Quieter propeller with serrated trailing edge

Lee, Hsiao Mun; Lu, Zhenbo; Lim, Kian Meng; Xie, Jinlong; Lee, Heow Pueh

doi:10.1016/j.apacoust.2018.11.020

Cited by 33 publications

(9 citation statements)

References 14 publications

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“…A broadband noise reduction is observed for all the serrated models, up to a maximum of 8 dB. Lee et al [22] conducted experimental testing on rotors with flat-tip trailing-edge serration, that is, the sawtooth serration where the sharp tip is cut in order to become flat, and rectangular serrations. The flattip serrated propeller showed the highest broadband noise attenuation at 3000 rpm, corresponding to an overall noise reduction of 5.8 dBA.…”

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confidence: 99%

Aeroacoustic Investigation of a Propeller Operating at Low Reynolds Numbers

et al. 2022

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This paper presents an experimental investigation of a propeller operating at low Reynolds numbers and provides insights into the role of aerodynamic flow features on both propeller performances and noise generation. A propeller operating at a tip Reynolds number regime of 4.3 × 10 4 − 4.38 × 10 4 is tested in an anechoic wind tunnel at an advance ratio ranging from 0 to 0.6. Noise is measured by means of a microphone array, while aerodynamic forces are measured with load and torque cells. Oil-flow visualizations are used to show the flow patterns on the blade surface, whereas phase-locked stereoscopic particle image velocimetry (PIV) measurements are carried out to analyze the flow at 60% of the blade radius. The pressure field around the blade section has been computed from the PIV velocity data. Results reveal a complex flowfield with the appearance of a laminar separation bubble at the suction side of the blade. The separation bubble moves toward the leading edge and reduces in size as the advance ratio decreases. At an advance ratio equal to 0.6, the flowfield is characterized by a laminar separation without reattachment. This causes vortex shedding responsible for a high-frequency hump in the far-field noise spectra.

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confidence: 99%

Aeroacoustic Investigation of a Propeller Operating at Low Reynolds Numbers

et al. 2022

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“…Aerodynamic and acoustic investigations of multi-copter rotors with trailing edge serrations have been performed. The results suggested that the serrated rotor had a total sound pressure level attenuation of 0.9-1.6 dB [46,47]. The noise reduction effect through leading-edge serrations was studied on two-dimensional airfoils, and alleviated the total sound pressure level of 1.5 dB [48].…”

Section: Aeroacoustics and Transmission Loss Analysismentioning

confidence: 98%

Structural Design and Parameter Optimization of Bionic Exhaust Tailpipe of Tractors

et al. 2022

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The exhaust tailpipe of a certain type of tractor was improved from the perspective of bionics, and bionic triangular convex texture was added to the inner surface of the exhaust tailpipe. The bionic tailpipe was proposed to improve noise reduction performance without changing the overall size parameters of the prototype tailpipe. Acoustics simulation software was used to predict the aeroacoustics noise and transmission loss of the exhaust tailpipe. Bionic exhaust tailpipes with triangular textures of different numbers of circumferential columns, height, and top angles were analyzed to study the noise reduction performance. The results showed that the proposed bionic exhaust tailpipes with triangular convex textures reduced the total sound pressure level and improved the transmission loss of the prototype exhaust tailpipe. To increase the transmission loss, a genetic algorithms (GA) optimized back-propagation neural network (BP) was used to optimize the bionic triangular convex texture parameters. By studying the aerodynamic noise reduction mechanism of bionic tailpipes, the research suggested that a secondary vortex appeared near the bionic texture and reduced aerodynamic drag and aeroacoustics noise. In addition, the sound pressure level amplitude nephogram, velocity vector nephogram, and velocity amplitude nephogram of the exhaust tailpipes were analyzed to study the vibration noise reduction mechanism of the bionic tailpipes. Then, the noise reduction performance was experimentally evaluated. The experimental results of the bionics exhaust tailpipes with triangular convex textures were analyzed and compared to that of the prototype tailpipe. The results demonstrated that the bionic exhaust tailpipes were able to attenuate noise.

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“…The airfoil self-noise, which is created by the blade in an undisturbed inflow, is the second type. Self-noise in airfoils is further separated into two noise mechanisms: trailing edge and blade tip vortex noises [11,12].…”

Section: Introductionmentioning

confidence: 99%

Thrust Force for Drone Propeller with Normal and Serrated Trailing Edge

Bahrom

Manshoor²,

Zain³

et al. 2023

ARFMTS

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The drone becomes more recognized in the civilian sector; the drone's popularity becomes increases as time goes by. Nevertheless, despite the excitement of flying drones, several types of issues occur caused by the drone. In some circumstances, the aeroacoustics noise is a big concern, and quiet drone propellers would be more environmentally friendly to the surrounding area. Moreover, the noise from the drone can be a nuisance for the surrounding population and animals. Therefore, a solution needs to be proposed to reduce the sound level produced by the drone so that drone can be piloted in a surrounding area without breaking any noise level limit set by the government. Hence, the propeller's serrated trailing edge type is the proposed solution to this problem. The serrated trailing edge propeller can reduce several drone noise decibels based on past research. Thus, an investigation is conducted to study the thrust force between the normal propeller and the serrated propeller. The aerodynamic performance of the serrated propeller is analysed using computational fluid dynamic simulation and compared to that of the normal propeller. Ansys Fluent 2021 is used to solve the dependable RNG k-epsilon turbulence model. The thrust force, thrust coefficient, and lift coefficient operating on both propellers were all simulated. The results obtained by the transient approach for propellers have been validated by earlier experimental studies.

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Quieter propeller with serrated trailing edge

Cited by 33 publications

References 14 publications

Aeroacoustic Investigation of a Propeller Operating at Low Reynolds Numbers

Aeroacoustic Investigation of a Propeller Operating at Low Reynolds Numbers

Structural Design and Parameter Optimization of Bionic Exhaust Tailpipe of Tractors

Thrust Force for Drone Propeller with Normal and Serrated Trailing Edge

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