Turbomachine having an unducted fan provided with air guide means
View Patent ↗A turbomachine having two unducted external fans mounted to contrarotate about a common axis, the fans constituting respectively an upstream fan and a downstream fan, is disclosed. At least some of the blades of the upstream fan carry an air guide device on their radially outer end portions, the air guide device being outwardly oriented on going from upstream to downstream and serving to deflect the vortices that are formed in the vicinity of the blade tips of the upstream fan radially to outside the blades of the downstream fan.
1. A turbomachine comprising:
two unducted external fans mounted to contrarotate about a common axis, the fans constituting respectively an upstream fan and a downstream fan,
wherein at least some of the blades of the upstream fan carry air guide means on radially outer end portions thereof, the air guide means being outwardly oriented on going from upstream to downstream and serving to deflect vortices that are formed in the vicinity of blade tips of the upstream fan radially to outside the blades of the downstream fan,
wherein the air guide means of the blade includes at least one fin projecting from a suction side of the blade and/or at least one fin projecting from a pressure side of the blade, and
wherein an axial length of each fin is less than an axial length of the blade and each fin is rectilinear.
2. A turbomachine according to claim 1 , wherein each fin is formed integrally with the blade or is a fitting fastened thereto.
3. A turbomachine according to claim 1 , wherein each fin has an axial dimension or length lying in the range about 20% to about 90% of the axial dimension or length of the blade.
4. A turbomachine according to claim 1 , wherein each fin has a thickness or height that is approximately equal to the thickness of the boundary layer of the flow of air over the blade.
5. A turbomachine according to claim 1 , wherein the blade carries a plurality of fins on at least one of its faces, the fins being substantially parallel to one another.
6. A turbomachine according to claim 5 , wherein the fins are located close to the leading edge and/or the trailing edge of the blade.
7. A turbomachine according to claim 5 , wherein the fins are distributed over a zone occupying about 50% to about 95% of the radial dimension of the blade as measured from the root of the blade, and are of varying length that increases progressively with increasing distance of the fins from the axis of rotation.
8. An external fan blade for a turbomachine according to claim 1 , wherein, at its outer end, the fan blade includes air guide means which are formed by at least one or two parallel fins projecting from at least one of its faces and extending outwards on going from upstream to downstream.
9. A turbomachine comprising:
two unducted external fans mounted to contratotate about a common axis, the fans constituting respectively an upstream fan and downstream fan,
wherein at least some of the blades of the upstream fan carry air guide means on radially outer end portions thereof, the air guide means being outwardly oriented on going from upstream to downstream and serving to deflect vortices that are formed in the vicinity of blade tips of the upstream fan radially to outside the blades of the downstream fan,
wherein the air guide means of the blade includes at least one fin projecting from a suction side of the blade and/or at least one fin projecting from a pressure side of the blade, and
wherein an axial length of each fin is less than an axial length of the blade and each fin includes a rectilinear upstream portion parallel to an axis of the turbomachine and a curved downstream portion with a concave side facing outwards.