Effect of the uneven blade spacing on the noise annoyance of axial-flow fans and side channel blowers

Cattanei, Andrea; Zecchin, Fabio Mazzocut; Pasquali, Alessandro Di; Lazari, Andrea

doi:10.1016/j.apacoust.2021.107924

Cited by 11 publications

(4 citation statements)

References 47 publications

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“…Thus, the interval angle between front and rear blade is responsible for the improvement of the acoustic performance, leading to the pronounced peaks in a cycle, which is distinguished from those of the blade passing frequency harmonics. This finding is supported by the experimental study by Cattanei (2021) [41] in association with the aeroacoustics of a fan uneven blade.…”

Section: Discussionsupporting

confidence: 66%

“…While the higher broadband noise is observed at high frequency in the loop-type propeller with a noticeable increase in sharpness, an apparent reduction is observed in the prominence of the tonal peaks (i > 25 * NB) (Figure 7). This result was supported by an experimental study by Cattanei et al [41]. In addition, it is worth noting that the low-frequency modulation noise (<4 Hz), i.e., the source of the fluctuation strength, is normally caused by a slightly different rotational speed (<4 RPS) of the multiple propellers rather than the isolated propellers.…”

Section: Discussionsupporting

confidence: 65%

“…Interestingly, it is found that the broadband noise exceeding 6000 Hz of the four-blade propeller (#2) is noticeably higher than that of the loop-type propellers (#3 and #4) (Figure 12). This may be reasonably explained by the featured morphology of the loop-type propellers, which suppress the wingtip vortex, and hence the vortex-dominated flow interaction, in comparison to the four individual blades, whereas the broadband noise suppression cannot be achieved by the conventional uneven multiple blade structures, as reported in previous studies of the axial flow fans [39][40][41].…”

Section: Discussionsupporting

confidence: 52%

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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: Discussionsupporting

confidence: 66%

Section: Discussionsupporting

confidence: 65%

Section: Discussionsupporting

confidence: 52%

See 1 more Smart Citation

Integrated Evaluation of the Aeroacoustics and Psychoacoustics of a Single Propeller

Sun

Yonezawa

Shima

et al. 2023

IJERPH

View full text Add to dashboard Cite

show abstract

“…Peng Z et al [20] developed a theoretical model to quickly predict and control the tonal noise of an automotive cooling fan, which can be used to effectively and quickly predict and control the tonal noise at an early stage of the automotive cooling fan module design. Cattanei A. et al [21] further investigated the effect of unequally spaced leaves on sound quality.…”

Section: Introductionmentioning

confidence: 99%

Noise Reduction Design Method and Validation of Unequal-Pitch Blade Fan for Traction Motor

Li,

Yang,

et al. 2023

Processes

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The traction motor of trains is an essential component that generates the traction force, but it has a significant influence on the indoor and outdoor acoustic environment during the running condition. To enhance passenger comfort and bolster the environmental performance of trains, regulatory standards and specifications governing train noise have imposed elevated criteria on both tonal noise and the overall A-weighted sound pressure level emanating from traction motors. This paper proposes an aerodynamic noise optimization design method based on aerodynamic interference. The objective function of the optimization is defined as the blade-passing frequency (BPF) noise and the A-weighted overall sound pressure level of the traction motor fan. The simulated annealing algorithm is used to optimize the circumferential distribution of the blades. The optimized unevenly spaced blade configuration of the fan effectively reduces the BPF sound pressure level amplitude by 4.6 dBA and the overall A-weighted sound pressure level by 1.2 dBA. The calculation results agree well with the experimental results. The study reveals that unevenly spaced blades contribute to better noise reduction at lower rotational speeds. However, the effect diminishes at higher speeds. The relationship between noise reduction and blade count is nonlinear, suggesting an optimal count for specific speeds.

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Impact of geometric modifications of small axial fans on psychoacoustic metrics

Novaković,

Čurović,

Hočevar

et al. 2024

Applied Acoustics

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Effect of the uneven blade spacing on the noise annoyance of axial-flow fans and side channel blowers

Cited by 11 publications

References 47 publications

Integrated Evaluation of the Aeroacoustics and Psychoacoustics of a Single Propeller

Integrated Evaluation of the Aeroacoustics and Psychoacoustics of a Single Propeller

Noise Reduction Design Method and Validation of Unequal-Pitch Blade Fan for Traction Motor

Impact of geometric modifications of small axial fans on psychoacoustic metrics

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