Acoustics and Thrust of Quiet Separate-Flow High-Bypass-Ratio Nozzles

摘要: TheNASAGlennResearchCenterrecentlycompletedanexperimentalstudytoreducethejetnoisefrommodern turbofan engines. The study concentrated on exhaust nozzle designs for high-bypass-ratio These modie ed the core and fan nozzles individually simultaneously. In comparison with chevrons, tabs appeared to be an inefe cient method reducing jet noise. Data trends show that interaction between e ow cowl could strongly impact noise cruise performance irrespective of mixing device installed. demonstrates cations are generally more advantageous than nozzle. Even greater advantage in reduction associated thrust penalties is demonstrated through simultaneous cation both nozzles. Thebestnozzledesign had a 0.06% cruisethrustlossand, corrected fortakeoff loss, 2.7-EPNdB effective perceived level metric. This design simultaneously employed chevrons Last, ve cone gurations loss less 0.5% reductions over 2.5 EPNdB identie as candidates full-scale engine ight demonstrations.