Wheel for a hydraulic machine, a hydraulic machine including such a wheel, and an energy conversion installation equipped with such a hydraulic machine
View Patent ↗The invention relates to a wheel (R) of the Francis type that comprises a ring ( 1 ) with revolution symmetry about the rotation axis (Z) of the wheel (R), and curved blades ( 21, 22 ) connected to the ring ( 1 ) and each having an outer peripheral edge ( 212, 222 ) and an inner central edge ( 211, 221 ). The connection points (B 21 , B 22 ) between the ring ( 1 ) and the inner central edges ( 211, 221 ) of the blades ( 21, 22 ) are located on a same circle (C 20 ) centered on the axis (Z). The connection points (A 21 , A 22 ) between the ring ( 1 ) and the outer peripheral edges ( 212, 222 ) of the blades ( 21, 22 ) are located on at least two distinct circles (C 21 , C 22 ) (D 21 , D 22 ) centered on the axis (Z).
1. A wheel of a Francis type for a hydraulic machine designed to pass a forced flow of water, the wheel comprising:
a band that is circular and symmetrical about an axis of rotation of the wheel;
nine curved blades that extend from the band and each curved blade having an outside peripheral edge and an inside central edge;
the band is connected to the inside central edges of the blades at connection points that are situated on a common circle that is centered on the axis and the band is connected to the outside peripheral edges of the blades at connection points that are situated on two distinct circles that are centered on the axis;
wherein the blades include six long blades and three short blades, the long blades having connection points situated on a first of the two distinct circles, and the short blades being disposed on the band with an angular spacing of 120° and having connection points situated on a second of the two distinct circles having a diameter smaller than a diameter of the first circle.
2. The wheel according to claim 1 , including a crown that is circular and symmetrical about the axis and which crown faces the band, the crown is connected to the inside central edges of the blades at connection points that are situated on a common circle centered on the axis, and the crown is connected to the outside peripheral edges of the blades at connection points that are situated on at least two other distinct circles that are centered on the axis.
3. The wheel according to claim 2 , wherein the other two distinct circles that are centered on the axis include one circle having a first diameter and another circle having a second diameter smaller than the first diameter.
4. The wheel according to claim 2 , wherein the short blades are distributed uniformly about the axis and the long blades are distributed uniformly about the axis.
5. The wheel according to claim 2 , wherein each short blade has a length lying in a range of 50% to 99% of a length of a long blade.
6. The wheel according to claim 5 wherein a length of the short blades is equal to 70% of the length of the long blades.
7. A hydraulic machine, including a wheel according to claim 1 .
8. An energy conversion installation, including at least one hydraulic machine according to claim 7 .