# US 11,898,468 B2 · Sub-assembly for a low-pressure compressor of an aircraft turbine engine > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 11,898,468 B2 - Document ID: US11898468B2 - Status: Granted - Kind: B2 - Application number: 17/999,261 - Filed: 2021-05-11 - Published: 2023-06-15 - Granted: 2024-02-13 - Earliest claimed: 2020-05-20 - Assignees: Safran Aero Boosters SA - Applicants: Safran Aero Boosters - Inventors: Stéphane Hiernaux - Web page: https://patentgrep.com/patent/US11898468B2 ## CPC - F01D 9/041: {using blades (F01D5/148 takes precedence)} - F04D 29/685: {Inducing localised fluid recirculation in the stator-rotor interface} - F04D 29/321: {for axial flow compressors} - F04D 29/665: {by means of resonance chambers or interference} - 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 - Y02T 50/60: Efficient propulsion technologies, e.g. for aircraft - F01D: NON-POSITIVE DISPLACEMENT MACHINES OR ENGINES, e.g. STEAM TURBINES (machines or engines for liquids F03; non-positive displacement pumps F04D) - F04D: NON-POSITIVE-DISPLACEMENT PUMPS (engine fuel-injection pumps F02M; ion pumps H01J41/12; electrodynamic pumps H02K44/02) - 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 sub-assembly for a low-pressure compressor of an aircraft turbine engine includes a straightener provided with cantilevered vanes and a rotor hub having a cavity covered by an inner shroud opposite the vanes. Orifices are made in the inner shroud to allow an air flow to circulate in the downstream to upstream direction of the low-pressure compressor. ## Claims ### Claim 1 A sub-assembly for a low-pressure compressor of an aircraft turbine engine extending along an engine axis directed from upstream towards downstream, the sub-assembly comprising: a rotor comprising a hub extending axially and circumferentially around the engine axis; and a stator comprising a straightener equipped with vanes extending substantially radially towards the hub; wherein: the hub comprises an inner recess directed towards the engine axis; and the rotor comprises an inner shroud: covering the inner recess so as to define a cavity between the hub and the inner shroud, each of the vanes comprising a free head facing at least partially the inner shroud and/or the cavity; comprising orifices in fluidic communication with the cavity; and wherein the cavity is partitioned into cells bounded by edges, each cell extending both axially and circumferentially, in an axially inclined direction, so that each cell comprises: a downstream segment radially facing a space between first and second of the vanes which are successively circumferentially aligned; and an upstream segment radially facing another space between third and fourth of the vanes which are successively circumferentially aligned, at least one of the third and the fourth vanes being distinct from both the first and second vanes, the fourth vane corresponding to the first vane, so that the third, first and second vanes, in that order, are successively aligned circumferentially: wherein the inner recess is formed by at least one deformation of a wall of the hub, and the inner shroud is formed of an annular plate portion. ### Claim 2 (depends on 1) The sub-assembly according to claim 1, wherein a first of the orifices extends at least downstream of a leading edge of one of the vanes, and a second of the orifices extends at least upstream of said leading edge. ### Claim 3 (depends on 2) The sub-assembly according to claim 2, wherein at least one segment of the first orifice extends axially between respective radial projections on the inner shroud and/or the hub of the leading edge and a trailing edge of said vane, the segment of the first orifice and the second orifice being at least partially axially aligned. ### Claim 4 (depends on 2) The sub-assembly according to claim 2, wherein the inner shroud comprises a plurality of pairs of the first and second orifices. ### Claim 5 (depends on 1) The sub-assembly according to claim 1, wherein a collection of said orifices are circumferentially aligned and each have a parallelogram-shaped profile extending axially with an angle of inclination (α) of at most 60° with respect to the engine axis. ### Claim 6 (depends on 5) The sub-assembly according to claim 5, wherein each of the orifices of the collection extends upstream and downstream of a leading edge of each vane. ### Claim 7 (depends on 6) The sub-assembly according to claim 6, wherein each of the orifices of the collection comprises: an upstream end, located upstream of said leading edge, at an axial distance (A) therefrom of at most 25% of a chord of each vane; and a downstream end, located downstream of said leading edge, at an axial distance (A′) therefrom of at most 75% of the chord of each vane. ### Claim 8 (depends on 5) The sub-assembly according to claim 5, wherein an axial length (C) of each orifice of the collection is between 10 and 75% of a chord of each vane. ### Claim 9 (depends on 8) The sub-assembly according to claim 8 wherein the orifices comprise two circumferentially aligned groups of orifices, the groups being at an axial distance (D) from each other of between 10 and 50% of a chord of each vane, and one of the groups corresponds to the collection and in that the orifices of the other of the groups each have a further parallelogram-shaped profile. ### Claim 10 (depends on 1) The sub-assembly according to claim 1, wherein the orifices comprise two circumferentially aligned groups of orifices, the groups being at an axial distance (D) from each other of between 10 and 50% of a chord of each vane. ### Claim 11 (depends on 1) The sub-assembly according to claim 1, wherein edges of the orifices are bevelled, so as to have a flared profile. ### Claim 12 (depends on 1) A low-pressure compressor for an aircraft turbine engine, comprising a sub-assembly according to claim 1. ### Claim 13 (depends on 12) An aircraft turbine engine equipped with a low-pressure compressor according to claim 12. ### Claim 14 (depends on 1) The sub-assembly according to claim 1, wherein the inner shroud is formed from a sheet-metal portion. ### Claim 15 (depends on 1) The sub-assembly according to claim 1, wherein the inner shroud has a constant thickness.