GB944166A - Rotor for turbines or compressors - Google Patents

Abstract

944,166. Axial-flow compressors and turbines. W. HAUSAMMANN, and R. ISHEROEHLER, [trading as INGENIEUR BUREAU W. HAUSAMMANN & CO.]. March 2, 1960, No. 7457/60. Headings F1C and FIT. A rotor for a compressor or turbine comprises circumferentially spaced blades projecting from a supporting body and each having, in the axial direction of the rotor, at least two parts having different mean camber surfaces, at least one of the mean camber surfaces being a right helicoid the axis of which is the axis of the rotor, or being a surface generated by a line moving so that it is always parallel to and a short fixed distance from the generator of a right helicoid the axis of which is the axis of the rotor, the line lying, in its movement, in successive planes which contain the generator and which are all perpendicular to the axis of the rotor. A right helicoid is defined as surface generated by a straight line which turns about and shifts along an axis which is intersected by the straight line at a right angle, the ratio between turning angle and axial shifting distance being maintained constant. The impeller blades 2, Fig. 3, of an axial-flow compressor or turbine may comprise three parts having mean camber surfaces 7, 8, 9 which are right helicoids of different pitch angles. Alternatively, the blades may comprise two parts only as shown in Fig. 11. Where one part only has a right helicoidal mean camber surface, it is preferably the upstream part. The mean. camber surface of the downstream part may be a substantially continuously curved surface formed of several right helicoids of increasing pitch angle. The lateral external surfaces of the blade may be curved or may each comprise one or more helicoidal surfaces. Each blade may be divided into separate upstream and downstream parts with a gap between them, each part being of aerofoil form and the mean camber surfaces of the two parts being right helicoids of different pitch angle. Preferably, the lateral external surfaces are at least partly right helicoids. The impeller hub may be cylindrical, conical or partly cylindrical and partly conical. Alternatively, the impeller hub may be shaped as described in Specification 812,273 or may be formed with the inclined bulges 104a shown in Fig. 11. The velocity of flow may be supersonic. As shown in Fig. 7a, the mean camber surface may be generated by a line 13a which is spaced at a constant distance d from the generator 13b of a true right helicoid and always lies in the same plane perpendicular to the rotor axis as the generator 13b.