Turbine shroud with abradable layer having dimpled forward zone

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 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 facing the support surface central axis, the substrate surface defining a forward zone originating nearer the support surface upstream end and terminating axially between the support surface ends, and the substrate surface defining an aft zone originating at the adjoining forward zone termination and terminating axially nearer the support surface downstream end;
• the forward zone defining a plan form pattern of projection or indentation dimples facing the support surface central axis, the dimples respectively having cross sectional profiles, for selectively varying hot working gas erosion resistance, porosity and/or abradability thereof, the dimples further having increasing volumes axially along the abradable surface from proximate the upstream axial end of the support surface to proximate the downstream axial end of the support surface;
• the aft zone defining a plan form pattern of grooves and vertically projecting ridges facing the support surface central axis, angularly oriented at a first forward angle transverse to the support surface central axis and opposite corresponding turbine blade rotational direction;
• the respective forward zone dimple pattern enhancing higher hot working gas erosion resistance than in the aft zone;
• and the respective aft zone ridge and groove pattern enhancing greater porosity and abradability than in the forward zone.

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 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 facing the support surface central axis, the substrate surface defining a forward zone originating nearer the support surface upstream end and terminating axially between the support surface ends, and the substrate surface defining an aft zone originating at the adjoining forward zone termination and terminating axially nearer the support surface downstream end;
• forming in the forward zone a plan form pattern of projection or indentation dimples facing the support surface central axis, the dimples respectively having cross sectional profiles, the dimples further having increasing volumes axially along the abradable surface from proximate the upstream axial end of the support surface to proximate the downstream axial end of the support surface;
• and
• forming in the aft zone a plan form pattern of grooves and vertically projecting ridges facing the support surface central axis, angularly oriented at a first forward angle transverse to the support surface central axis and opposite corresponding turbine blade rotational direction, for selectively varying hot working gas erosion resistance, porosity and/or abradability thereof;
• the respective forward zone dimple pattern enhancing higher hot working gas erosion resistance than in the aft zone and the respective aft zone ridge and groove pattern enhancing greater porosity and abradability than in the forward zone.