Small aircraft propeller noise with ducted propeller

Oleson, R. Duane; Beach, West Palm; Patrick, Howard

doi:10.2514/6.1998-2284

Cited by 10 publications

(9 citation statements)

References 1 publication

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“…As the major sound source of rotorcrafts, the noise emission characteristics of propulsion systems, practically propellers, have been the main subject to be explored in many previous studies [10][11][12][13][14][15][16][17][18], for the purpose of reducing the propellers' aerodynamic noise, comprising tonal noise and broadband noise [19]. The broadband noise generally originates from three different sources: the noise caused by the formation and shedding of vortices around blades, the noise produced directly by the turbulent boundary layer interacting with the trailing edge of the blade, and the noise induced by the flow separation on the 2 of 23 airfoil surface.…”

Section: Introductionmentioning

confidence: 99%

“…Thus, it is important to investigate the various components in association with the tonal noise and broadband noise so as to quantify the noise characteristics of drone propellers. To suppress the noise generation in the overall sound pressure level (OASPL), which is broadly used to evaluate the intensity of noise samples, efforts on propeller design are usually made in applying bioinspired serration structures [10][11][12], add-in structures to control fluid fields [13,14,18], and advanced control methods [15,16]. Recently, we proposed a low-noise loop-type propeller that can generate lift forces with loops rather than conventional blades and achieved a significant reduction in the OASPL [17].…”

Section: Introductionmentioning

confidence: 99%

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Integrated Evaluation of the Aeroacoustics and Psychoacoustics of a Single Propeller

Sun

Yonezawa

Shima

et al. 2023

IJERPH

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Aeroacoustic noise in multiple rotor drones has been increasingly recognized as a crucial issue, while noise reduction is normally associated with a trade-off between aerodynamic performance and sound suppression as well as sound quality improvement. Here, we propose an integrated methodology to evaluate both aeroacoustics and psychoacoustics of a single propeller. For a loop-type propeller, an experimental investigation was conducted in association with its aerodynamic and acoustic characteristics via a hover stand test in an anechoic chamber; the psychoacoustic performance was then examined with psychoacoustic annoyance models to evaluate five psychoacoustic metrics comprising loudness, fluctuation strength, roughness, sharpness, and tonality. A comparison of the figure of merit (FM), the overall sound pressure level (OASPL) and psychoacoustic metrics was undertaken among a two-blade propeller, a four-blade propeller, the loop-type propeller, a wide chord loop-type propeller, and a DJI Phantom III propeller, indicating that the loop-type propeller enables a remarkable reduction in OASPL and a noticeable improvement in sound quality while achieving comparable aerodynamic performance. Furthermore, the psychoacoustic analysis demonstrates that the loop-type propeller can improve the psychological response to various noises in terms of the higher-level broadband and lower-level tonal noise components. It is thus verified that the integrated evaluation methodology of aeroacoustics and psychoacoustics can be a useful tool in the design of low-noise propellers in association with multirotor drones.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Integrated Evaluation of the Aeroacoustics and Psychoacoustics of a Single Propeller

Sun

Yonezawa

Shima

et al. 2023

IJERPH

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“…Instead, a combination of active and passive mitigation strategies and hearing protection gear (e.g., ear muffs/plugs) have been found to be most feasible. Among these are attempts to tweak propeller dimensions (Molland et al, 2014; Tinney and Sirohi, 2018), propeller geometry (Štorch et al, 2016; Demoret and Wisniewski, 2019), number of propeller blades (Metzger, 1995), or the use of additional propeller ducts (Oleson and Patrick, 1988) and Helmholtz-resonator-based metasurfaces (Zhao et al, 2017) to reduce the generated noise. In the active domain, active noise cancellation (ANC) techniques (Miljković, 2018; Leventhall and Wong, 1988) have been adopted using complex electronic hardware to counter the UAV’s propeller noise output.…”

Section: Introductionmentioning

confidence: 99%

Integration of acoustic compliance and noise mitigation in path planning for drones in human–robot collaborative environments

Adlakha

Liu

Chowdhury

et al. 2022

Journal of Vibration and Control

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This work presents a framework aimed at mitigating adverse effects of high-amplitude drone noise ranging from hearing loss to reduced productivity in human–robot collaborative environments by infusing acoustic awareness in a path planning algorithm without imposing any additional design layers or hardware to an operational drone. Following a detailed outline of the proposed approach, it is shown that a significant reduction of noise levels perceived by human workers at noise-sensitive locations is realized via a path planner which generates optimal paths ranging from quietest to shortest paths. The approach is then augmented with a path-correction mechanism which accounts for noise exposure duration to ensure the aforementioned optimal paths are compliant with a given industrial/environmental standard. The correction mechanism enforces an adjustment of subsets of the planned paths inside quiet zones designated around noise-sensitive locations. The presented concepts were verified using numerical simulations conducted for a 2-dimensional rasterized obstacle field followed by a statistical design of experiments. The proposed framework is highly versatile and integrable with widely used industrial path planners, rendering it a highly valuable tool for noisy collaborative workplaces.

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“…A ducted propeller is thus commonly referred to as a way of improving the propulsive efficiency of the UAV but also as a way of reducing noise emissions, 8,9 although recent work indicates a slight increment of noise when a hard wall duct, without lining, is introduced. 10 Sound propagation in a duct poses a complex problem.…”

Section: Introductionmentioning

confidence: 99%

“…For propellers, the noise consists both of tonal and broadband noise. 9,13 The different mechanisms that originate broadband noise are for example, the blade tip clearance, and the interaction of the wake generated by the fan blades with the duct boundary layer.…”

Section: Introductionmentioning

confidence: 99%

Experimental characterization of noise radiation from a ducted propeller of an unmanned aerial vehicle

Malgoezar

Vieira

Snellen

et al. 2019

International Journal of Aeroacoustics

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Ducted propellers are an interesting design choice for unmanned aerial vehicle (UAV) concepts due to a potential increase of the propeller efficiency. In such designs, it is commonly assumed that introducing the duct also results in an overall noise reduction. The objective of this work is to experimentally analyze and quantify noise of a ducted propeller suitable to be installed on a medium size UAV (wingspan 5-10 m). A microphone array is used for recording the noise levels at each microphone position and used collectively to localize noise sources with beamforming. Different types of noise sources are considered (an omni-directional source and a propeller). In addition, the effect of the presence of an incoming airflow is assessed. With no incoming airflow, it is found that the duct significantly modifies the noise radiation both in the frequency and the spatial domain. With an incoming airflow, the effect of the duct on the frequency content of the signal is almost eliminated. The fact that for this case the harmonics become lower results in a reduction of the received noise levels. Also the directivity changes. These insights are of importance in efforts towards modeling the effects of ducts for complex noise sources such as propellers.

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Small aircraft propeller noise with ducted propeller

Abstract: The purpose of this paper was to document the results of initial testing of various configurations of a ducted propeller apparatus.

Cited by 10 publications

References 1 publication

Integrated Evaluation of the Aeroacoustics and Psychoacoustics of a Single Propeller

Integrated Evaluation of the Aeroacoustics and Psychoacoustics of a Single Propeller

Integration of acoustic compliance and noise mitigation in path planning for drones in human–robot collaborative environments

Experimental characterization of noise radiation from a ducted propeller of an unmanned aerial vehicle

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