Abstract: An axial flow compressor including one or more axially spaced stator sections (14) each having a circumferential array of guide vanes (15), and one or more rotor section (12, 16) each having a circumferential array of rotor blades (13, 17; A, B), and between successive rotor blades (A, B) there are formed flow paths and between the stator and rotor sections there are provided axial gaps (22, 23, 24) of a diverging configuration so as to form in each flow path a diffusion region (C) which extends from a narrowest cross section (a2) of the flow path located at a certain distance upstream of the leading edge of a second rotor blade (B) to a wider cross section (a3) located approximately at the leading edge of the second rotor blade (B), wherein each flow path has a transition region (D) of a substantially non-increasing cross sectional area extending from the wider cross section (a3) to the trailing edges of the rotor blades (A, B).

Abstract: A compressor unit intended for delivering a pressurised gaseous medium at a varying outlet flow volume to a consumer with varying load demands and comprises one or more rotors (K; 10, 11) forming one or more compressor stages and arranged to operate continuously at high speed thereby delivering a certain outlet flow volume, a drive motor (M; 19), a drive line assembly (N; 17, 18) mechanically coupling the compressor rotor or rotors (K; 10, 11) to the drive motor (M; 19), and a waste flow circuit connected to the outlet end of the compressor stages and incorporating at least one power recovery turbine (TR; 22, 23) mechanically coupled to the drive line assembly (N; 17, 18), and one or more valves (V; 25, 34, 35) controlling the waste flow through the waste flow circuit in response to the actual load demand, wherein the power recovery turbine or turbines (TR; 22, 23) are arranged to deliver power back to the drive line or drive lines (N; 17, 18) at consumer load demands smaller than the certain outlet flow volu