Abstract: Inside a single casing the turbopump comprises a main shaft driven by a turbine, a secondary shaft coaxial with the main shaft, a low pressure impeller mounted on the secondary shaft to create a medium pressure flow which is brought back to flow parallel to the axis of the turbopump by a baffle and which is deflected through 180.degree. in a return channel so as to come back parallel to the axis of the turbopump towards a high pressure impeller mounted on the main shaft inside the secondary shaft. The entire HP centrifugal flow formed by the HP impeller is output via the insides of fixed hollow blades forming a portion of the baffle towards a delivery channel secured to the casing and collecting the high pressure fluid after it has passed through the fixed hollow blades. A shunt channel is taken from the delivery channel to apply a high pressure centripetal flow through the insides of the curved hollow blades forming a portion of the LP impeller, thereby establishing driving torque for the LP impeller.

Abstract: A radial active magnetic bearing for supporting a rotary shaft in a casing is provided with at least one back-up bearing constituted by a first ring fast with the rotary shaft and a second ring fast with the casing, the rings being concentric and defining a free space whose length in the radial direction is about one half the length of the mean air gap of the radial magnetic bearing. The first and second rings are preferable anchored, respectively, in the stator laminated ferromagnetic rotor armature and in the stator laminated ferromagnetic stator core of the radial active magnetic bearing which may also provide hydrodynamic effects by pumping fluid into the air gap of the bearing.

Abstract: A turbopump with active magnetic suspension comprises at least two back-up bearings, each constituted by a first ring fast with a rotary shaft and a second ring fast with a casing, the rings being concentric and defining a free space whose length in the radial direction is about half the length of the means air gap of the radial magnetic bearings. The first and second rings are preferably anchored, respectively, in the rotor laminated ferromagnetic armature and in the stator laminated ferromagnetic core of a radial active magnetic bearing which may also provide hydrodynamic effects by pumping fluid into the air gap of the bearing.