Numerical calculation of centrifugal fan noise

2006 ◽  
Vol 220 (8) ◽  
pp. 1167-1177 ◽  
Author(s):  
Q Liu ◽  
D Qi ◽  
Y Mao
Keyword(s):  
Numerical Study ◽  
Three Dimensional ◽  
Aerodynamic Noise ◽  
Noise Generation ◽  
Centrifugal Fan ◽  
Fan Noise ◽  
Sound Sources ◽  
Aerodynamic Sound ◽  
Frequency Level ◽  
Sound Levels

A numerical study on the aerodynamic noise generation of an industrial centrifugal fan with forward swept blades is carried out. Three-dimensional numerical simulations of the complete unsteady flowfield in the whole impeller — volute configuration are performed to obtain the aerodynamic sound sources. Then, aerodynamic sound is calculated using the Lowson equation and compared with the measurements. Moreover, the fan is modified for noise reduction by increasing the distance between the impeller tip and the volute tongue and sloping the volute tongue. The sound levels of the modified fan are lower than those of the original one over almost the entire range of frequencies analysed. The blade passing frequency level of the modified fan is decreased by about 15 dB at the design point. The method described and applied in this work provides a good qualitative prediction of the noise generation when designing a new fan, thus facilitating the choice of the lowest noise fan from several feasible alternatives.

Prediction of the Aerodynamic Noise Generated by a Centrifugal Fan: Numerical Results and Experimental Validation

2006 ◽  
Author(s):  
Rafael Ballesteros-Tajadura ◽  
Sandra Velarde-Sua´rez ◽  
Juan Pablo Hurtado-Cruz ◽  
Bruno Pereiras-Garci´a
Keyword(s):  
Three Dimensional ◽  
Prediction Method ◽  
Numerical Results ◽  
Experimental Results ◽  
Aerodynamic Noise ◽  
Centrifugal Fan ◽  
Fan Noise ◽  
Unsteady Forces ◽  
Model Extension ◽  
Centrifugal Fans

Centrifugal fans are widely used in several applications and, in some cases, the noise generated by these machines has become a serious problem. Usually, the centrifugal fan noise is dominated by tones at the blade passage frequency and its higher harmonics. This is a consequence of the strong interaction between the flow discharged from the impeller and the volute tongue. The purpose of this study is to develop a prediction method for the noise generated by a centrifugal fan. A three-dimensional numerical simulation of the complete unsteady flow on the whole impeller-volute configuration has been carried out using the computational fluid dynamics code FLUENT®. The unsteady forces applied by the fan blades to the fluid are obtained from the data provided by the simulation. The Ffowcs Williams and Hawkings model extension of Lighthill’s analogy predicts the aerodynamic noise generated by the centrifugal fan from these unsteady forces. Also, the noise generated by the fan has been measured experimentally, and the experimental results have been compared to the numerical results in order to validate the aerodynamic noise prediction methodology. A good agreement has been found between the numerical and the experimental results.

Numerical Prediction of the Aerodynamic Tonal Noise in a Centrifugal Fan

2002 ◽  
Author(s):  
Sandra Velarde-Sua´rez ◽  
Rafael Ballesteros-Tajadura ◽  
Carlos Santolaria-Morros ◽  
Joaqui´n Ferna´ndez-Francos
Keyword(s):  
Numerical Simulation ◽  
Unsteady Flow ◽  
Numerical Study ◽  
Three Dimensional ◽  
Numerical Results ◽  
Experimental Investigations ◽  
Noise Generation ◽  
Centrifugal Fan ◽  
Tonal Noise ◽  
Interaction Phenomena

In this work, a numerical study about the aerodynamic tonal noise generation in an industrial centrifugal fan with backward curved blades has been carried out. A three-dimensional numerical simulation of the complete unsteady flow on the whole impeller-volute configuration has been performed. Special attention has been focused on the impeller-volute interaction phenomena, analysing the influence of the distance between the impeller and the volute tongue. The numerical results have been contrasted using previous experimental investigations carried out in the same machine.

Experimental and Numerical Investigation of the Aerodynamic Noise Radiated From a Centrifugal Blower

2015 ◽  
Author(s):  
Jiandong Chen ◽  
Beibei Sun ◽  
Jianrun Zhang ◽  
Fei Xue ◽  
Xin Liu
Keyword(s):  
Three Dimensional ◽  
Prediction Method ◽  
Aerodynamic Noise ◽  
Centrifugal Fan ◽  
Centrifugal Blower ◽  
Fan Noise ◽  
Large Eddy Simulation Model ◽  
Scattering Effect ◽  
Eddy Simulation ◽  
Numerical Result

Centrifugal blowers are widely used as garden machines, however, the aerodynamic noise generated by these machines cause serious problems. Although many researches focus on the generation mechanism and prediction method of centrifugal fan noise, most of these researches analysis the simplified centrifugal fan models and ignore the diffraction and scattering effect. In this paper, both experimental and numerical methods are carried out to analysis and measure the aerodynamic noise of the centrifugal blower. In order to calculate the flow field, a CFD (Computational Fluid Dynamics) numerical model is established, and the LES (Large Eddy Simulation) model is used to solve the three-dimensional unsteady flow, while the FW-H (Ffows Williams-Hawkings) model is used to calculate the acoustic source. To consider the diffraction and scattering effect, a BEM method is used to predict the sound radiated from the blower. A parallel experiment is carried out to measure the aerodynamic noise in a semi-anechoic room, and the numerical result shows a good agreement with the experiment result. The effect of outlet and inlet ducts on the sound radiation of the centrifugal blower is also investigated in this paper.

Numerical investigations on the effect of volute casing treatment for performance augmentation in a centrifugal fan

2021 ◽  
pp. 095440622110341
Author(s):  
Manjunath L Nilugal ◽  
K Vasudeva Karanth ◽  
Madhwesh N
Keyword(s):  
Total Pressure ◽  
Static Pressure ◽  
Numerical Study ◽  
Pressure Coefficient ◽  
Three Dimensional ◽  
Pressure Rise ◽  
Centrifugal Fan ◽  
Casing Treatment ◽  
Sliding Mesh ◽  
Optimum Configuration

This article presents the effect of volute chamfering on the performance of a forward swept centrifugal fan. The numerical analysis is performed to obtain the performance parameters such as static pressure rise coefficient and total pressure coefficient for various flow coefficients. The chamfer ratio for the volute is optimized parametrically by providing a chamfer on either side of the volute. The influence of the chamfer ratio on the three dimensional flow domain was investigated numerically. The simulation is carried out using Re-Normalisation Group (RNG) k-[Formula: see text] turbulence model. The transient simulation of the fan system is done using standard sliding mesh method available in Fluent. It is found from the analysis that, configuration with chamfer ratio of 4.4 is found be the optimum configuration in terms of better performance characteristics. On an average, this optimum configuration provides improvement of about 6.3% in static pressure rise coefficient when compared to the base model. This optimized chamfer configuration also gives a higher total pressure coefficient of about 3% validating the augmentation in static pressure rise coefficient with respect to the base model. Hence, this numerical study establishes the effectiveness of optimally providing volute chamfer on the overall performance improvement of forward bladed centrifugal fan.

Numerical Study on Air-Reed Instruments With LES

2011 ◽  
Author(s):  
Kin’ya Takahashi ◽  
Masataka Miyamoto ◽  
Yasunori Ito ◽  
Toshiya Takami ◽  
Taizo Kobayashi ◽  
...  
Keyword(s):  
Numerical Study ◽  
Sound Field ◽  
Acoustic Analogy ◽  
Empirical Theory ◽  
Sound Sources ◽  
Aerodynamic Sound ◽  
Eddy Simulation ◽  
Large Eddy ◽  
Semi Empirical ◽  
2D And 3D

The acoustic mechanisms of 2D and 3D edge tones and a 2D small air-reed instrument have been studied numerically with compressible Large Eddy Simulation (LES). Sound frequencies of the 2D and 3D edge tones obtained numerically change with the jet velocity well following Brown’s semi-empirical equation, while that of the 2D air-reed instrument behaves in a different manner and obeys the semi-empirical theory, so called Cremer-Ising-Coltman theory. We have also calculated aerodynamic sound sources for the 2D edge tone and the 2D air-reed instrument relying on Ligthhill’s acoustic analogy and have discussed similarities and differences between them. The sound source of the air-reed instrument is more localized around the open mouth compared with that of the edge tone due to the effect of the strong sound field excited in the resonator.

Discrete Frequency Noise Generation From an Axial Flow Fan Blade Row

1970 ◽  
Vol 92 (1) ◽  
pp. 37-43 ◽  
Author(s):  
Ramani Mani
Keyword(s):  
Three Dimensional ◽  
Axial Flow ◽  
Acoustic Energy ◽  
Frequency Noise ◽  
Noise Generation ◽  
Two Dimensional ◽  
Axial Flow Fan ◽  
Fan Noise ◽  
Blade Row ◽  
Fan Blade

An analysis is presented which treats the noise generation from an axial flow fan row by given forces including the effects of a moving medium. The linearization of Euler’s equations to yield tractable problems for fan noise is discussed. The three-dimensional problem is decomposed into several two-dimensional problems. Finally, full details are given of a two-dimensional analysis to predict the amounts of acoustic energy, at the blade passing frequency and its harmonics, radiated up and downstream of a blade row due to its interaction with a neighboring row.

A Numerical Study of the Blade Passing Frequency Noise of a Centrifugal Fan

2012 ◽  
Author(s):  
Jian-Cheng Cai ◽  
Da-Tong Qi ◽  
Yong-Hai Zhang
Keyword(s):  
Pressure Fluctuation ◽  
Sound Radiation ◽  
Aerodynamic Noise ◽  
Sound Power ◽  
Centrifugal Fan ◽  
Structural Noise ◽  
Tonal Noise ◽  
Fan Noise ◽  
Blade Passing Frequency ◽  
Dipole Sources

Tonal noise constitutes the major part of the overall fan noise, especially the blade passing frequency (BPF) noise which is generally the most dominant component. This paper studies the BPF tonal noise of a centrifugal fan, including the blade noise, casing aerodynamic noise, and casing structural noise caused by the flow-induced casing vibration. Firstly, generation mechanism and propagation process of fan noise were discussed and the measured spectra of fan noise and casing vibration were presented. Secondly, a fully 3-D transient simulation of the internal flow field of the centrifugal fan was carried out by the computational fluid dynamics (CFD) approach. The results revealed that the flow interactions between the impeller and the volute casing caused periodic pressure fluctuations on the solid walls of the impeller and casing. This pressure fluctuation induces aerodynamic noise radiation as dipole sources, as well as structural vibration as force excitations. Thirdly, using the acoustic analogy theory, the aeroacoustic dipole sources on the casing and blade surface were extracted. The BPF casing and blade aerodynamic sound radiation were solved by the boundary element method (BEM) taking into account the scattering effect of the casing structure. Finally, the casing structural noise was studied. The casing forced vibration and sound radiation under the excitation of BPF pressure fluctuation were calculated by finite element method (FEM) and BEM, respectively. The result indicates that at the studied flow rate, the sound power levels of the casing aerodynamic noise, blade aerodynamic noise and casing structural noise are 103 dB, 91 dB and 79 dB with the reference sound power of 1×10−12 W, respectively.

Optimization of Low-Noise and Large Air Volume Blower Based on Load Characteristic

2015 ◽  
Vol 656-657 ◽  
pp. 700-705
Author(s):  
Jian Dong Chen ◽  
Bei Bei Sun
Keyword(s):  
Flow Rate ◽  
Low Noise ◽  
Aerodynamic Noise ◽  
Strong Wind ◽  
Centrifugal Fan ◽  
Fan Noise ◽  
Load Characteristic ◽  
Air Volume ◽  
Actual Working ◽  
Working Point

The blower is a kind of garden machinery, which blows strong wind to clean up leaves by a centrifugal fan, but it causes a loud aerodynamic noise. To compromise the contradiction between large air flow rate and low fan noise, some optimizations are proposed to reduce fan noise without lowering its air volume. In this paper, a CFD numerical model to compute airflow field of blower is established, where the centrifugal fan is simulated by the MRF model, and theturbulent model is selected. By smoothing the transition section, improving the volute tongue and optimizing the shape and optimizing number of fan blade, the blower work performance is increased obviously. In order to find out the actual working point, both the fan and motor load characteristic curves are drawn out. The simulation results show that, at the actual working point, the speed of the centrifugal fan is reduced, while the flow rate of blower is raised up. The optimizations are applied to the blower, and the experiment of the improved blower shows the flow rate is increased 5%, and the noise is reduced 2dB.

Calculations of three-dimensional viscous flow in a multiblade centrifugal fan by modelling blade forces

2003 ◽  
Vol 217 (3) ◽  
pp. 287-297 ◽  
Author(s):  
S-J Seo ◽  
K-Y Kim ◽  
S-H Kang
Keyword(s):  
Mathematical Model ◽  
Turbulent Flows ◽  
Numerical Study ◽  
Three Dimensional ◽  
Navier Stokes ◽  
Centrifugal Fan ◽  
Complex Flows ◽  
Flow Through ◽  
Volume Method ◽  
The Mathematical Model

A numerical study is presented for Reynolds-averaged Navier-Stokes analysis of three-dimensional turbulent flows in a multiblade centrifugal fan. Present work aims at development of a relatively simple analysis method for these complex flows. A mathematical model of impeller forces is obtained from the integral analysis of the flow through the impeller. A finite volume method for discretization of governing equations and a standard k-ɛ model as turbulence closure are employed. For the validation of the mathematical model, the computational results for velocity components, static pressure, and flow angles at the exit of the impeller were compared with experimental data. The comparisons show generally good agreement, especially at higher flow coefficients.

Numerical Assessment of 2D Aeroacoustic Simulations for Landing Gear

2018 ◽  
Author(s):  
Sultan I. Alqash ◽  
Kamran Behdinan
Keyword(s):  
Acoustic Field ◽  
Numerical Study ◽  
Near Field ◽  
Three Dimensional ◽  
Aerodynamic Noise ◽  
Design Stage ◽  
Acoustic Analogy ◽  
Ansys Fluent ◽  
2D Flow ◽  
Field Noise

Landing gears (LG) are primarily designed to support the entire loads of an aircraft during landing, taxiing, and taking off. From aerodynamic design prospective, many of the LG components are exposed to the air flow giving rise to what so-called aerodynamic noise. Numerical study of complex systems such as LG as a three-dimensional (3D) model is not only CPU and memory consuming, but also it is way beyond the demand of industries for quick estimate during the design stage [1–3]. To understand the underlying physics of the flow induced noise, a two-dimensional (2D) flow past a circular cylinder is simulated using ANSYS Fluent. Two different Reynolds numbers, Re = 150 and 90000 are examined. For low Re, two distinct numerical conditions relevant to steady and unsteady flow are simulated and compared to examine the effect of the time dependency on the acoustic field. At high Re, the acoustic field is computed using the built-in Ffowcs William and Hawkings (FW-H) acoustic analogy solver in Fluent. The results show the importance of including the unsteady state term to extract the flow data. The far-field noise prediction is found to be highly dependent on the location of the near-field data.

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