BLADE OF TURBINE WHEEL OF RADIAL-AXIAL (FRANCIS) HYDRAULIC TURBINE Russian patent published in 2003 - IPC

FIELD: mechanical engineering; turbines. SUBSTANCE: blade of turbine wheel of radial-axial (Francis) turbine of curvilinear shape has leading and trailing edges and it is connected by end face surfaces to rim and hub. Leading edge of blade is rectilinear, parallel to axis of wheel rotation. In Decart coordinate system whose axis Z coincides with axis of wheel rotation and axial X lies in meridional plane containing trailing edge of blade, coordinates of middle line x′, y′ and thickness d′ of blade in section plane intersecting coordinate plane XOZ along axis X and arranged at angle of 68^o relative to plane XOZ are found from relationships . Coordinates of middle line x′, y′ and thickness d′ of blade in plane of section passing through point (0; 0; 0,085 D₁), and intersecting coordinate plate XOZ along straight line parallel to axis X and arranged at angle 62^o relative to plane XOZ are defined by relationships . Coordinates of middle line x′, y′ and thickness d′ of blade in plane of section passing through point (0; 0; 0,175 D₁), and intersecting coordinate plane XOZ along straight line parallel to axis X and arranged at angle 55^o relative to plane XOZ are defined by relationships where D₁ - is nominal diameter of wheel, x′, y′ - are coordinates of middle line of section in coordinate plane of section X′OY′, axis X′ parallel to axis X and passing through trailing edge of blade, and axis Y′ corresponds to line intersection of coordinate plane YOZ and blade section plane. EFFECT: improved cavitation characteristics of turbine and increased efficiency. 3 dwg