1. A heat transfer apparatus for a gas turbine engine, comprising:
a component having a wall structure defining a flow bounding surface; and a chamber formed in the component, the chamber including a wicking structure, a vapor channel, and a working fluid.
2. The apparatus as claimed in claim 1 wherein the chamber is integrally
formed with the wall structure.
3. The apparatus as claimed in claim 2 wherein the wall structure transitions from a solid structure at the flow bounding surface to a permeable structure at an inner surface.
4. The apparatus as claimed in claim 1 wherein the wall structure comprises a three-dimensional mass having an array of spaced-apart, mutually perpendicular holes passing therethrough.
5. The apparatus as claimed in claim 4 wherein the holes are arranged in
two or more layers, the holes of each layer having different diameters.
6.The apparatus as claimed in claim 1 wherein the component includes an airfoil having opposed pressure and suction sidewalls, a root, a tip, and spaced-apart leading and trailing edges.
7. The apparatus as claimed in claim 6 wherein the chamber extends
beyond the root or the tip of the airfoil.
8. The apparatus as claimed in claim 6 wherein:
the wicking structure spans the space between the sidewalls; and
a series of spanwise vapor channels extend through the wicking structure.

9. The apparatus as claimed in claim 6 wherein:
the wicking structure spans the space between the sidewalls; and a spanwise vapor channel having an airfoil-shaped cross-section extends through a central portion of the wicking structure.
10. The apparatus as claimed in claim 6 wherein:
a plurality of supports extend transversely between the pressure and suction sidewalls; and
at least a portion of at least one of the supports comprises a permeable material defining a part of the wicking structure.
11. The apparatus as claimed in claim 1, wherein a portion of the chamber
extends beyond the remainder of the component; and
a sump enclosing the extended portion of the chamber and configured for circulation of a fluid therethrough.
12. The apparatus as claimed in claim 1, wherein a portion of the chamber
extends beyond the remainder of the component; and
a fluid conduit is disposed in contact with the extended portion of the chamber.
13. The apparatus as claimed in claim 12 wherein:
the fluid conduit has an annular outer wall; and
the extended portion of the chamber has a concave saddle shape that contacts the outer wall of the fluid conduit.
14. The apparatus as claimed in claim 1, wherein a portion of the chamber
extends beyond the remainder of the component; and a stub portion of a fluid
conduit is formed as part of a single monolithic structure with the extended

portion of the chamber.
15. A heat transfer apparatus for a gas turbine engine, comprising:
a plurality of components arranged in a ring around the engine and extending in a generally radial direction so as to define opposed inboard and outboard ends, each component having:
a wall structure defining a flow bounding surface; and
a chamber formed in the component, the chamber including a wicking structure, a vapor channel, and a working fluid, wherein the chamber includes an evaporator end and an opposed condenser end;
wherein, for some of the chambers, the evaporator end is positioned at the inboard end of the corresponding component, and for others of the chambers, the evaporator end is positioned at the outboard end of the corresponding component.
16. The apparatus as claimed in claim 15 wherein the evaporator end of each chamber is positioned such that gravity will assist fluid flow from the condenser end to the evaporator end, for a predetermined orientation of the engine.
17. The apparatus as claimed in claim 15 wherein the components are guide vanes.