# US 2018/0023409 A1 · Turbine shroud with abradable layer having ridges with holes > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2018/0023409 A1 - Document ID: US20180023409A1 - Status: Published application - Kind: A1 - Application number: 15/548,481 - Filed: 2015-12-09 - Published: 2018-01-25 - Earliest claimed: 2015-02-18 - Assignees: Siemens Aktiengesellschaft - Applicants: Siemens Aktiengesellschaft - Inventors: Ching-Pang Lee; Ramesh Subramanian; Kok-Mun Tham - Web page: https://patentgrep.com/patent/US20180023409A1 ## CPC - F01D 11/122: {with erodable or abradable material (blades having cutting or grinding tips F01D5/20)} - F01D 9/04: forming ring or sector - F05D 2220/32: in gas turbines - F05D 2240/11: Shroud seal segments - F05D 2240/305: related to the pressure side of a rotor blade - F05D 2250/181: ridged - F05D 2250/60: Structure; Surface texture - F01D: NON-POSITIVE DISPLACEMENT MACHINES OR ENGINES, e.g. STEAM TURBINES (machines or engines for liquids F03; non-positive displacement pumps F04D) - F05D: INDEXING SCHEME FOR ASPECTS RELATING TO NON-POSITIVE-DISPLACEMENT MACHINES OR ENGINES, GAS-TURBINES OR JET-PROPULSION PLANTS ## Abstract Turbine and compressor casing abradable component embodiments for turbine engines vary localized porosity or abradability through use of holes or dimple depressions of desired polygonal profiles that are formed into the surface of otherwise monolithic abradable surfaces or rib structures. Abradable porosity within a rib is varied locally by changing any one or more of hole/depression depth, diameter, array pitch density, and/or volume. In various embodiments, localized porosity increases and corresponding abradability increases axially from the upstream or forward axial end of the abradable surface to the downstream or aft end of the surface. In this way, the forward axial end of the abradable surface has less porosity to counter hot working gas erosion of the surface, while the more aft portions of the abradable surface accommodate blade cutting and incursion with lower likelihood of blade tip wear. ## Claims ### Claim 1 A turbine engine ring segment component, adapted for coupling to an interior circumference of a turbine casing in opposed orientation with a rotating turbine blade tip circumferential swept path, the blade tip having a rotational direction, a leading edge, a mid-chord cutoff point on its pressure side concave surface and a trailing edge, the component comprising: a curved support surface adapted for coupling to a turbine casing inner circumference, the support surface having upstream and downstream axial ends and a support surface curvature radius defined by a support surface central axis; an abradable substrate coupled to the support surface, having a substrate surface with a plan form pattern of grooves and vertically projecting ridges facing the support surface central axis, the grooves and ridges originating and terminating axially between the support surface ends and defining forward and aft segment portions; each forward segment portion originating nearer the support surface upstream end; each aft segment portion originating at the adjoining forward segment termination and terminating nearer the support surface downstream end; a pattern of indentations respectively having cross sectional profiles and depth, formed in the ridges, for selectively varying porosity and/or abradability of the respective ridge along the ridge axial length; the forward linear segment portions defining a forward zone and the aft linear segment portions defining an aft zone; the respective ridge pattern of indentations enhancing higher hot working gas erosion resistance in the forward zone than in the aft zone; and enhancing greater porosity and abradability in the aft zone than in the forward zone. ### Claim 2 (depends on 1) The component of claim 1, the pattern of indentations having increasing volumes axially along the ridge from proximate the upstream axial end of the support surface to proximate the downstream axial end of the support surface. ### Claim 3 (depends on 1) The component of claim 1, the indentations having varying cross sectional profile, for varying indentation volume. ### Claim 4 (depends on 1) The component of claim 1, the indentations having varying depth, for varying indentation volume. ### Claim 5 (depends on 1) The component of claim 1, the indentation pitch spacing varying axially along the ridge. ### Claim 6 (depends on 1) The component of claim 1, the forward zone ridges respectively having monolithic, featureless surfaces with no indentations, and the aft zone ridges having a pattern of indentations. ### Claim 7 (depends on 6) The component of claim 6, the forward zone ridges comprising approximately one-third of each ridge axial length. ### Claim 8 (depends on 1) The component of claim 1, the forward zone ridges comprising approximately one-third of each ridge axial length. ### Claim 9 (depends on 1) The component of claim 1, the forward and aft segments defining a hockey stick plan form pattern. ### Claim 10 A turbine engine, comprising: a turbine housing including a turbine casing interior circumference; a rotor having blades rotatively mounted in the turbine housing along a turbine blade rotational axis, distal tips of which forming a blade tip circumferential swept path in the blade rotation direction and axially with respect to the turbine casing interior circumference, each turbine blade having a leading edge, a mid-chord cutoff point on its pressure side concave surface and a trailing edge, oriented at a trailing edge angle relative to turbine blade rotational axis; and a ring segment component having: a curved support surface coupled to the turbine casing inner circumference outwardly circumscribing the rotating turbine blade airfoil tips and the turbine blade rotational axis, the support surface having upstream and downstream axial ends and a support surface curvature radius defined by a support surface central axis that is parallel to the turbine blade rotational axis; an abradable substrate coupled to the support surface, having a substrate surface with a plan form pattern of grooves and vertically projecting ridges facing the support surface central axis, the grooves and ridges originating and terminating axially between the support surface ends and defining forward and aft segment portions; the forward segment portion originating nearer the support surface upstream end, and defining a forward zone; the aft segment portion originating at the adjoining forward segment termination and terminating nearer the support surface downstream end, and defining an aft zone; a pattern of indentations respectively having cross sectional profiles and depth, formed in the ridges, for selectively varying porosity and/or abradability of the respective ridge along the ridge axial length; the respective ridge pattern of indentations enhancing higher hot working gas erosion resistance in the forward zone than in the aft zone; and enhancing greater porosity and abradability in the aft zone than in the forward zone. ### Claim 11 (depends on 10) The turbine engine of claim 10, the forward zone having axial length defined between approximately one-third and one-half of a corresponding turbine blade airfoil axial length, and the aft zone defining remaining ridge axial length between support surface the axial ends. ### Claim 12 (depends on 11) The turbine engine of claim 11, the forward zone pattern axial length terminating opposite axial position of the turbine blade mid-chord cutoff, and the aft zone pattern defining remaining ridge axial length. ### Claim 13 (depends on 10) The component of claim 10, the pattern of indentations having increasing volumes axially along the ridge from proximate the upstream axial end of the support surface to proximate the downstream axial end of the support surface. ### Claim 14 (depends on 13) The component of claim 13, the indentations having varying cross sectional profile, for varying indentation volume. ### Claim 15 (depends on 13) The component of claim 13, the indentations having varying depth, for varying indentation volume. ### Claim 16 (depends on 13) The component of claim 13, the indentation pitch spacing varying axially along the ridge. ### Claim 17 (depends on 10) The component of claim 10, the forward zone ridges respectively having monolithic, featureless surfaces with no indentations, and the aft zone ridges having a pattern of indentations. ### Claim 18 (depends on 17) The turbine engine of claim 17, the forward zone pattern axial length terminating opposite axial position of the turbine blade mid-chord cutoff, and the aft zone pattern defining the remaining axial length. ### Claim 19 A method for enhancing operational service life of a turbine engine, comprising: providing a turbine engine, having: a turbine housing including a turbine casing interior circumference; a rotor having blades rotatively mounted in the turbine housing along a turbine blade rotational axis, distal tips of which forming a blade tip circumferential swept path in the blade rotation direction and axially with respect to the turbine casing interior circumference, each turbine blade having a leading edge, a mid-chord cutoff point on its pressure side concave surface and a trailing edge, oriented at a trailing edge angle relative to turbine blade rotational axis; and a ring segment component having: a curved support surface coupled to the turbine casing inner circumference outwardly circumscribing the rotating turbine blade airfoil tips and the turbine blade rotational axis, the support surface having upstream and downstream axial ends and a support surface curvature radius defined by a support surface central axis that is parallel to the turbine blade rotational axis; an abradable substrate coupled to the support surface, having a substrate surface with a plan form pattern of grooves and vertically projecting ridges facing the support surface central axis, the grooves and ridges originating and terminating axially between the support surface ends and defining forward and aft segment portions; the forward segment portion originating nearer the support surface upstream end, and defining a forward zone; the aft segment portion originating at the adjoining forward segment termination and terminating nearer the support surface downstream end, and defining an aft zone; and forming a pattern of indentations in the ridges, the indentations respectively having cross sectional profiles and depth, for selectively varying porosity and/or abradability of the respective ridge along the ridge axial length; the respective ridge pattern of indentations enhancing higher hot working gas erosion resistance in the forward zone than in the aft zone; and enhancing greater porosity and abradability in the aft zone than in the forward zone. ### Claim 20 (depends on 19) The method of claim 19, further comprising: terminating the forward zone ridges axial length opposite axial position of the turbine blade mid-chord cutoff; forming the forward zone ridges as monolithic, featureless surfaces with no indentations; and varying indentation pitch spacing and/or indentation volume axially along the ridge aft segment portion to proximate the downstream axial end of the support surface.