Aeroacoustic Analysis of Asymmetric Lift-Offset Helicopter in Forward Flight

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dc.contributor.advisorBaeder, Jamesen_US
dc.contributor.authorArias, Pauloen_US
dc.contributor.departmentAerospace Engineeringen_US
dc.contributor.publisherDigital Repository at the University of Marylanden_US
dc.contributor.publisherUniversity of Maryland (College Park, Md.)en_US
dc.date.accessioned2022-02-04T06:32:50Z
dc.date.available2022-02-04T06:32:50Z
dc.date.issued2021en_US
dc.description.abstractIn recent years, the University of Maryland has worked on an asymmetric lift-offset compound helicopter. The configuration consists of a single main rotor helicopter with the addition of two key ways to increase the forward speed: a stubbed wing on the retreating fuselage side, and a slowed down rotor. Experiments and simulations have shown that the novel concept provides improved thrust potential and lift-to-drag ratios in high-speed forward flight. This study aims to determine whether the asymmetric lift-offset configuration also provides aeroacoustic benefits in forward flight in addition to its aerodynamic advantages. The aerodynamic results from previous computational and experimental studies are recreated using the Mercury framework, in-house Computational Fluid Dynamics solver based on Reynolds-Averaged Navier-Stokes (RANS) coupled to a comprehensive rotor analysis for structural deformations and trim. The acoustic analysis is performed using an acoustic code based on the Ffowcs William-Hawkings equation to solve for the tonal noise propagating from the surfaces of the aircraft. The BPM model is used for broadband noise prediction. It was found that for an advance ratio of 0.5 the wing-lift offset configuration can produce 56.8% more thrust at the same collective angle without any penalties in total noise. When the configurations produce equal thrust it was found that the wing-lift offset case has a 4 dB reduction in maximum overall sound pressure level. At an advance ratio of 0.3 with trim for equivalentthrust between configurations, a 3 dB maximum OASPL reduction was obtained with the inclusion of the wing. The rotor of the wing-lift offset case was also slowed down while maintaining equal thrust to find a 6 dB reduction at an advance ratio of 0.55. Blade flap and lag bending moments near the root were also significantly reduced for the wing-lift offset configuration with equal thrust.en_US
dc.identifierhttps://doi.org/10.13016/avxz-opjn
dc.identifier.urihttp://hdl.handle.net/1903/28413
dc.language.isoenen_US
dc.subject.pqcontrolledAerospace engineeringen_US
dc.subject.pqcontrolledAcousticsen_US
dc.subject.pquncontrolledAcousticsen_US
dc.subject.pquncontrolledCompounden_US
dc.subject.pquncontrolledCouplingen_US
dc.subject.pquncontrolledHelicopteren_US
dc.subject.pquncontrolledLift-Offseten_US
dc.subject.pquncontrolledNoiseen_US
dc.titleAeroacoustic Analysis of Asymmetric Lift-Offset Helicopter in Forward Flighten_US
dc.typeThesisen_US

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