Unducted rectifier for a turbomachine, turbomachine module and aircraft turbomachine
An unducted rectifier for a turbomachine is provided. The rectifier includes: (1) stator vanes each having a root and a blade radially projecting from the root, the root having two half-platforms; (2) pivots, each associated with a vane mounted so as to pivot about a pitch axis and configured to connect to a system for changing the pitch of the blades, each pivot having an upper platform and a cylindrical lower portion; and (3) attachment systems for attaching the half-platforms of the root of the vane to the associated pivot, each having two plates having a substantially identical shape to each half-platform and a clamping system for clamping the half-platforms between the plates of the attachment system and the upper platform of the pivot.
1. An unducted flow straightener for a turbomachine having a longitudinal axis, the flow straightener comprising:
a plurality of stator vanes extending along a radial axis, each stator vane comprising a root and a blade rising radially from the root, the root having two half-platforms extending on either side of the blade;
a plurality of pivots, each associated with a stator vane and pivotally mounted along a pitch axis and configured to connect to a pitch change system for changing the pitch of the blades, each pivot having an upper platform and a cylindrical lower portion; and
a plurality of attachment systems, each associated with a stator vane and being adapted to attach the half-platforms of the root of the vane to the associated pivot, each attachment system comprising a clamping system and two plates arranged on either side of the blade, each of the plates having a shape identical to each half-platform, the clamping system being designed to clamp the half-platforms of the root of the vane between the plates of the attachment system and the upper platform of the pivot,
wherein each half-platform of a root of a vane has at least two through-orifices, each upper platform of a pivot associated with the root of the vane has through-holes each arranged opposite a through-orifice of a half-platform, and each plate of an attachment system associated with a root of the vane has through holes each arranged opposite a through orifice of a half-platform,
wherein the clamping system comprises screws and rotation-stop means arranged to clamp the half-platforms of the root of the vane between the plates of the attachment system and the upper platform of the pivot, each screw being inserted successively into a through hole in a plate of the attachment system, an orifice in a half-platform, a through hole in the pivot, and the rotation-stop means,
wherein each lower portion of a pivot comprises a body and a segment of larger diameter than the body arranged between the body and the upper platform, and
wherein each rotation-stop means of a clamping system comprises a flattened area coming in abutment against the segment of larger diameter.
2. The flow straightener of claim 1 , wherein, for each assembly formed by a stator vane, an associated pivot, and an associated attachment system:
each half-platform is connected to the blade of the vane by a connection fillet;
each upper platform of the pivot is circular in shape; and
each lower portion of the pivot has a diameter smaller than that of the upper platform,
and wherein each plate of the attachment system is a half-moon-shaped, comprising a lateral edge shaped to match the connection fillet of the half-platform against which the plate is clamped.
3. The flow straightener of claim 2 , wherein each lateral edge of a plate of an attachment system has a gasket arranged along the entire length of the lateral edge and shaped to match the connection fillet of the half-platform against which the plate is clamped.
4. The flow straightener of claim 2 , wherein each half-platform is flat and/or is half-disc-shaped.
5. The flow straightener of claim 1 , wherein
the clamping system comprises at least four screws and four rotation-stop means arranged to clamp the half-platforms of the root of the vane between the plates of the attachment system and the upper platform of the pivot, each screw being inserted successively into a through hole in a plate of the attachment system, an orifice in a half-platform, a through hole in the pivot, and the rotation-stop means.
6. The flow straightener of claim 1 , wherein each rotation-stop means is a nut crimped to prevent its rotation.
7. The flow straightener of claim 1 , wherein each rotation-stop means of a clamping system is a nut trapped in a through hole of an upper platform of a pivot.
8. The flow straightener of claim 1 , wherein each through-orifice of a half-platform has a metallic insert.
9. The flow straightener of claim 1 , wherein each half-platform of a root of a vane has two dampers arranged on two opposite faces of the half-platform, one of the dampers being arranged between the half-platform and a plate and the other of the dampers being arranged between the half-platform and the upper platform of the pivot.
10. The flow straightener of claim 1 , wherein the vanes are made of a composite material with a fiber-reinforced polymer matrix, and the two half-platforms of the root of the vane are produced by an unbinding in the weaving of the fibers of the vanes.
11. A turbomachine module with a longitudinal axis, the turbomachine module comprising:
an unducted propeller designed to be driven in rotation about the longitudinal axis;
at least one unducted flow straightener according to claim 1 ; and
a pitch change system for changing the pitch of the blades of the stator vanes about a pitch axis.
12. An aircraft turbomachine comprising at least one turbomachine module according to claim 11 .
13. The flow straightener of claim 1 , wherein the upper platform of each pivot is shaped like a disc.