Alternate root turbine blading

Claim 2

A rotor for axial flow elastic fluid turbine apparatus comprising: a shaft member having a plurality of axial grooves disposed circumferentially about the periphery thereof and having a surface area thereon, said grooves being a predetermined circumferential distance from each other, a first rooted blade disposed in one of said plurality of axial grooves, said first rooted blade having a platform portion thereon; a second rooted blade disposed in an adjacent axial groove, said second rooted blade having a platform portion thereon,; a rootless blade having a platform portion thereon, said platform portion having an underside sUrface thereon, said underside surface of said platform portion of said rootless blade directly abutting said surface area on said shaft member, said platform portion of said first rooted blade and said platform portion of said second rooted blade contacting said platform portion of said rootless blade to radially secure said rootless blade in position against said shaft member and, means for damping relative motion between said rooted blades and said rootless blade, said means comprising said contacting platform portions adapted so that relative motion between said rooted blades and said rootless blade generates a friction force therebetween to dampen said relative motion.

Claim 3

The rotor of claim 1, further comprising means for axially securing said rootless blade to said shaft member, said axial securing means comprising a slot disposed circumferentially about the periphery of said shaft, and, a pin member extending radially form said underside surface of said rootless blade, said direct abutment between said underside surface of said platform portion of said rootless blade and said surface area on shaft permitting said radially extending pin member to engage said circumferential slot to axially secure said rootless blade to said shaft.

Claim 4

The rotor of claim 1, wherein said first and said second rooted blade each has a root member comprising a radially innermost substantially cylindrical knob portion, a substantially rectanguloid neck portion connected to said knob portion, and a transition portion disposed radially between said knob portion and said neck portion, said transition portion being disposed so as to prevent stresses from concentrating adjacent roots as said roots radially secure said rooted blades to said shaft, said knob portion and said transition portion being completely disposed radially beneath the surface of said shaft, a predetermined portion of said neck being disposed radially beneath said surface of said shaft.

Claim 5

The rotor of claim 1, wherein said platform poriton of said first rooted blade has a laterally extending protrusion thereon, said platform portion of said second rooted blade has a laterally extending protrusion; and, said platform portion of said rootless blade has a first lateral protrusion thereon and a second lateral protrusion thereon, the underside surface of said platform portion of said rootless blade and the underside portions of said lateral protrusions of said rootless blade directly abut said rotor shaft, said lateral protrusion of said first rooted blade contacting said first lateral protrusion of said rootless blade, said lateral protrusion of said second rooted blade contacting said second lateral protrusion of rootless blade, contact between said rootless blade and said first rooted blade and said second rooted blade radially secures said platform portion of said rootless blade in the abutting relationship with said rotor.

Claim 6

The rotor of claim 4, wherein said lateral protrusions on said first and said second rooted blades each have a smooth surface on the underside thereof, said lateral protrusions on said rootless blade each have a smooth surface on the radially outer side thereof, said smooth underside surfaces of said lateral protrusions of said first and said second rooted blades overlapping and contacting against said smooth radially outer surfaces on said lateral protrusions of said rootless blade, said relative motion between said rooted and rootless blades generating said friction force along said overlapped and contacted smooth surfaces on said platforms of rooted blades and said rootless blade to dampen said relative motion therebetween.

Claim 7

A rotor for an axial flow, elastic fluid turbine apparatus comprising: a shaft member having a plurality of axial grooves extending radially into said shaft and arranged circumferentially about the periphery thereof, said grooves defining a predetermined surface area of said shaft therebetween, a first and a Second blade having a root thereon, each root being disposed in adjacent axial grooves, each root having a predetermined circumferential dimension at the point on said root radially adjacent said surface of said shaft, said first and said second rooted blades each having a platform portion thereon spaced radially outward from said roots, said platforms each having a first and a second lateral protrusion thereon, the circumferential dimension on each blade between edges of said lateral protrusions being greater than said predetermined circumferential dimension of said root, said protrusions being spaced radially away from said shaft surface, each protrusion having a smooth underside surface thereon, said first protrusion on said first rooted blade and said second protrusion on said second rooted blade each circumferentially overlapping a portion of said surface area between said first and said second rooted blades, and, a rootless blade disposed between said first and said second rooted blades, said rootless blade having a platform portion having a first and a second lateral protrusion thereon, the greatest circumferential dimension of said rootless blade being disposed across said lateral protrusions, said platform portion of said rootless blade having a smooth underside surface thereon, said lateral protrusions of said rootless balde having smooth radially outer surfaces thereon, said underside surface of said rootless blade platform directly abutting against said surface of said shaft between first and said second rooted blades, said smooth, radially outer surface of said first protrusion of said rootless blade being radially beneath and overlapped by said smooth underside surface of said first lateral protrusion on said first rooted blade, said smooth radially outer surface of said second protrusion on said rootless blade being radially beneath and overlapped by said smooth, underside surface of said second lateral protrusion on said second rooted blade, the smooth underside surfaces of said lateral protrusions of said rooted blades overlapping, contacting and abrading against the radially outer surfaces of said lateral protrusions of said rootless blade to radially secure said rootless blade to said rotor, said rooted blades and said rootless blade being adapted so that relative motion between said rootless and said rooted blades generates a friction force between said smooth overlapping, contacting and abrading surfaces to dampen said relative motion between said rooted blades and said rootless blade.

Claim 8

A rotor for an axial flow, elastic fluid turbine apparatus comprising: a shaft member having a plurality of axial grooves extending radially into said shaft and arranged circumferentially about the periphery thereof, said grooves defining a predetermined surface area of said shaft therebetween, a first and a Second blade having a root thereon, each root being disposed in adjacent axial grooves, each root having a predetermined circumferential dimension at the point on said root radially adjacent said surface of said shaft, said first and said second rooted blades each having a platform portion thereon spaced radially outward from said roots, said platforms each having a first and a second lateral protrusion thereon, the circumferential dimension on each blade between edges of said lateral protrusions being greater than said predetermined circumferential dimension of said root, said protrusions being spaced radially away from said shaft surface, each protrusion having a smooth underside surface thereon, said first protrusion on said first rooted blade and said second protrusion on said second rooted blade each circumferentially overlapping a portion of said surface area between said first and said second rooted blades, and, a rootless blade disposed between said first and said second rooted blades, said rootless blade having a platform portion having a first and a second lateral protrusion thereon, the greatest circumferential dimension of said rootless blade being disposed across said lateral protrusions, said platform portion of said rootless blade having a smooth underside surface thereon, said lateral protrusions of said rootless balde having smooth radially outer surfaces thereon, said underside surface of said rootless blade platform directly abutting against said surface of said shaft between first and said second rooted blades, said smooth, radially outer surface of said first protrusion of said rootless blade being radially beneath and overlapped by said smooth underside surface of said first lateral protrusion on said first rooted blade, said smooth radially outer surface of said second protrusion on said rootless blade being radially beneath and overlapped by said smooth, underside surface of said second lateral protrusion on said second rooted blade, the smooth underside surfaces of said lateral protrusions of said rooted blades overlapping, contacting and abrading against the radially outer surfaces of said lateral protrusions of said rootless blade to radially secure said rootless blade to said rotor, said rooted blades and said rootless blade being adapted so that relative motion between said rootless and said rooted blades generates a friction force between said smooth overlapping, contacting and abrading surfaces to dampen said relative motion between said rooted blades and said rootless blade.

Claim 9

The rotor of claim 6, wherein said root portion which radially secures said first and said second rooted blade to said shaft comprises a substantailly cylindrical knob portion; a substantially rectanguloid neck portion connected to said knob portion, and, a transition portion disposed radially between said knob portion and said neck portion, said knob portion being the radially innermost portion of said root when said root is disposed in one of said adjacent axial grooves, said predetermined dimension of said root being taken at a point on said neck portion adjacent said surface of said shaft, said transition portion between said knob and said neck being disposed so as to prevent stress concentration adjacent said root as said root radially secures said blade to said rotor.

Claim 10

The rotor of claim 7, wherein said rooted blades are attached to said shaft by said root portions thereof at a first point of fixity therebetween, and, said rootless blade is attached to said shaft by said rooted blades at a second point of fixity, said first point of fixity being radially inward on said shaft from said second point of fixity, said difference in points of fixity for said rooted blades on said rootless blade permitting relative motion to occur between said rooted blades and said rootless blade, said rotor further comprising means for axially securing said rootless blades to said shaft, sAid means comprising a pin member radially extending form said underside surface of said rootless blade, and a slot disposed circumferentially about said shaft surface, said direct abutment of said underside surface of said platform of said rootless blade against said surface of said shaft permitting said pin member to be radially inserted and radially engage said slot to axially secure said rootless blade to said shaft.