Gas turbine engine with carbon/carbon composite piston seal

A method for processing a seal for a gas turbine engine, the method comprising:

• providing a carbon fiber preform;
• densifying the carbon fiber preform with a carbon matrix and forming a carbon/carbon composite ring;
• and
• forming a seal by cutting the carbon/carbon composite ring to form at least one seam at which opposed ends of the carbon/carbon composite ring meet, the seal having a multi-layer configuration of fiber plies in an axially stacked arrangement such that planes in which the fiber plies lie are perpendicular to a central axis of the carbon/carbon composite ring.

A gas turbine engine comprising:

• a rotor rotatable about an engine central axis and defining a seal surface;
• a shaft rotatable about the engine central axis, the shaft defining an annular seal channel that opens to the seal surface;
• and
• a seal disposed in the annular seal channel for sealing against the seal surface, the seal being made of a composite having carbon fibers disposed in a carbon matrix, the seal having a configuration selected from the group consisting of
• (a) a multi-layer configuration of fiber plies in a radially stacked arrangement,
• (b) a layer-less configuration in which the carbon fibers are not provided in fiber plies, the carbon fibers have a unidirectional orientation, and the carbon fiber plies extend circumferentially,
• (c) a configuration in which the carbon fibers are in flat tows that are elongated in directions that are oblique to the engine central axis,
• (d) a configuration including an annular core that extends along a central core axis that extends circumferentially around the engine central axis and the carbon fibers are in flat tows that are would around the central core axis on the annular core, and
• (e) a configuration in which the seal extends along a seal axis that extends circumferentially around the engine central axis, and the carbon fibers are in strands that are braided around the seal axis.