. The numerical results suggest that the flowfield around the leading and trailing edges of the blades are substantially modified by the interactions between the rotor and pitchingstator.Several transientlift peakscanbegenerated foreach period.Ifanappropriate pitchingphaseis chosen for the stator, stage performance can be improved through unsteady lift mechanism effects.