# US 11,993,408 B2 · Masking bladed disc for reducing the radar signature of a moving compressor moving disc of a jet engine

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- Number: US 11,993,408 B2
- Document ID: US11993408B2
- Status: Granted
- Kind: B2
- Application number: 17/415,395
- Filed: 2019-12-04
- Published: 2022-02-10
- Granted: 2024-05-28
- Earliest claimed: 2018-12-20
- Assignees: Safran Aircraft Engines
- Applicants: Safran Aircraft Engines
- Inventors: Michel Dumas; Laurent Christophe Francis Villaines
- Web page: https://patentgrep.com/patent/US11993408B2

## CPC

- B64U 20/10: for stealth, e.g. reduction of cross-section detectable by radars
- F04D 29/563: {specially adapted for elastic fluid pumps}
- B64D 7/00: Arrangement of military equipment, e.g. armaments, armament accessories or military shielding, in aircraft; Adaptations of armament mountings for aircraft (dropping bombs or the like B64D1/00)
- F01D 5/141: {Shape, i.e. outer, aerodynamic form (F01D5/148 - F01D5/20 take precedence; blade construction F01D5/147)}
- F01D 9/02: Nozzles; Nozzle boxes; Stator blades; Guide conduits {, e.g. individual nozzles (nozzle boxes F01D9/047)}
- F01D 9/041: {using blades (F01D5/148 takes precedence)}
- F01D 17/162: {for axial flow, i.e. the vanes turning around axes which are essentially perpendicular to the rotor centre line (F01D17/167 takes precedence)}
- F02C 3/04: having a turbine driving a compressor (power transmission arrangements F02C7/36; control of working fluid flow F02C9/16)
- F02C 7/042: having variable geometry
- F02K 3/06: with front fan
- F04D 19/002: {Axial flow fans}
- F04D 29/181: {Axial flow rotors (F04D29/185 take precedence)}
- F04D 29/544: {Blade shapes}
- F05D 2220/3217: for the first stage of a compressor or a low pressure compressor
- F05D 2220/323: for aircraft propulsion, e.g. jet engines
- F05D 2240/12: Fluid guiding means, e.g. vanes
- F05D 2250/711: convex
- F05D 2250/712: concave
- F05D 2250/75: given by its similarity to a letter, e.g. T-shaped
- F05D 2250/90: Variable geometry
- F05D 2260/96: Preventing, counteracting or reducing vibration or noise
- Y02T 50/60: Efficient propulsion technologies, e.g. for aircraft
- B64U: UNMANNED AERIAL VEHICLES [UAV]; EQUIPMENT THEREFOR
- F04D: NON-POSITIVE-DISPLACEMENT PUMPS (engine fuel-injection pumps F02M; ion pumps H01J41/12; electrodynamic pumps H02K44/02)
- B64D: EQUIPMENT FOR FITTING IN OR TO AIRCRAFT; FLIGHT SUITS; PARACHUTES; ARRANGEMENT OR MOUNTING OF POWER PLANTS OR PROPULSION TRANSMISSIONS IN AIRCRAFT
- F01D: NON-POSITIVE DISPLACEMENT MACHINES OR ENGINES, e.g. STEAM TURBINES (machines or engines for liquids F03; non-positive displacement pumps F04D)
- F02C: GAS-TURBINE PLANTS; AIR INTAKES FOR JET-PROPULSION PLANTS; CONTROLLING FUEL SUPPLY IN AIR-BREATHING JET-PROPULSION PLANTS (construction of turbines F01D; jet-propulsion plants F02K; construction of compressors or fans F04; generating combustion products of high pressure or high velocity F23R; using gas turbines in compression refrigeration plants F25B11/00)
- F02K: JET-PROPULSION PLANTS (features of jet-propulsion plants common to gas-turbine plants, air intakes or fuel supply control of air-breathing jet-propulsion plants F02C7/00, F02C9/00)
- F05D: INDEXING SCHEME FOR ASPECTS RELATING TO NON-POSITIVE-DISPLACEMENT MACHINES OR ENGINES, GAS-TURBINES OR JET-PROPULSION PLANTS
- Y02T: CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION

## Abstract

A bladed disc for masking a moving disc of a jet engine, including blades, each blade including a pressure-side wall and a suction-side wall that meet at a leading-edge and at a trailing edge, and wherein each blade has a pressure-side wall and a suction-side wall each including a concave zone and a convex zone that are at a distance from the leading-edge and from the trailing edge and are spaced apart from one another, these concave zones and these convex zones each extending over the majority of the height of the blade, the concave zone of the pressure-side wall is opposite the convex zone of the suction-side wall, the concave zone of the suction-side wall is opposite the convex zone of the pressure-side wall.

## Claims

### Claim 1

A bladed wheel for masking a moving wheel of a turbojet engine, comprising:
vanes, each vane including a lower surface wall and an upper surface wall joined at a leading edge and at a trailing edge and extending along a span axis from a root to a tip, wherein:
the lower surface wall includes an upstream axial portion extending from the leading edge to a convex zone of said lower surface wall, a central portion extending from the convex zone to a concave zone of said lower surface wall, and a downstream axial portion extending from the concave zone to the trailing edge, the upstream axial portion and the downstream axial portion extending along an extension direction, and the central portion being tilted relative to the extension direction and having an inversion of curvature;
the upper surface wall includes an upstream axial portion extending from the leading edge to a concave zone of said upper surface wall, a central portion extending from the concave zone to a convex zone of said upper surface wall, and a downstream axial portion extending from the convex zone to the trailing edge, the upstream axial portion and the downstream axial portion extending along the extension direction, and the central portion being tilted relative to the extension direction and having an inversion of curvature;
said concave zones and said convex zones each extend over most of the height of the vane along its span axis;
the concave zone of the lower surface wall faces the convex zone of the upper surface wall, and the concave zone of the upper surface wall faces the convex zone of the lower surface wall;
each vane is a variable setting vane mounted to pivot about a radial axis coinciding with its leading edge;
in one position of the variable setting vane, the extension direction is parallel to a longitudinal axis of the turbojet engine;
two consecutive vanes delimit therebetween an inter-vane fluid passage channel being a baffle between central portions of the two consecutive vanes tilted at a tilt angle with respect to the longitudinal axis of the turbojet engine, the inter-vane fluid passage channel presenting a pitch which is a distance separating the two consecutive vanes in a top view along a circumference of the bladed wheel; and
a relative pitch of the inter-vane fluid passage channel corresponding to a ratio of the pitch to a chord length of the central portion of the vanes is less than 0.6, and the tilt angle is less than 30°.

### Claim 2 (depends on 1)

The bladed wheel according to claim 1, wherein each vane comprises a downstream portion extending from the trailing edge to the convex and concave zones of its upper surface wall and lower surface wall respectively, and wherein each downstream portion is a variable setting flap pivotably mounted between the convex and concave zones of its upper surface wall and lower surface wall respectively.

### Claim 3 (depends on 1)

The bladed wheel according to claim 1, wherein the vanes are covered with a coating absorbing electromagnetic radiations.

### Claim 4 (depends on 1)

A turbojet engine comprising a low pressure compressor including a moving wheel upstream of which an inlet steering wheel is arranged, upstream of which a masking bladed wheel according to claim 1 is mounted.

### Claim 5 (depends on 1)

A turbojet engine comprising a low pressure compressor including a moving wheel upstream of which a masking bladed wheel according to claim 1 is arranged.

### Claim 6 (depends on 4)

The turbojet engine according to claim 4, further comprising a bent inlet duct connected to the turbojet engine and supplying the turbojet engine with air.

### Claim 7 (depends on 5)

The turbojet engine according to claim 5, further comprising a bent inlet duct connected to the turbojet engine and supplying the turbojet engine with air.

### Claim 8

A bladed wheel for masking a moving wheel of a turbojet engine, comprising:
vanes, each vane including a lower surface wall and an upper surface wall joined at a leading edge and at a trailing edge and extending along a span axis from a root to a tip, wherein:
the lower surface wall includes an upstream axial portion extending from the leading edge to a convex zone of said lower surface wall, a central portion extending from the convex zone to a concave zone of said lower surface wall, and a downstream axial portion extending from the concave zone to the trailing edge, the upstream axial portion and the downstream axial portion extending along an extension direction, and the central portion being tilted relative to the extension direction and having an inversion of curvature;
the upper surface wall includes an upstream axial portion extending from the leading edge to a concave zone of said upper surface wall, a central portion extending from the concave zone to a convex zone of said upper surface wall, and a downstream axial portion extending from the convex zone to the trailing edge, the upstream axial portion and the downstream axial portion extending along the extension direction, and the central portion being tilted relative to the extension direction and having an inversion of curvature;
said concave zones and said convex zones each extend over most of the height of the vane along its span axis;
the concave zone of the lower surface wall faces the convex zone of the upper surface wall, and the concave zone of the upper surface wall faces the convex zone of the lower surface wall;
each vane is a variable setting vane mounted to pivot about a radial axis coinciding with its leading edge;
the upstream axial portion and the downstream axial portion of the lower surface wall extend constantly parallel to each other, and the upstream axial portion and the downstream axial portion of the upper surface wall extend constantly parallel to each other;
two consecutive vanes delimit therebetween an inter-vane fluid passage channel being a baffle between central portions of the two consecutive vanes tilted at a tilt angle with respect to a longitudinal axis of the turbojet engine, the inter-vane fluid passage channel presenting a pitch which is a distance separating the two consecutive vanes in a top view along a circumference of the bladed wheel; and
a relative pitch of the inter-vane fluid passage channel corresponding to a ratio of the pitch to a chord length of the central portion of the vanes is less than 0.6, and the tilt angle is less than 30°.