Abstract: A compressor bleed air passageway includes a duct having an upstream section (48) which terminates in a baffle (44) and a downstream duct section (54) having a forward portion (56) which surrounds the baffle (44). Bleed air flow through openings (58) in the baffle wall (52). This reduces velocity of the bleed air stream at the duct discharge port to a value equal to or less than Mach 1.0. The baffle (44) has virtually no effect on a low-velocity, low-pressure air stream. The downstream duct section (54) may be perforated and surrounded by outer wall (64) to form sound-absorbing chambers (66).

Abstract: A high efficiency broadband acoustic resonator and absorption panel used for reducing engine noise from high bypass fan jet engines mounted on an aircraft. The panel uses a single layer of cellular honeycomb core with a pair of parallel acoustic septums formed internally in the core for attenuating high and medium frequency sounds during all engine operations as well as the low frequency combination tone and "buzzsaw" noise experienced during high power aircraft takeoff and cutback engine power settings.