Patent ID: 7220106

Claim:
A Francis runner comprising: a crown; a band; and blades extending between said crown and said band such that a leading edge of each of said blades has points of attachment with said crown and said band and a trailing edge of each of said blades has other points of attachment with said crown and said band, said blades defining between themselves channels for flow of liquid and being rotatable with said crown and said band in a direction defined by a linear component (U), and each of said blades has oppositely oriented lateral faces which are spaced equidistant from an imaginary curved median line extending from said leading edge to said trailing edge; wherein an angle (β 24 ) between the direction defined by the linear component (U) of each of said blades and a straight line (Δ 224 ) extending from the median line of each of said blades at said trailing edge thereof, has, at said point of attachment of each of said blades on said band, a value between 20 and 25°.