Blade outer air seal

1. A method for manufacturing a turbine engine blade outer air seal segment, the method including a reengineering from a baseline configuration and the segment comprising:

a body having:

a base portion having:

a transversely concave ID face;

a plurality of outlet holes extending through the base portion to the ID face;

a forward end;

an aft end; and

first and second circumferential edges; and

at least one mounting hook; and

at least one cover plate secured to the body to define at least one cavity and having a plurality of feed holes through the cover plate,

wherein:

at least one of the base portion and cover plate comprises at least one protruding portion protruding into the cavity to form at least partial restrictions separating circumferentially and fore-aft offset compartment portions; and

at least some of the feed holes are upstream of a given one of the at least one protruding portion and at least some of the feed holes are downstream of said given one of the at least one protruding portion,

the method comprising;

determining an indication of an operational core flow pressure drop along the ID face;

selecting a characteristics of the protruding portion to provide a fore-aft pressure drop within the cavity, wherein a distribution of the feed holes in the plate is shifted forward relative to the baseline configuration;

manufacturing the protruding portion with said characteristic via stamping;

manufacturing the body via casting; and

securing the cover plate to the body.

2. The segment of claim 1 further comprising:

a coating on the base portion ID face.

3. The apparatus of claim 1 wherein:

the at least one mounting hook includes:

at least one front mounting hook; and

at least one aft mounting hook.

4. The apparatus of claim 1 wherein the at least one protruding portion comprises:

at least one blister on the cover plate.

5. The segment of claim 4 further comprising:

a coating on the base portion ID face.

6. The apparatus of claim 1 wherein:

the cover plate is a stamping;

the body is a casting having a thermal barrier coating on the ID face; and

the cover plate is welded to the body.

7. A turbine engine blade outer air seal segment comprising:

a body having:

a base portion having:

a transversely concave ID face;

a forward end;

an aft end; and

first and second circumferential edges; and

at least one mounting hook; and

at least one cover plate secured to the body to define at least one cavity and having a plurality of feed holes, a plurality of outlet holes extending through the base portion to the ID face,

wherein:

at least one of the base portion and cover plate comprises at least one protruding portion protruding into the cavity to form at least partial restrictions separating circumferentially and fore-aft offset compartment portions; and

the at least one protruding portion comprises:

an essentially full height axial rib of the body;

a partial height circumferential rib of the body, the axial rib and circumferential rib cooperating to divide the compartment into four quadrants; and

four circumferentially elongate blisters on the cover plate, each along a respective one of the four quadrants.

8. The apparatus of claim 7 wherein the at least one protruding portion consists essentially of:

said axial rib;

said circumferential rib; and

said four circumferentially elongate blisters.

9. A turbine engine blade outer air seal segment comprising:

a body having:

a base portion having:

a transversely concave ID face;

a forward end;

an aft end; and

first and second circumferential edges; and

at least one mounting hook; and

at least one cover plate secured to the body to define at least one cavity and having a plurality of feed holes, a plurality of outlet holes extending through the base portion to the ID face,

wherein:

at least one of the base portion and cover plate comprises at least one protruding portion protruding into the cavity to form at least partial restrictions separating circumferentially and fore-aft offset compartment portions; and

the at least one protruding portion comprises:

a partial height axial rib of the body

an essentially full height circumferential rib of the body, the axial rib and circumferential rib cooperating to divide the compartment into four quadrants;

four circumferentially elongate blisters on the cover plate, each along a respective one of the four quadrants; and

four axially elongate blisters on the cover plate, each along a respective one of the four quadrants.

10. The apparatus of claim 9 wherein:

each of said four axially elongate blisters is positioned between said axial rib and an associated one of the circumferentially elongate blisters.

11. The apparatus of claim 9 wherein the axial rib is a first axial rib and the at least one protruding portion further comprises:

a second partial height axial rib on a first side of the first axial rib; and

a third partial height axial rib on a first side of the first axial rib.

12. The apparatus of claim 11 wherein the at least one protruding portion consists essentially of:

said first, second, and third axial ribs;

said circumferential rib;

said four circumferentially elongate blisters; and

said four axially elongate blisters.

13. A method for manufacturing a turbine engine blade outer air seal segment, the method including a reengineering from a baseline configuration and the segment comprising:

a body having:

a base portion having:

a transversely concave ID face;

a forward end;

an aft end; and

first and second circumferential edges; and

at least one mounting hook; and

at least one cover plate secured to the body to define at least one cavity and having a plurality of feed holes, a plurality of outlet holes extending through the base portion to the ID face, wherein:

at least one of the base portion and cover plate comprises means for providing an operational axial/circumferential pressure gradient within the cavity to compensate for an operational core flow pressure drop along the ID face,

the method comprising;

determining an indication of an operational core flow pressure drop along the ID face;

selecting a characteristic of the protruding portion to provide a fore-aft pressure drop within the cavity, wherein a distribution of the feed holes in the plate is shifted forward relative to the baseline configuration;

manufacturing the protruding portion with said characteristic via stamping;

manufacturing the body via casting; and

securing the cover plate to the body.

14. The segment of claim 13 wherein:

the means comprises a constriction of the cavity; and

at least some of the feed holes are upstream of the at least one constriction and at least some of the feed holes are downstream of the at least one constriction.

15. A method for manufacturing a turbine engine blade outer air seal segment including reengineering a configuration of a turbine engine blade outer air seal segment from a baseline configuration to a reengineered configuration, the baseline configuration comprising:

a body having:

a base portion having:

a transversely concave ID face; a forward end; an aft end; and

first and second circumferential edges; and

at least one mounting hook; and

at least one cover plate secured to the body to define at least one impingement cavity and having a plurality of feed holes, a plurality of outlet holes extending through the base portion to the ID face, the method comprising:

determining an indication of an operational core flow pressure drop along the ID face;

selecting a characteristic of the protruding portion to provide a fore-aft pressure drop with the cavity;

adding a protrusion into the cavity from at least one of the cover plate and base portion in the reengineering;

manufacturing the at least one of the cover plate and base portion with the protrusion;

and

securing the at least one of the cover plate and base portion to the other of the cover plate and base portion, wherein:

the baseline configuration has a mean location of the feed holes; and the reengineered configuration has a mean location of the feed holes forward of the baseline configuration mean location.

16. The method of claim 15 wherein:

the protrusion comprises a blister; and

at least some of the feed holes are upstream of the at least one protrusion and at least some of the feed holes are downstream of the at least one protrusion.

17. The method of claim 15 wherein:

relative to the baseline configuration, the reengineered configuration has a reduced cooling air requirement for a given level of cooling.