Space-filling design of experiments are performed on the Environmental Design Space (EDS) architecture to enable an understanding of the sensitivity of various noise-metrics to vehicle-level design variables. These include aerodynamic, propulsion, and airframe design variables. Half-normal probability plots are used to show that airframe design variables dominate approach noise, while design variables related to bypass ratio have the greatest influence on departure noise. These results are consistent for both NPD-curves and soundexposure-level (SEL) contour areas, but not for the certification effective-perceived-noiselevel (EPNL) metrics or Maximum A-weighted Sound Level (L Amax ) based spectra, which demonstrate some unique sensitivities. Interdependencies of noise, fuel burn, and NO x emissions metrics are also explored. Nomenclature AEDT = Aviation Environmental Design ToolANOPP = Aircraft Noise Prediction Program ASDL = Aerospace Systems Design Laboratory CAEP = Committee on Aviation Environmental Protection CDA = Constant Descent Angle CMPGEN = Fan and Compressor Component Map Generating Tool dB = Decibels DNL = Day-Night-Average Level DOE = Design of Experiments EDS = Environmental Design Space EPA = Environmental Protection Agency EPNL = Effective Perceived Noise Level FAA = Federal Aviation Administration FLOPS = Flight Optimization System ICAO = International Civil Aviation Organization INM = Integrated Noise Model L Amax = Maximum A-Weighted Sound Level LHC = Latin Hypercube
Successful mitigation of aviation noise is a key enabler for sustainable aviation growth. A key focus of this effort is the noise arising from aircraft arrival operations. Arrival operations are characterized by the use of high-lift devices, deployment of landing gear, and low thrust levels, which results in the airframe being the major component of noise. In order to optimize for arrival noise, management of the flap schedule and gear deployment is crucial. This research aims to create an optimization framework for evaluating various aircraft trajectories in terms of their noise impact. A parametric representation of the aircraft arrival trajectory will be created to allow for the variation of aircraft's flap schedule. The Federal Aviation Administration's Aviation Environmental Design Tool will be used to simulate the aircraft trajectory and performance, and to compute the noise metrics. Specifically, the latest performance model from EUROCONTROL called "Base of Aircraft Data - Family 4" will be used. This performance model contains higher fidelity modeling of aircraft aerodynamics and other characteristics which allows for better parametric variation.
Rotorcraft with a teetering rotor design are susceptible to a phenomenon known as "mast bumping" or "excessive flapping" which can lead to severe shaft structural damage followed by total separation of the rotor from the vehicle and a potential incursion of the rotor blade into the fuselage. Mast bumping accidents are nearly always fatal and are generally unavoidable once specific flight conditions are met. Certain teetering rotor vehicles are prohibited from specific maneuvers that may lead to mast bumping events. However, specific incidents indicate that certain causes of mast bumping may have not yet been determined, and the extreme danger of the phenomenon makes studies using flight testing impossible. This research uses the Rotorcraft Comprehensive Analysis System (RCAS) to create a physics-based, parameterized model of a nominal teetering rotor helicopter to simulate and assess the mast bumping risk of various level flight conditions and specific maneuvers. This data is used to develop a metric to quantify the mast bumping risk of any maneuver. This model is also used to study the sensitivity of a vehicles mast bumping tendency to conceptual rotor design parameters. Preliminary analyses show a relationship between mast bumping risk and high airspeed, as well as low g-force. Studies on variations in blade mass properties indicate that increasing the blade mass or placing the blade CG farther towards the tip increases mast bumping risk in low speed flight regimes.
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