Noise Scattering by the Blended Wing Body Airplane: Measurements and Prediction

Reimann, Craig A.; Tinetti, Ana F.; Dunn, M. H.

doi:10.2514/6.2006-2474

Cited by 13 publications

(8 citation statements)

References 10 publications

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“…A number of novel noise technologies with potential application for the BWB were investigated, with modest benefits. For instance, the distributed propulsion system in the centerbody enables substantial amount of acoustic treatment in the exhaust duct, such as the use of extensive acoustic liners [76,77]. Sakaliyiski et al [78] investigated the potential perforated drag plates, and Shah et al [79] proposed the treatment of the trailing edges by the deployment of brushes to reduce airframe self-noise, although the noise reductions were limited to 4 dB [80].…”

Section: Noisementioning

confidence: 99%

The U.S Air Force Next-Generation Air-Refueling System: a Resurgence of the Blended wing Body?

Fernandes,

Maldonado

2024

Preprint

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The interest in flying wings dates as far the early years of the aviation age. Over the 20th century, numerous attempts were made to investigate the feasibility of the concept, which demonstrated numerous early benefits: increased aerodynamic efficiency, reduced fuel consumption and lower noise and pollutant emissions compared to conventional tube and wing aircraft. However, major technical challenges prevented that type of design from entering mass production, especially with regards to structural design and manufacturing, stability and control and ride quality. In the 1990’s, a new concept, the blended wing body (BWB), was created to alleviate some of the concerns of flying wings while maintaining increased efficiency. Despite the promise, technical hurdles once again proved to be a deal breaker, and as of 2024, the only flying wing to enter serial production is the B-2 Spirit, an extremely complex and expensive aircraft. Thirty years later, as the world is quickly transitioning towards cleaner energy, the interest in the blended wing body has been renewed. The latest technological advancements in the aerospace industry should make the development of the BWB more plausible, however passenger comfort issues remain. Surprisingly, the BWB development may come from an unexpected application: as a tanker aircraft. As the U.S. Air Force is seeking a replacement to hundreds of aging tankers, a startup company was recently funded to develop the concept and build a prototype. In this study, we explore the history of blended designs from its early days, highlighting its opportunities and challenges – and why the design is an intriguing fit for application as a tanker aircraft.

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Section: Noisementioning

confidence: 99%

The U.S Air Force Next-Generation Air-Refueling System: a Resurgence of the Blended wing Body?

Fernandes,

Maldonado

2024

Preprint

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“…A post-test HWB assessment will demonstrate the viability of the HWB aircraft to achieve NASA's goals. But just as importantly, the results of this test will be used to update the shielding databases compiled over the last decade from the works of Clark and Gerhold 14 , Hill 15,16 , Reimann and Tinetti 17 , and most recently by Czech, Thomas, and Elkoby 18 , and to validate the scattering and diffraction codes.…”

Section: Background and Historymentioning

confidence: 99%

Hybrid Wing Body Aircraft Acoustic Test Preparations and Facility Upgrades

Heath¹,

Brooks²,

Hutcheson³

et al. 2013

AIAA Ground Testing Conference

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A hybrid wing body transport aircraft model was tested in NASA Langley's 14 by 22Foot Subsonic Tunnel to evaluate proposed "low noise" technology. The experiment was set up to evaluate the community noise impact of the hybrid wing body design, as well as study the noise components of propulsion-airframe noise and shielding. A high fidelity 5.8-percent scale model, including landing gear, cruise and drooped wing leading edges, trailing edge elevons, vertical tail options, and engine noise simulators, was built to test both aerodynamic and acoustic configurations. The aerodynamic test data were used to establish appropriate flight conditions for the acoustic test.To accomplish the acoustic portion of this test, two major upgrades were required of NASA Langley's 14 by 22 Foot Subsonic Tunnel; first, a fuel delivery system to provide realistic gas temperatures to the jet engine simulators; and second, a traversing microphone array and side towers to measure full spectral and directivity noise characteristics.The results of this test provide benchmark hybrid wing body aircraft and noise shielding data to assist in achieving NASA's 2020 noise emission goals. I.

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“…The shielding of engine sources, a key PAA effect representing much of the noise reduction potential of the HWB, could not be done adequately at that time with prediction methods. A detailed shielding experiment [24] albeit with a simplified point noise source [25] and no flow effect was used to supply the noise assessment with the effect of shielding. Within the constraints of this study the baseline HWB was assessed at a level of 22 dB cumulative below Stage 4 with aft radiated noise from the jet and fan exit as the components clearly representing the potential for additional noise reduction.…”

Section: Framework 21 Previous Studiesmentioning

confidence: 99%

Hybrid Wing Body Aircraft System Noise Assessment with Propulsion Airframe Aeroacoustic Experiments

Thomas

Burley

Olson

2012

International Journal of Aeroacoustics

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A system noise assessment of a hybrid wing body configuration was performed using NASA's best available aircraft models, engine model, and system noise assessment method. A propulsion airframe aeroacoustic effects experimental database for key noise sources and interaction effects was used to provide data directly in the noise assessment where prediction methods are inadequate. NASA engine and aircraft system models were created to define the hybrid wing body aircraft concept as a twin engine aircraft with a 7500 nautical mile mission. The engines were modeled as existing technology high bypass ratio turbofans. The baseline hybrid wing body aircraft was assessed at 22 dB cumulative below the FAA Stage 4 certification level. To determine the potential for noise reduction with relatively near term technologies, seven other configurations were assessed beginning with moving the engines two fan nozzle diameters upstream of the trailing edge and then adding technologies for reduction of the highest noise sources. Aft radiated noise was expected to be the most challenging to reduce and, therefore, the experimental database focused on jet nozzle and pylon configurations that could reduce jet noise through a combination of source reduction and shielding effectiveness. The best configuration for reduction of jet noise used state-ofthe-art technology chevrons with a pylon above the engine in the crown position. This configuration resulted in jet source noise reduction, favorable azimuthal directivity, and noise source relocation upstream where it is more effectively shielded by the limited airframe surface, and additional fan noise attenuation from acoustic liner on the crown pylon internal surfaces. Vertical and elevon surfaces were also assessed to add shielding area. The elevon deflection above the trailing edge showed some small additional noise reduction whereas vertical surfaces resulted in a slight noise increase. With the effects of the configurations from the database included, the best available noise reduction was 40 dB cumulative. Projected effects from additional technologies were assessed for an advanced noise reduction configuration including landing gear fairings and advanced pylon and chevron nozzles.

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Noise Scattering by the Blended Wing Body Airplane: Measurements and Prediction

Cited by 13 publications

References 10 publications

The U.S Air Force Next-Generation Air-Refueling System: a Resurgence of the Blended wing Body?

The U.S Air Force Next-Generation Air-Refueling System: a Resurgence of the Blended wing Body?

Hybrid Wing Body Aircraft Acoustic Test Preparations and Facility Upgrades

Hybrid Wing Body Aircraft System Noise Assessment with Propulsion Airframe Aeroacoustic Experiments

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