Aircraft turboprop engine comprising two coaxial propellers

Patent metadata

Field	Value
Publication number	US-2016159459-A1
Application number	US-201514723990-A
Country	US
Kind code	A1
Filing date	May 28, 2015
Priority date	May 28, 2014
Publication date	Jun 9, 2016
Grant date	—

Abstract

The invention relates to an aircraft turboprop engine comprising two unducted propellers, coaxial about a rotation axis (LL), respectively upstream ( 12 ) and downstream ( 14′ ), each propeller comprising an annular row of blades, the blades of the downstream propeller ( 14′ ) each having a truncated head and each comprising a leading edge ( 20′ ) and a trailing edge ( 22′ ), the radially external ends (A 2, B 1 ) of which are distant from each other and are connected by a terminal edge ( 21′ ), characterised in that the terminal edge ( 21′ ) of each blade of the downstream propeller ( 14′ ) has, at at least two points, tangents in a meridian plane having different slopes, the upstream end (A) of the terminal edge defining a maximum radial dimension (R 2 ) of the blade and its downstream end (B 1 ) defining a minimum radial dimension (R 3 ) of said terminal edge.

First claim

1 . Aircraft turboprop engine comprising two unducted propellers, coaxial about a rotation axis, respectively upstream and downstream, each propeller comprising an annular row of blades, the blades of the downstream propeller each having a truncated head and each comprising a leading edge and a trailing edge, the radially external ends of which are distant from each other and are connected by a terminal edge, in which the terminal edge of each blade of the downstream propeller has, at at least two points, tangents in a meridian plane having different slopes, the upstream end of the terminal edge defining a maximum radial dimension of the blade and its downstream end defining a minimum radial dimension of said terminal edge, characterised in that each blade of the downstream propeller is situated inside a cone converging towards the downstream end, which meets the terminal edges of the blades of the upstream propeller and the radial dimension of which in the transverse plane passing through the downstream end of the terminal edge is less than the maximum radial dimension of said blade of the downstream propeller.

2 . Turboprop engine according to claim 1 , characterised in that the radial distance from the terminal edge to the rotation axis is a concave function of the position along the rotation axis.

3 . Turboprop engine according to claim 2 , characterised in that the terminal edge comprises a substantially rectilinear upstream part defining the maximum radial dimension of the blade.

4 . Turboprop engine according to claim 1 , characterised in that the terminal edge comprises a downstream part inclined from upstream to downstream radially towards the inside, the axial extension of this downstream part being at least equal to 10% of the axial extension of the reference chord of the blade at the downstream end of the terminal edge.

5 . Turboprop engine according to claim 4 , characterised in that the radial extension of the terminal edge is no more than 20% of the maximum radial dimension of the blade.

6 . Turboprop engine according to claim 4 , characterised in that the downstream part of the terminal edge comprises at least one portion with a rounded shape and the centres of curvature of which are arranged so that the terminal part curves more and more towards the rotation axis going towards the downstream end of the terminal edge.

7 . Turboprop engine according to claim 6 , characterised in that the downstream part of the terminal edge comprises a plurality of successive portions with a rounded shape and the centres of curvature of which are arranged so that the terminal part curves more and more towards the rotation axis going towards the downstream end of the terminal edge.

8 . Turboprop engine according to claim 6 , characterised in that the portion or portions have radii of curvature that decrease going from upstream to downstream.

9 . Turboprop engine according to claim 1 , in which the trailing edge of the blades of the downstream propeller extend, at least close to its radial end, from upstream to downstream radially towards the outside.

10 . Turboprop engine according to claim 1 , in which the leading edge of the blades of the downstream propeller extend, at least close to its radial end, from upstream to downstream radially towards the outside.

11 . Method for producing a downstream propeller of an aircraft turboprop engine according to claim 1 , characterised in that it comprises:
a step consisting in designing blades for a reference downstream propeller, each blade having a truncated head and comprising a leading edge and a trailing edge, the radially external ends of which are distant from each other and are connected by a substantially rectilinear terminal edge, having a radial dimension substantially equal to the maximum radial dimension of the blades of the downstream propeller to be produced; a step of trimming the downstream and radially external end of each of said blades for a reference downstream propeller.

Assignees

• Snecma

Inventors

• Louet Anthony Pascal Eloi
• Dejeu Clement Marcel Maurice
• Vlastuin Jonathan Evert

Classifications

• F01D5/141 Primary

  Shape, i.e. outer, aerodynamic form (F01D5/148 - F01D5/20 take precedence; blade construction F01D5/147) · CPC title

• F05D2230/10

  by removing material · CPC title

• B64C11/18 Primary

  Aerodynamic features · CPC title

• F02K3/072

  with counter-rotating {, e.g. fan} rotors · CPC title

• F01D1/26

  traversed by the working-fluid substantially axially · CPC title