Abstract: Disclosed is a gas turbine engine including a fan, a nacelle including a flutter damper forward of the fan, the flutter damper including an acoustic liner having a perforated radial inner face sheet and a radial outer back sheet, the acoustic liner configured for peak acoustical energy absorption at a frequency range that is greater than a frequency range associated with fan flutter, a chamber secured to the radial outer back sheet, the chamber in fluid communication with the acoustic liner, and the chamber configured for peak acoustical energy absorption at a frequency range associated with fan flutter modes, and the engine includes (i) the nacelle and a core cowl forming a convergent-divergent fan exit nozzle; (ii) a variable area fan nozzle capable of being in an opened and closed, the opened position having a larger fan exit area than the closed position; and/or (iii) the fan being shrouded.

Abstract: Disclosed is a gas turbine engine including a fan, a nacelle including a flutter damper forward of the fan, the flutter damper including an acoustic liner having a perforated radial inner face sheet and a radial outer back sheet, the acoustic liner configured for peak acoustical energy absorption at a frequency range that is greater than a frequency range associated with fan flutter, a chamber secured to the radial outer back sheet, the chamber in fluid communication with the acoustic liner, and the chamber configured for peak acoustical energy absorption at a frequency range associated with fan flutter modes, and the engine includes (i) the nacelle and a core cowl forming a convergent-divergent fan exit nozzle; (ii) a variable area fan nozzle capable of being in an opened and closed, the opened position having a larger fan exit area than the closed position; and/or (iii) the fan being shrouded.

Abstract: A compact heat exchanger system 52 for a duct 32 of a gas turbine engine 10 is disclosed, the heat exchanger system being disposed between two locations having an adverse pressure gradient. Various construction details which reduce the impact of the system 52 on engine efficiency, provide acceptable levels of drag, and reduce the possibility of foreign object damage are developed. In one embodiment the system has a low profile inlet 58 adjacent the inner wall 36 of a fan duct and has a flow path 56 extending from the inlet 58 to the outlet 62 which is continuous under all operating conditions of the engine.

Abstract: An inlet-outlet module 108 having both an inlet 58 and an outlet 62 for a heat exchanger system 52 is disclosed. Various construction details which improve the stiffness to weight ratio and the aerodynamic smoothness are developed. In one embodiment, the module 108 is formed of a one piece casting having a lobed mixer 94 at the outlet.