#lxvce

The sawtooth trailing edge of the Boeing 747-8 family or nacelle chevrons are for noise reduction- during the design phase, computational fluid dynamics was used to optimize the shape and cant of the chevrons- each tip is canted inward slightly into the bypass flow. ⠀ ⠀ Jet exhaust noise is the result of turbulence in the exhaust flow. ⠀ ⠀ Each chevron tip creates a vortex that speeds the mixing of the cooler bypass flow with the hot core flow, reducing the turbulence from the mixing of the two flows- but CFD was needed to optimize the chevrons as too much of a vortex could cause more turbulence and actually increase noise. ⠀ ⠀ A Boeing 777 flew with a testbed chevron nacelle to validate the CFD work under the Quiet Technology Demonstrator program. The 747-8 and 787 were beneficiaries of the QTD program and on the 747-8 family, the chevrons reduce engine noise by a significant 4 dB. As the nose decibel scale is logarithmic and not linear, a 4 dB reduction in engine noise is remarkable.⠀ ⠀ The GEnx (General Electric NeXt generation) engine used on the 747-8 family first ran in 2006 and is the replacement in the GE turbofan portfolio for the CF6-80C2. Used on both the Boeing 787 and the 747-8i/8F, the GEnx is an advanced evolution of the GE90 turbofan used on the Boeing 777. ⠀ ⠀ With significant aerodynamic and materials improvements, the GEnx engines on the Boeing 747-8i/8F have a 15% better fuel burn than the CF6-80C2. Much of what went into the GEnx engine is also used on the CFM LEAP-X engine.⠀ ⠀ November Aviation Photo Challenge | @kjdphoto1971 | #1119planes | “Takeoff/Landing” | Day 21⠀ ⠀ #Avgeek #aviation #aircraft #planeporn #KDFW #DFW #airport #igTexas #planespotting #airlines #Boeing #747 #Cargolux #dfwavgeek #instagramaviation #LXVCE #splendid_transport #instaaviation #aviationlovers #aviationphotography #flight #aviationphotography #AvgeekSchoolofKnowledge #AvGeeksAero #AvGeekNation (at DFW Airport) https://www.instagram.com/p/B5IKVVyBdhh/?igshid=ha5jne8t2keh

The sawtooth trailing edge of the Boeing 747-8 family or nacelle chevrons are for noise reduction- during the design phase, computational fluid dynamics was used to optimize the shape and cant of the chevrons- each tip is canted inward slightly into the bypass flow. Jet exhaust noise is the result of turbulence in the exhaust flow. Each chevron tip creates a vortex that speeds the mixing of the cooler bypass flow with the hot core flow, reducing the turbulence from the mixing of the two flows- but CFD was needed to optimize the chevrons as too much of a vortex could cause more turbulence and actually increase noise. A Boeing 777 flew with a testbed chevron nacelle to validate the CFD work under the Quiet Technology Demonstrator program. The 747-8 and 787 were beneficiaries of the QTD program and on the 747-8 family, the chevrons reduce engine noise by a significant 4 dB. As the nose decibel scale is logarithmic and not linear, a 4 dB reduction in engine noise is remarkable. #Avgeek #aviation #aircraft #planeporn #KDFW #DFW #airport #igTexas #planespotting #airlines #Boeing #747 #Cargolux #DFWavgeek #instagramaviation #LXVCE #splendid_transport #instaaviation #Avgeekery #AvgeekSchoolofKnowledge (at DFW Founders Plaza)