BLADE OUTER AIR SEAL HAVING SURFACE LAYER WITH POCKETS
A blade outer air seal includes a seal arc segment that has a surface layer and an array of internal pockets. The surface layer defines a radially inner side of the seal arc segment. The surface layers conformal with the array of internal pockets such that the surface layer includes an array of ridges that correspond in location and shape to the array of internal pockets.
1 . A blade outer air seal comprising:
a seal arc segment having a surface layer and an array of internal pockets, the surface layer defining a radially inner side of the seal arc segment, the surface layer being conformal with the array of internal pockets such that the surface layer includes an array of ridges corresponding in location and shape to the array of internal pockets.
2 . The blade outer air seal as recited in claim 1 , wherein the internal pockets are void.
3 . The blade outer air seal as recited in claim 1 , wherein, exclusive of any internal micro-porosity in the seal arc segment, the internal pockets are non-surface connected.
4 . The blade outer air seal as recited in claim 1 , wherein the internal pockets are interconnected.
5 . The blade outer air seal as recited in claim 1 , wherein the internal pockets contain silicon carbide.
6 . The blade outer air seal as recited in claim 1 , wherein the surface layer is formed of a thermal barrier material selected form the group consisting of metal oxides, silicates, and combinations thereof.
7 . The blade outer air seal as recited in claim 1 , wherein the surface layer is formed of a metal alloy.
8 . The blade outer air seal as recited in claim 1 , wherein the surface layer is selectively frangible such that upon break-away of the array of ridges of the surface layer, a pattern corresponding to the array of internal pockets remains.
9 . The blade outer air seal as recited in claim 1 , wherein the surface layer has a radial layer thickness defined between tips of the ridges and a distinct radially outer side of the surface layer, the ridges have a radial ridge thickness defined between the tips of the ridges and bases of the ridges, and the radial ridge thickness is at least 25% of the radial layer thickness.
10 . The blade outer air seal as recited in claim 1 , wherein the ridges are circumferentially elongated.
11 . A gas turbine engine comprising:
a rotor including a row of rotor blades rotatable about an axis; and
a blade outer air seal radially outwards of the row of rotor blades, the blade outer air seal including a plurality of seal arc segments, each of the plurality of seal arc segments having a surface layer and an array of internal pockets, the surface layer defining a radially inner side of the seal arc segment, the surface layer being conformal with the array of internal pockets such that the surface layer includes an array of ridges corresponding in location and shape to the array of internal pockets.
12 . The gas turbine engine as recited in claim 11 , wherein the internal pockets are void.
13 . The gas turbine engine as recited in claim 11 , wherein, exclusive of any internal micro-porosity in the seal arc segment, the internal pockets are non-surface connected.
14 . The gas turbine engine as recited in claim 11 , wherein the internal pockets are interconnected.
15 . The gas turbine engine as recited in claim 11 , wherein the internal pockets contain silicon carbide.
16 . The gas turbine engine as recited in claim 11 , wherein the surface layer has a radial layer thickness defined between tips of the ridges and a distinct radially outer side of the surface layer, the ridges have a radial ridge thickness defined between the tips of the ridges and bases of the ridges, and the radial ridge thickness is at least 25% of the radial layer thickness.
17 . A method for fabricating a blade outer air seal, the method comprising:
providing template on a seal arc segment; and
applying a surface layer over the template to form a radially inner side of the seal arc segment, the surface layer conforming with the template to produce an array of internal pockets occupied by the template and an array of ridges corresponding in location and shape to the array of internal pockets.
18 . The method as recited in claim 17 , further comprising thermally removing the template such that the pockets are void.
19 . The method as recited in claim 17 , wherein the template is formed of graphite.
20 . The method as recited in claim 17 , wherein the template is formed of silicon carbide.