# US 2021/0277828 A1 · Alternating helicoid cell structure and methods of producing the same > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2021/0277828 A1 - Document ID: US20210277828A1 - Status: Published application - Kind: A1 - Application number: 16/812,781 - Filed: 2020-03-09 - Published: 2021-09-09 - Earliest claimed: 2020-03-09 - Assignees: Honeywell International Inc. - Applicants: Honeywell International Inc. - Inventors: Shawn Alstad; William B. Schuster - Web page: https://patentgrep.com/patent/US20210277828A1 ## CPC - F02C 7/24: Heat or noise insulation (air intakes having provisions for noise suppression F02C7/045; turbine exhaust heads, chambers, or the like F01D25/30; silencing nozzles of jet-propulsion plants F02K1/00) - G10K 11/172: using resonance effects - E04B 1/84: Sound-absorbing elements - G10K 11/16: Methods or devices for protecting against, or for damping, noise or other acoustic waves in general (G10K11/36 takes precedence) - E04B 2001/8428: {containing specially shaped acoustical bodies, e.g. funnels, egg-crates, fanfolds} - E04B 2001/8485: {the opening being restricted, e.g. forming Helmoltz resonators} - F05D 2250/25: helical - 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) - G10K: SOUND-PRODUCING DEVICES; METHODS OR DEVICES FOR PROTECTING AGAINST, OR FOR DAMPING, NOISE OR OTHER ACOUSTIC WAVES IN GENERAL; ACOUSTICS NOT OTHERWISE PROVIDED FOR - E04B: GENERAL BUILDING CONSTRUCTIONS; WALLS, e.g. PARTITIONS; ROOFS; FLOORS; CEILINGS; INSULATION OR OTHER PROTECTION OF BUILDINGS (border constructions of opening in walls, floors or ceilings E06B1/00; {electromagnetic shielding H05K9/0001}) - F05D: INDEXING SCHEME FOR ASPECTS RELATING TO NON-POSITIVE-DISPLACEMENT MACHINES OR ENGINES, GAS-TURBINES OR JET-PROPULSION PLANTS ## Abstract An alternating clockwise and counterclockwise helicoid cell structure for use in acoustic panels. The cell structure geometry may be easily replicated and tiled using additive manufacturing. The cell structure has at least an outer cavity and an inner cavity. The cavities are coaxial, share the same height, same entrance side, and same cell structure floor. The inner cavity includes a number of equal-volume inner chambers rotated uniformly in a first direction around the shared central axis; and the outer cavity includes a second number of equal-volume outer chambers rotated uniformly in an opposite direction to the first direction around the shared central axis. In various embodiments, one or more perforated baffles may extend, internally, across a chamber, perpendicular to direction of sound waves at the location of the perforated baffle. In various embodiments, one or more port openings from the outer cavity to the inner cavity may be present. ## Claims ### Claim 1 A cell structure for use in an acoustic panel, the cell structure comprising: a first cavity having a regular shape cross section perpendicular to a central axis, the first cavity having a continuous first boundary wall, the first cavity having a floor side, a cell height, and an entrance side defined by a first incircle, the floor side covered by a cell structure floor; a second cavity disposed coaxially within the first cavity, the second cavity having the regular shape cross section perpendicular to the central axis, the second cavity having a continuous second boundary wall, the second cavity having a floor side covered by the cell structure floor, the cell height, and an entrance side defined by a second incircle; a first number of inner chambers disposed within the second cavity from the second cavity entrance side to the cell structure floor, each of the inner chambers having an equal inner chamber cross sectional area created by radially dividing the second incircle, the inner chambers being rotated in a first direction around the central axis by at least p rotations per inch from the second cavity entrance side to the cell structure floor; and a second number of outer chambers disposed in a volume between the continuous first boundary wall and the continuous second boundary wall, from the first cavity entrance side to the cell structure floor, each of the outer chambers having an equal outer chamber cross sectional area created by radially dividing the first incircle into equally sized outer sections, the outer chambers being rotated around the central axis in an opposing direction to the first direction by the at least p rotations per inch from the first cavity entrance side to the cell structure floor; a partition dividing an outer chamber into two modified outer chambers; and a port opening from the divided outer chamber into the inner cavity, the port opening positioned near the partition. ### Claim 2 (depends on 1) The cell structure of claim 1, wherein a size of the port opening is a function of the first percentage of the outer chamber cross sectional area. ### Claim 3 (depends on 2) The cell structure of claim 2, wherein a shape of the port openings is triangular. ### Claim 4 (depends on 3) The cell structure of claim 3, wherein a location of the port openings is in close proximity to a location of the partition. ### Claim 5 (depends on 4) The cell structure of claim 4, further comprising a perforated lid that extends completely across the entrance side. ### Claim 6 (depends on 4) The cell structure of claim 4, wherein the first number is 6 and the second number is 6. ### Claim 7 (depends on 4) The cell structure of claim 4, wherein the second number is twice the first number. ### Claim 8 (depends on 4) The cell structure of claim 4, wherein the first percentage is between 5 and 30 percent. ### Claim 9 (depends on 4) The cell structure of claim 4, wherein the size of the port opening is equal to the first percentage of the outer chamber cross sectional area. ### Claim 10 A cell structure for use in an acoustic panel, the cell structure comprising: a continuous first boundary wall having a cell height measured between a floor side and an entrance side, the continuous first boundary wall having a central axis and defining a first cavity with a regular shape cross section perpendicular to the central axis; a continuous second boundary wall disposed coaxially within the first cavity and defining a second cavity, the second cavity having the regular shape cross section perpendicular to the central axis, the second cavity having a floor side covered by the cell structure floor, the cell height, and an entrance side defined by a second incircle; a first number of inner chambers disposed within the second cavity from the second cavity entrance side to the cell structure floor, each of the inner chambers having an equal inner chamber cross sectional area created by radially dividing the second incircle, the inner chambers being rotated in a first direction around the central axis by at least p rotations per inch from the second cavity entrance side to the cell structure floor; and a second number of outer chambers disposed in a volume between the continuous first boundary wall and the continuous second boundary wall, from the first cavity entrance side to the cell structure floor, each of the outer chambers having an equal outer chamber cross sectional area created by radially dividing the first incircle into equally sized outer sections, the outer chambers being rotated around the central axis in an opposing direction to the first direction by the at least p rotations per inch from the first cavity entrance side to the cell structure floor. ### Claim 11 (depends on 10) The cell structure of claim 10, further including: a partition disposed within in an outer chamber and completely occluding the outer chamber at the location of the partition; and a port opening positioned near the partition, the port opening located on the continuous second boundry wall of the outer chamber, providing throughput into the inner cavity. ### Claim 12 (depends on 11) The cell structure of claim 11, further including a perforated baffle disposed within the outer chamber, the perforated baffle extending across the outer chamber cross sectional area and having perforations that open up a first percentage of the outer chamber cross sectional area to throughflow. ### Claim 13 (depends on 12) The cell structure of claim 12, wherein a shape of the port opening is triangular. ### Claim 14 (depends on 12) The cell structure of claim 12, wherein a location of the port opening with respect to a location of the partition is a function of a cross sectional area of the outer chamber. ### Claim 15 (depends on 12) The cell structure of claim 12, wherein a size of the port opening is equal to the first percentage of the outer chamber cross sectional area. ### Claim 16 (depends on 12) The cell structure of claim 12, wherein there are two times as many outer chambers as inner chambers. ### Claim 17 (depends on 12) The cell structure of claim 12, wherein the first number is 6 and the second number is 6. ### Claim 18 (depends on 12) The cell structure of claim 12, wherein the first percentage is between 5 and 30 percent. ### Claim 19 An acoustic panel comprising: an array of a plurality of helicoid cell structures, each helicoid cell structure comprising: a continuous first boundary wall having a cell height measured between a floor side and an entrance side, the continuous first boundary wall having a central axis and defining a first cavity with a regular shape cross section perpendicular to the central axis; a continuous second boundary wall disposed coaxially within the first cavity and defining a second cavity, the second cavity having the regular shape cross section perpendicular to the central axis, the second cavity having a floor side covered by the cell structure floor, the cell height, and an entrance side defined by a second incircle; a first number of inner chambers disposed within the second cavity from the second cavity entrance side to the cell structure floor, each of the inner chambers having an equal inner chamber cross sectional area created by radially dividing the second incircle, the inner chambers being rotated in a first direction around the central axis by at least p rotations per inch from the second cavity entrance side to the cell structure floor; a second number of outer chambers disposed in a volume between the continuous first boundary wall and the continuous second boundary wall, from the first cavity entrance side to the cell structure floor, each of the outer chambers having an equal outer chamber cross sectional area created by radially dividing the first incircle into equally sized outer sections, the outer chambers being rotated around the central axis in an opposing direction to the first direction by the at least p rotations per inch from the first cavity entrance side to the cell structure floor; and a continuous surface layer comprising, for each of the plurality of helicoid cell structures, a respective perforated lid. ### Claim 20 (depends on 19) The acoustic panel of claim 19, wherein the array of helicoid cell structures has been generated using additive manufacturing.