Abstract: A multistage turbomachine is disclosed, comprising a casing with a fluid inlet and a fluid outlet and a plurality of stages arranged in the casing. A flow path extends from the fluid inlet to the fluid outlet through the sequentially arranged stages. Each stage is comprised of a rotating impeller and an electric motor embedded in the casing and arranged for rotating the impeller at a controlled rotary speed. Each electric motor comprises a motor rotor, arranged on the impeller and integrally rotating therewith, and a motor stator stationarily arranged in the casing. Pairs of sequentially arranged impellers are configured for rotation in opposite directions.

Abstract: A centrifugal compressor impeller comprises a gas inlet, a gas outlet, and a disc having a plurality of blades extending therefrom. Each blade has a leading edge at the impeller inlet and a trailing edge at the impeller outlet, a blade base extending along the disc between the leading edge and the trailing edge, a blade tip extending between the leading edge and the trailing edge opposite the disc, a pressure side and a suction side. Each blade has a three-dimensional curvature in at least a portion of the surface, adjacent the leading edge. The leading edge has a curved, non-linear profile in a meridian plane. The blade portion has a double-curvature. Each blade has a first metal angle distribution at the blade base, a second metal angle distribution at the blade tip and at least a third metal angle distribution between the blade base and the blade tip.