Influence of blade skew on axial fan component noise

Herold, Gert; Zenger, Florian; Sarradj, Ennes

doi:10.1177/1475472x17718740

Cited by 26 publications

(19 citation statements)

References 35 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In a second step, the DAMAS beamforming algorithm (DAMAS stands for deconvolution approach for the mapping of acoustic sources) [54] with 100 iterations was applied to the CSM. This algorithm was chosen due to its good overall performance and its good reconstruction results for sources close to each other (especially at low frequencies [25,41,55]), which is important when analyzing airfoil leading-edge noise [2]. However, the disadvantage of this algorithm when compared to other common methods is the relatively high computational cost.…”

Section: Acoustic Measurements and Data Processingmentioning

confidence: 99%

“…However, leading-edge treatment approaches to reduce turbulence interaction noise also exist for axial fans, including leading-edge serrations [31][32][33][34][35][36] and porous materials [37][38][39]. In addition, modifications of the shape of the blades in the form of sweeping or skewing are known as effective means for noise reduction [3,[40][41][42][43][44].…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Permeable Leading Edges for Airfoil and Fan Noise Reduction in Disturbed Inflow

Ocker

Geyer

Czwielong³

et al. 2021

AIAA Journal

View full text Add to dashboard Cite

A detailed experimental study on the aerodynamic performance and noise emission of airfoils and fan blades with permeable leading edges under disturbed inflow conditions was performed. The airfoils and fan blades with permeable leading edges were made of an aluminum alloy using a powder bed fusion-based additive manufacturing process. In a first step, a wind-tunnel study was carried out. This consisted of detailed aerodynamic and aeroacoustic measurements on 16 airfoils with different permeable leading-edge designs that were performed for various flow speeds and geometric angles of attack. Based on the results from that study, unskewed fan blades with four different permeable leading-edge designs were manufactured in a second step. With the aim of reducing turbulence interaction noise of axial fans, the fans were examined with regard to their aerodynamic and acoustic properties under grid-generated turbulent inflow conditions. In a third step, a possible transfer of the observed noise emission from airfoils with permeable leading edge to that of fan blades was investigated. It was found that a notable broadband noise reduction can be transferred from airfoil applications to the sound spectra of axial fans. At the same time, the porous modifications can reduce the aerodynamic performance, and hence the fan efficiency.

show abstract

Section: Acoustic Measurements and Data Processingmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Permeable Leading Edges for Airfoil and Fan Noise Reduction in Disturbed Inflow

Ocker

Geyer

Czwielong³

et al. 2021

AIAA Journal

View full text Add to dashboard Cite

show abstract

“…Besides some other methods, the authors propose the following metric, defined along a periodic dimension γ with period P , shown in Eq. (8).…”

Section: Periodicitymentioning

confidence: 99%

A fuzzy clustering method for periodic data, applied for processing turbomachinery beamforming maps

Tóth

Vad

2018

Journal of Sound and Vibration

View full text Add to dashboard Cite

In the present paper, the fuzzy c-means method is extended, and an algorithm is proposed for fuzzy clustering of data lying in a feature space of arbitrary dimensions, with one of them being periodic. To aid in determining the optimal number of clusters, the Xie-Beni validity index is extended, to account for the periodicity. Furthermore, the relative weights of the dimensions in the calculation of distances are investigated. The method is incorporated into a procedure for processing turbomachinery beamforming maps. Thus, an objective, robust way of identifying the sound sources being present in such machines is obtained. These properties are ensured by selecting the required parameters through parameter studies. Presented through a case study, the method is used to determine the most significant sound source mechanisms in an axial fan.

show abstract

“…For instance, in the optimization of a swept benchmark fan carried out by Bamberger & Carolus [9] it was not clear whether the noise reduction was due to sweep or to the reduction of secondary flows. The influence of the operating conditions of the fan on the possibility of reducing noise by means of sweep is highlighted in [10], [11] and [12]. Herold et al [10] also pointed out that vortex shedding from the trailing-edge of a blade is significantly dependent on the component of the mean flow speed perpendicular to the edge.…”

Section: Introductionmentioning

confidence: 99%

Analytical model of the source and radiation of sound from the trailing edge of a swept airfoil

Grasso

Roger

Moreau

2021

Journal of Sound and Vibration

View full text Add to dashboard Cite

Highly-swept blades are used in automotive cooling systems, in the fans of modern ultra-high by-pass ratio engines and in counter-rotating open rotors, in part in order to reduce noise emission. The present work investigates the effect of sweep on the free-field noise emission from the trailing edge of an isolated airfoil analytically, as a first step towards a more complete approach dedicated to rotating blades. Firstly, Amiet-Schwarzschild's technique is extended to the case of a swept airfoil in order to assess the effect of sweep on the sound directivity both by a single three-dimensional gust and by the combined effect of all gusts at a given frequency. It is found that sweep produces a non-symmetric directivity pattern, similar to the effect of a skewed gust. Sweep also affects the wavenumber distribution of the wall-pressure fluctuations beneath a turbulent boundary layer. This effect is studied by means of a generalised Corcos' model, which allows distributing energy in the chordwise and spanwise wavenumber ranges independently. The role of the spanwise-wavenumber distribution of wall-pressure power spectral density in amplifying the radiated noise is investigated and shown to have a limited impact.

show abstract

Influence of blade skew on axial fan component noise

Cited by 26 publications

References 35 publications

Permeable Leading Edges for Airfoil and Fan Noise Reduction in Disturbed Inflow

Permeable Leading Edges for Airfoil and Fan Noise Reduction in Disturbed Inflow

A fuzzy clustering method for periodic data, applied for processing turbomachinery beamforming maps

Analytical model of the source and radiation of sound from the trailing edge of a swept airfoil

Contact Info

Product

Resources

About