Reduction of the tonal noise annoyance of axial flow fans by means of optimal blade spacing

Cattanei, Andrea; Ghio, Riccardo; Bongiovì, Alessandro

doi:10.1016/j.apacoust.2006.07.012

Cited by 42 publications

(18 citation statements)

References 9 publications

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“…Aerodynamic and acoustic optimization of MAV rotors has been previously addressed for instance by Ormsbee and Woan 5 on a vortex line theory approach or by Gur and Rosen 6 but only tonal noise was considered. Noise reduction techniques were proposed, yielding promising conclusions, such as an unequal blade spacing to reduce tonal noise 7 or a boundary layer trip to remove the broadband noise. 8 This contribution presents a general methodology for reducing the noise of MAV rotors while preserving or even increasing the endurance.…”

Section: Introductionmentioning

confidence: 99%

A design methodology for quiet and long endurance MAV rotors

Serré

Fournier

Moschetta

2019

International Journal of Micro Air Vehicles

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Over the last 10 years, the use of micro air vehicles has rapidly covered a broad range of civilian and military applications. While most missions require optimizing the endurance, a growing number of applications also require acoustic covertness. For rotorcraft micro air vehicles, combining endurance and covertness heavily relies on the capability to design new propulsion systems. The present paper aims at describing a complete methodology for designing quiet and efficient micro air vehicle rotors, ranging from preliminary aerodynamic prediction to aeroacoustic optimization to experimental validation. The present approach is suitable for engineering purposes and can be applied to any multirotor micro air vehicle. A fast-response and reliable aerodynamic design method based on the blade-element momentum theory has been used and coupled with an extended acoustic model based on the Ffowcs Williams and Hawkings equation as well as analytical formulations for broadband noise. The aerodynamic and acoustic solvers have been coupled within an optimization tool. Key design parameters include the number of blades, twist and chord distribution along the blade, as well as the choice of an optimal airfoil. An experimental test bench suitable for non-anechoic environment has been developed in order to assess the benefit of the new rotor designs. Optimal rotors can maintain high aerodynamic efficiency and low acoustic signature with noise reductions in the order of 10 dB(A).

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Section: Introductionmentioning

confidence: 99%

A design methodology for quiet and long endurance MAV rotors

Serré

Fournier

Moschetta

2019

International Journal of Micro Air Vehicles

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“…Then, an accurate aerodynamic study has to be carried out during the design phase, which usually results in non-radially stacked blades profiles [9]. Particular solutions such as uneven circumferential blades spacing [17] and rotating shroud [18] are typically used to modify and/or decrease the radiated SPL spectrum. Blade numbers and rotor-stator axial gap are also important [11,18].…”

Section: B Installation and Operation Of A Fan Versus Noise Emissionmentioning

confidence: 99%

Aerodynamic noise from cooling and HVAC systems features important to land vehicles in urban traffic conditions

Canepa

Cattanei

Zecchin

2013

2013 International Conference on Connected Vehicles and Expo (ICCVE)

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Abstract-The present paper deals with the aerodynamic noise generated by cooling and HVAC systems employed in land vehicles. After a brief description of the physical origin of aerodynamic noise, the features important to system engineers dealing with fans installation and operation are considered. First, the main scaling laws useful to estimate the sound level spectrum are reported. Then, the main characteristics of the sound pressure level spectrum are related to the typical aerodynamic generating mechanisms and to the quality of the perceived sound, and some guidelines for noise reduction are listed. Finally, a method for the employ of results obtainable from laboratory tests is proposed which aims to identify the origin of annoying fluctuations in the received noise.

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“…This method is applied by Duncan and Dawson 5 to axial flow machines, and they obtained a large reduction in discrete noise through a suitable choice of blade and vane numbers. Cattanei et al 6 present a method for the reduction of tonal nose from axial flow rotors by irregular spacing of blades. A local convexity-preserving structure at leading edge based on Bezier function method has been proposed by Zhou and Li,7 which is beneficial for the noise reduction without decreasing the performance of axial fans.…”

Section: Introductionmentioning

confidence: 99%

Numerical simulation and experimental research on the aerodynamic performance of large marine axial flow fan with a perforated blade

Yang

Wen

et al. 2017

Journal of Low Frequency Noise, Vibration and Active Control

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In this study, some of the optimal parameters for a new-style marine axial flow fan are defined by using numerical simulation and experimental tests with a large marine axial flow fan, based on the analysis of the blade perforation’s influences on its internal flow field and aerodynamic noise characteristics. Test result shows that the noise reduction for the axial flow fan with perforated blade is about 3 dB when the blade perforation diameter D is 10 mm and its deflection angle α is 45°. The results of the study show that there is an inhibitory effect on the discrete noise of axial flow fan with perforated blade on the tip area, and its total noise level emerged as the fluctuated distribution characteristics with the increase in the perforation diameter D and reduced along with the increase in the deflection of perforation angle α, at the same time varied as a linear characteristics, which can be reasonably explained by the acoustic interference theory. The results of the study have also further confirmed that the improvement of the flow of axial flow fan with perforated blade helps to reduce the pressure pulsation amplitude caused by the turbulence of the blade surface boundary layer, thereby suppressing the back-flow and vortex from the pressure surface to the suction surface efficiently. It is indicated that the improved vortex shedding phenomenon at the blade trailing edge after perforation on the area of blade tip is the main reason for the aerodynamic noise reduction of axial flow fan.

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Reduction of the tonal noise annoyance of axial flow fans by means of optimal blade spacing

Cited by 42 publications

References 9 publications

A design methodology for quiet and long endurance MAV rotors

A design methodology for quiet and long endurance MAV rotors

Aerodynamic noise from cooling and HVAC systems features important to land vehicles in urban traffic conditions

Numerical simulation and experimental research on the aerodynamic performance of large marine axial flow fan with a perforated blade

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