An Analytical Assessment of NASA's N+1 Subsonic Fixed Wing Project Noise Goal

Berton, Jeffrey J.; Envia, Edmane; Burley, Casey L.

doi:10.2514/6.2009-3144

Cited by 28 publications

(20 citation statements)

References 6 publications

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Section: Engine Cycle Benefitsmentioning

confidence: 99%

“…Figure 4 shows the theoretical reductions in the engine noise output as the bypass ratio is increased. 3 Of course, nacelle drag considerations, weight penalty, and the availability of the liner treatment area place practical limits on how large the bypass ratio of a turbofan engine can actually be.…”

Section: Engine Cycle Benefitsmentioning

confidence: 99%

“…13 to 18) were conducted between 1993 2 Bypass ratio is the fan bypass mass flow rate divided by the core mass flow rate. 3 The increase in the bypass ratio could potentially come at the expense of an increase in core noise (principally, compressor and turbine noise), but the overall noise reductions at present outweigh this potential penalty.NASA/TM-2012-217248 6 Clearly, the GTF test results have shown the significant potential of the ultra-high bypass ratio turbofan technology in reducing aircraft engine noise. In follow up work to the original GTF research, NASA and P&W are cooperatively working towards developing the second generation GTF fan design to further improve its aerodynamic performance margins while maintaining its noise margin (Ref.…”

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confidence: 99%

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Emerging Community Noise Reduction Approaches

Envia

2011

3rd AIAA Atmospheric Space Environments Conference

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An overview of the current NASA research portfolio in the area of aircraft noise reduction is presented. The emphasis of the research described herein is on meeting the aggressive near-and mid-term national goals for reducing aircraft noise emissions, which NASA internal studies have shown to be feasible using noise reduction technologies currently being developed in-house or in partnership with NASA's industry and academic partners. While NASA has an active research effort in airframe noise reduction, this overview focuses on propulsion noise reduction only. IntroductionReducing aircraft noise emissions is an important part of the ongoing efforts to mitigate the impact of commercial aviation on the environment. The anticipated growth of the commercial air traffic in the next two decades (forecast (Ref. 1) shown in Fig. 1) calls for the development of low-noise aircraft that can offset the projected increase in the community noise exposure. To address this challenge, NASA is pursuing aggressive aircraft noise reduction goals as part of a comprehensive set of national aeronautics goals shown in Table 1. The environmental goals can be traced to the National Aeronautics Research and Development Plan, which was approved in December of 2007 (Ref. 2). The designations "N+1," "N+2," and "N+3" denote three successive aircraft generations beyond the current one in service today. NASA is conducting research across all three aircraft generations.Clearly, meeting these noise goals requires significant reductions in the level of noise emissions from future aircraft compared to aircraft flying today. To highlight the magnitude of the challenge, Figure 2 shows the N+1 and N+2 noise goals in relation to the measured average noise level margin for a number of representative past and present generation commercial aircraft. Margin is the difference between the noise level that an aircraft generates at a given certification point and the level of allowable noise set by the noise regulation at that point, which is a function of the aircraft weight. Note that, since the national noise goals are expressed in terms of the cumulative margin (i.e., the sum of the margins at approach, flyover, and lateral certification points), to plot them on this graph, the average margin was taken to be one third of the cumulative margin.The dramatic change required to meet these goals is the motivation for the aircraft noise research that NASA has been conducting over the last five years. In fact, the Subsonic Fixed Wing (SFW) Project and, more recently, the Environmentally Responsible Aviation (ERA) Project have been funding fundamental and system level research in low-noise aircraft concepts and noise reduction technologies that could meet these aggressive goals for the future subsonic transport aircraft.1 Ultimately, the main objective of NASA's aircraft noise reduction research is to provide a portfolio of low-noise technologies that do not compromise the other performance aspects of an aircraft.An early outcome of this research campaign w...

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Section: Engine Cycle Benefitsmentioning

confidence: 99%

Section: Engine Cycle Benefitsmentioning

confidence: 99%

mentioning

confidence: 99%

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Emerging Community Noise Reduction Approaches

Envia

2011

3rd AIAA Atmospheric Space Environments Conference

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“…To do so, the Strategic Plan identifies five areas fundamental to the expansion of global civilian aviation, specifically improvements in passenger safety, throughput and mobility, as well as improvements in noise and emissions. suggests that while significant progress has been made, a "3EPNdB shortfall indicates that a slightly greater reliance on noise reduction technologies will be needed to achieve the goal" (11). The study uses a "notional airplane in the 'low-noise corner' of the design trade space," combining an inherently quiet engine design with "innovative, advanced, noise reduction technologies,"…”

Section: Nasa: Noisementioning

confidence: 99%

A Study of the Aeroelastic Behavior of Flat Plates and Membranes with Mixed Boundary Conditions in Axial Subsonic Flow

Bloomhardt

Dowell

2011

52nd AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics and Materials Conference

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In support of the noise reduction targets for future generations of transport aircraft, as set forth by NASA, the fundamental aeroelastic behavior of trailing edge flap technology was explored. Using a plate structural model to approximate the structural configuration and linear potential flow theory to represent the aerodynamics, aeroelastic behavior was characterized for two structural configurations using two different sets of boundary conditions for each. The two structural configurations considered were a) all edges fixed and b) leading and side edges fixed, trailing edge free. In each configuration both simply supported and clamped boundary conditions were considered. Results are compared to calculations presented in the literature for the all edges simply supported configuration.v

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“…4 Investigations to achieve the ambitious goals of the N+1 generation concentrate on the powerplant and its placement, as the general configuration is constrained to remain conventional. Increased powerplant diameter and the use of geared fan drives are expected as side effects of the need to increase efficiency and reduce noise.…”

Section: Introductionmentioning

confidence: 99%

Performance and Noise Trade-Offs on a Civil Airliner with Over-the-Wing Engines

Powell

Sóbester

Joseph

2011

49th AIAA Aerospace Sciences Meeting Including the New Horizons Forum and Aerospace Exposition

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Community noise has become a major consideration in the design of new aircraft. The noise generated by the engines has decreased over the generations to the extent that a whole-airframe approach is required now to achieve further significant reductions. One option is to install the engines over the wings so the airframe reflects the fan noise away from on-the-ground observers. However, in addition to good noise shielding performance, the position of the engine also has to satisfy aerodynamic efficiency criteria. We investigate the sensitivity of aerodynamic and acoustic performance metrics with respect to the positioning of the engine relative to the wing. More specifically, we trade drag computed via Reynolds-Averaged Navier Stokes simulations versus noise shielding performance, obtained experimentally through scale model tests conducted in an anechoic chamber. Surrogate models of both metrics are constructed, enabling their Pareto analysis on the specific case of a modified DLR F6 airframe geometry.

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An Analytical Assessment of NASA's N+1 Subsonic Fixed Wing Project Noise Goal

Cited by 28 publications

References 6 publications

Emerging Community Noise Reduction Approaches

Emerging Community Noise Reduction Approaches

A Study of the Aeroelastic Behavior of Flat Plates and Membranes with Mixed Boundary Conditions in Axial Subsonic Flow

Performance and Noise Trade-Offs on a Civil Airliner with Over-the-Wing Engines

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