Fan structure

Claim 1

In a turbofan engine having a rotor which is mounted for rotation with respect to a stationary fan case, the improvement which comprises: a plurality of circumferentially spaced fan blades extending radially from the rotor toward the fan case wherein each fan blade has an inward region which is contoured for the conversion of dynamic energy within subsonic and low supersonic streams to pressure energy and an outward region which is contoured for the conversion of dynamic energy within a high supersonic stream to pressure energy within a subsonic stream and wherein said contour of the outward region is adapted to form between each pair of adjacent blades a convergent passage for the gradual deceleration of the supersonic stream and a throat downstream of the convergent passage for containment of a normal shock wave between adjacent blades; a mid-span shroud positioned on each blade to separate said inward subsonic and low supersonic region from said outward high supersonic region; and at least one starting and stabilizing door in said stationary case which is radially opposes the fan blade tips and which is moveable with respect thereto to vary the area of the convergent passage and of the throat for positioning the shock wave at the throat.