Annoyance to Noise Produced by a Distributed Electric Propulsion High-Lift System

Rizzi, Stephen A.; Palumbo, Daniel L.; Rathsam, Jonathan; Christian, Andrew; Rafaelof, Menachem

doi:10.2514/6.2017-4050

Cited by 29 publications

(32 citation statements)

References 11 publications

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“…To address this threat, emerging electric propulsion architectures have been promoted as a means to significantly reduce vehicle source noise through the removal of combustion engines and the utilization of distributed rotors. However, initial psychoacoustic tests performed by NASA suggested that listener annoyance may increase with the number of propellers on an aircraft in a statistically significant manner [41].…”

Section: Noise and Community Acceptancementioning

confidence: 99%

Scaling Constraints for Urban Air Mobility Operations: Air Traffic Control, Ground Infrastructure, and Noise

Vascik

Hansman

2018

2018 Aviation Technology, Integration, and Operations Conference

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The scalability of the current air traffic control system, the availability of aviation ground infrastructure, and the acceptability of aircraft noise to local communities have been identified as three key operational constraints that may limit the implementation or growth of Urban Air Mobility (UAM) systems. This paper identifies the primary mechanisms through which each constraint emerges to limit the number of UAM operations in an area (i.e. the scale of the service). Technical, ecosystem, or operational factors that influence each of the mechanisms are also identified. Interdependencies between the constraints are shown. Potential approaches to reduce constraint severity through adjustments to the mechanisms are introduced. Finally, an effort is made to characterize the severity of each operational constraint as a function of the density of UAM operations in a region of interest. To this end, a measure of severity is proposed for each constraint. This measure is used to notionally display how the severity of the constraint responds to UAM scaling, and to identify scenarios where efforts to relieve the constraint are most effective. The overall purpose of this paper is to provide an abstraction of the workings of the key UAM operational constraints so that researchers, developers, and practitioners may guide their efforts to mitigation pathways that are most likely to increase achievable UAM system scale. U 2 American Institute of Aeronautics and Astronautics perceive to degrade their quality of life and enjoyment of their property. Local governments may use zoning or building codes to limit or prohibit aviation infrastructure development or operations. Finally, congressional representatives may compel the FAA to change ATC procedures to reduce noise, as was the case in the Los Angeles Residential Helicopter Noise Relief Act of 2013 [4]. While community acceptance of UAM activities may be influenced by numerous factors including privacy, viewshed, pollution, safety, and equity, aircraft noise has dominated recent public discourse and action and represents a key constraint for UAM operations. However, the successful implementation of helicopter-based UAM operations in São Paulo, as well as the large private and charter helicopter operations in Moscow and Mumbai, indicate that local values and expectations significantly influence the actual severity of this constraint. U.S. and European communities may exhibit increased sensitivity to aircraft noise compared to other potential UAM markets.These three operating constraints are of keen interest to researchers, potential operators, and transportation planners as they dictate if a UAM system may serve a few hundred customers per day or tens of thousands of customers per day. The contribution of this research is significant because it will support the estimation of achievable UAM system scale based upon local factors and the ecosystem of the city in which it is implemented. Furthermore, this work may support the evaluation of how potential design and operating decisi...

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Section: Noise and Community Acceptancementioning

confidence: 99%

Scaling Constraints for Urban Air Mobility Operations: Air Traffic Control, Ground Infrastructure, and Noise

Vascik

Hansman

2018

2018 Aviation Technology, Integration, and Operations Conference

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“…In actuality, the phase controller will have to continuously compensate for environment interaction such as wind gusts, turbulence ingestion, etc. Rizzi et al 2 studied the effect of a motor control error for a spread frequency design. The derivation equivalently applies to modeling a phase error (a direct result of a change in RPM) and is used here.…”

Section: Ivc Phase Control Potential For Noise Reductionmentioning

confidence: 99%

“…Given the importance of the waveform, traditional A-weighting of the sound pressure spectrum may not be an appropriate metric to fully reflect human response. 2 To this end, the resulting noise model herein will be a time domain formulation. At this point, however, the most appropriate acoustic metrics for these vehicles are not yet established.…”

Section: Introductionmentioning

confidence: 99%

Tonal Noise Prediction of a Distributed Propulsion Unmanned Aerial Vehicle

Pascioni

Rizzi

2018

2018 AIAA/CEAS Aeroacoustics Conference

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Noise is expected to be a major barrier of unmanned aerial vehicles (UAVs) to public acceptance. A noise prediction scheme is introduced in this paper and applied to a specific vehicle configuration, namely, the Greased Lightning-10. Results herein will be used to demonstrate the feasibility of incorporating a noise constraint within the flight control system of a distributed electric propulsion vehicle by modifying commands for lownoise operation over sensitive areas, e.g., communities, schools, etc. Steady loading and thickness noise signatures of single propellers are computed using the Propeller Analysis System of the NASA Aircraft NOise Prediction Program. The individual signatures are then superposed at far field observers after applying corrections for spherical spreading and phase delays based on straight ray propagation. Two-propeller source fields are verified using analytical directivity patterns of monopoles. Notional effects of rotation rate, rotation direction, and relative propeller phase are given. Under ideal circumstances and equivalent RPM, random phasing, which occurs in most small UAVs, can produce up to 20 dB uncertainty in the tonal sound pressure level at a given ground observer. Additionally, directivity modification via relative propeller phase control is shown to have great potential as a noise reduction technique. This paper will focus on the forward flight mode but will also briefly discuss the vertical flight mode.

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“…Therefore, this paper also investigates whether Aures Tonality can improve the assessment of human response in relation to tonal content of contemporary aircraft. Thirdly, the noise signature of some future aircraft designs and engine developments, such as Ultra-High Bypass Ratio (BPR) turbofans [31], Counter Rotating Open Rotor (CROR) engines [23,30,32], or Distributed Electric Propulsion systems [33], will be likely to have a significant complex tonal content. For this reason, this paper discusses the limitations of current tonality assessment methods, and suggests potential improvements for appropriately assessing the subjective response to aircraft noise with significant complex tonal content.…”

Section: Introductionmentioning

confidence: 99%

On the assessment of subjective response to tonal content of contemporary aircraft noise

et al. 2019

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The Effective Perceived Noise Level (EPNL) is the primary metric used for assessing subjective response to aircraft noise. The EPNL comprises calculation of the Perceived Noise Level (in PNdB), and takes into account flyover duration and the presence of pure tones to arrive at an adjusted EPNL value. With the presence of a single significant tone, EPNL has been found to be reasonably effective for the assessment of aircraft noise annoyance. Several authors have, however, suggested that EPNL is not capable of quantifying the subjective response to aircraft noise that contains multiple complex tones. The noise source referred to as "Buzz-saw" noise is a typical example of complex tonal content in aircraft noise with an important effect on both cabin and community noise impact. This paper presents the results of a series of listening tests where a number of participants were exposed to samples of aircraft noise with six variants of aircraft engines, assumed representative of the contemporary twin engine aircraft fleet. On the basis of the findings of these listening tests, the Aures tonality method significantly outperforms the EPNL tone correction method when assessing the subjective response to aircraft noise during takeoff with the presence of multiple complex tones. The participants reported 'high pitch' as one of the least preferable aircraft noise characteristics, and consequently, the psychoacoustics metric Sharpness was found to be another important contributor to subjective response to the noise of two specific aircraft engine groups (out of the six considered). The limitations of Aures tonality are discussed, in particular for aircraft noise with both a series of complex tones spaced evenly across the frequency spectrum with relatively even sound levels and less subjectively dominant single frequency tones (compared to broadband noise). In line with these limitations, further work is proposed for more effective assessment of subjective response to aircraft noise containing significant tonal content in the form of numerous closely spaced or other complex tones.

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Annoyance to Noise Produced by a Distributed Electric Propulsion High-Lift System

Cited by 29 publications

References 11 publications

Scaling Constraints for Urban Air Mobility Operations: Air Traffic Control, Ground Infrastructure, and Noise

Scaling Constraints for Urban Air Mobility Operations: Air Traffic Control, Ground Infrastructure, and Noise

Tonal Noise Prediction of a Distributed Propulsion Unmanned Aerial Vehicle

On the assessment of subjective response to tonal content of contemporary aircraft noise

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