Influence of the Gap Flow of Axial Vehicle Cooling Fans on Radiated Narrowband and Broadband Noise

Becher, Marcus; Krusche, Roman; Tautz, Matthias; Mauß, Michael; Springer, Nils; Krömer, Florian; Becker, Stefan

doi:10.3813/aaa.919326

Cited by 7 publications

(3 citation statements)

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“…4b) need to be smaller than the tip gap clearance if the fan is operated above the micro-perforated sheet. The tip gap has significant influence on both the efficiency of the fan and its aeroacoustic behavior [40,41]. First of all, the efficiency is affected because a larger tip gap leads to increased blind flow affecting the pressure rise of the fan unfavorably.…”

Section: Inlet Test Chamber and Mpa Designmentioning

confidence: 99%

Design of an in-duct micro-perforated panel absorber for axial fan noise attenuation

2021

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The reduction of fan noise in ducts is a challenging task for acoustic engineers. Usually, the confined space where an absorber can be integrated is small. In addition, one has to consider the influence of the absorber on the flow field and the attenuation of noise should be as great as possible. In this contribution, we investigate the application of a micro-perforated absorber (MPA) in the direct vicinity of a low-pressure axial fan operating at low Mach number conditions. The micro-perforated plates (MPP) are modeled using the Johnson–Champoux–Allard–Lafarge (JCAL) model for porous materials. The entire geometrical setup of duct, fan and MPA is then simulated with the Finite Element (FE) method; the pre-processing effort is reduced by using non-conforming grids to discretize the different regions. The influence of the cavity length and the positioning of the fan are analyzed. The results are then applied to the construction of a full-sized MPA duct component that takes the limited space into consideration. Simulation results and overall functionality are compared to experimental results obtained in an axial-fan test rig. The Finite Element framework proved to be robust in predicting overall sound pressure level reduction in the higher volume flow rates. It is also shown that the MPP increases sound reduction in the low-frequency regime and at two resonant frequencies of the MPA setup. However, its main benefit lies in maintaining the efficiency of the fan. The location of the fan downstream or within the MPA has a significant effect on both the simulated and measured sound reduction.

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Section: Inlet Test Chamber and Mpa Designmentioning

confidence: 99%

Design of an in-duct micro-perforated panel absorber for axial fan noise attenuation

2021

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“…The aeroacoustic characteristics of cooling fans are determined by their aerodynamics, such as flow separation, secondary flow and other special flow structures. A large number of studies have been performed on aerodynamic characteristics [3][4][5][6][7][8][9] and aeroacoustic characteristics [10][11][12][13][14][15][16]. For example, Nashimoto et al [3] used phase-averaged PIV measurement and found that the separation and reattachment of the flow occurred on the suction surface at the leading edge of the blade.…”

Section: Introductionmentioning

confidence: 99%

“…For example, Nashimoto et al [3] used phase-averaged PIV measurement and found that the separation and reattachment of the flow occurred on the suction surface at the leading edge of the blade. Marcus et al [4] found that the clearance flow flows out of the clearance and then towards the blade, resulting in strong pressure fluctuations at the tip of the blade. Bo et al [5] found that there is leakage flow in the tip clearance and high-velocity region on the suction side near the blade tip.…”

Section: Introductionmentioning

confidence: 99%

Numerical Investigation on the Aerodynamic and Aeroacoustic Characteristics in New Energy Vehicle Cooling Fan with Shroud

Huang,

Xu,

Wang

et al. 2024

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The cooling fan is one of the important noise sources for new energy vehicles, and the research on its aerodynamic and aeroacoustic characteristics is of great help to improve the noise, vibration and harshness performance of new energy vehicles. However, most of these studies focus on the impeller, and little consideration has been given to the study of the shroud. Based on the coupling calculation method of large eddy simulation and the Ffowcs-Williams and Hawkings acoustics model, the aerodynamic and aeroacoustic characteristics in a cooling fan with the shroud are investigated at flow rates from 0.623 kg/s to 1.019 kg/s (where 0.865 kg/s is the flow rate corresponding to the best efficiency point). The accuracy of numerical simulation results is verified by the grid independence verification and the comparison of experimental data. Research shows that several large-scale vortex structures are observed in the clearance between the impeller and the shroud. The maximum peak-to-peak values of pressure fluctuation at different flow rates occur in the intermediate section or outlet section of the shroud. Although the shroud contributes relatively less to the far field noise, its different distribution may change the position of the maximum sound pressure level. The dominant frequency of pressure fluctuation equals the blade passage frequency (BPF) and the maximum SPL is around the BPF, both of which are independent of flow rates. The maximum SPL and the amplitude of the dominant frequency decrease as the flow rate increases.

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Influence of a micro-perforated duct absorber on sound emission and performance of axial fans

2021

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Influence of the Gap Flow of Axial Vehicle Cooling Fans on Radiated Narrowband and Broadband Noise

Cited by 7 publications

References 0 publications

Design of an in-duct micro-perforated panel absorber for axial fan noise attenuation

Design of an in-duct micro-perforated panel absorber for axial fan noise attenuation

Numerical Investigation on the Aerodynamic and Aeroacoustic Characteristics in New Energy Vehicle Cooling Fan with Shroud

Influence of a micro-perforated duct absorber on sound emission and performance of axial fans

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