GB268037A - Improvements in or relating to axial flow hydraulic machines - Google Patents

Abstract

268,037. Gill, J. H. W. Dec. 24, 1925. Impeller blades; casings; regulating. - In axial-flow hydraulic pumps and other apparatus such as hydraulic transmission elements, the rotor blades or the guide vanes (if any) on either or both sides thereof, or both rotor blades and guide vanes, are so shaped that the linear velocity of whirl imparted to the fluid flowing through the rotor is approximately the same at all radii. The preferred arrangement varies the pitch of the pump rotor blades B, Figs. 15 and 16 in a radial direction so as to secure constant whirl at all radii, this in turn giving, with uniform axial-flow velocity, a constant value at all radii for the absolute direc. tion and speed of outflow from the rotor, which enables the outlet guide vanes D to have the inclination of their edges made uniform from root to tip. Fig. 16 shows the cross-section of a rotor blade B at the boss, at the mid-radius, and at the tip, respectively. The axial inlet guide vanes C have their edges C<2> curved slightly in the direction of rotation of the rotor. In a modification, Fig. 19, each outlet guide vane E is mounted in the casing A so as to be rotatable to the desired inclination and then secured by bolts E<4>. A constant whirl rotor F, Fig. 21, may be mounted so that its axial position between the two sets of vanes C, D may be adjusted. This arrangement may also be used with a true screw rotor in which an approximation to constant whirl conditions is obtained by twisting the radial inlet guide vanes so as to produce a forced feed near the axis and a starved feed near the periphery. In a turbine with a constant whirl rotor K, Fig. 22, the inlet guide vanes H are pivoted and controlled simultaneously by a spider J having slots J<1> within which slide pins J<2> on the ends of arms J<3> carried by the vanes. The vanes H may have curved or inclined edges H<1>, H<2>. The inflow passage containing the vanes H may be inclined to the horizontal, and the axial position of the rotor may be adjustable. A reversible tidal turbine, or a reversible pump, is shown in Fig. 24, comprising a rotor O disposel between two sets of balanced wicket vanes Q, R. A series of tangential passages or a single spiral passage may take the place of the adjustable guide vanes, at the turbine inlet or pump outlet. Fixed vanes T<4>, T<5>, T<6>, Fig. 26, may alternate with rotor blades T, T<1> and may be adjustable as described .above. For hydraulic transmission, Fig. 27, two rotors U, U<1> of the constant whirl type rotate in opposite directions, one being connected to the driving shaft U<2> and acting as a pump, whilst the other is connected to the driven shaft U<3> and acts as a turbine. This arrangement has a general application, the second' rotor performing the functions of the guide vanes under all conditions of flow. When the two oppositely running rotors have different pitch, the desired whirl compensation may be obtained by arranging gearing between the two shafts to give the appropriate speeds. Figs. 28 - - 32 show alternative forms of rotor blades V, V<3>, V<6>, V<7> and shrouding V<2>, V<4>, V<5>. In addition to the radial variation in pitch, the rotor blades may be given axial variation in pitch.