US Patent 8702378 Air flow passage liner

A liner is provided for an air flow passage of a gas turbine engine. The liner comprises an acoustic attenuation layer which forms an air-washed surface of the flow passage, and a heat exchanger layer which extends as a backing to the acoustic attenuation layer. The heat exchanger layer is configured to carry a heated fluid flow and to transport heat from the fluid flow to the acoustic attenuation layer from where the heat is transferred to air flowing through the air flow passage.