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.

Noise Prediction of a Centrifugal Fan: Numerical Results and Experimental Validation

2008 ◽  
Vol 130 (9) ◽  
Author(s):  
Rafael Ballesteros-Tajadura ◽  
Sandra Velarde-Suárez ◽  
Juan Pablo Hurtado-Cruz
Keyword(s):  
Three Dimensional ◽  
Cross Flow ◽  
Numerical Results ◽  
Experimental Results ◽  
Aerodynamic Noise ◽  
Navier Stokes ◽  
Noise Prediction ◽  
Centrifugal Fan ◽  
Unsteady Forces ◽  
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. The centrifugal fan noise is frequently dominated by tones at the blade passing frequency as a consequence of the strong interaction between the flow discharged from the impeller and the volute tongue. In this study, a previously published aeroacoustic prediction methodology (Cho, Y., and Moon, Y.J., 2003, “Discrete Noise Prediction of Variable Pitch Cross-Flow Fans by Unsteady Navier-Stokes Computations,” ASME J. Fluids Eng., 125, pp. 543–550) has been extended to three-dimensional turbulent flow in order to predict 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 has been used to predict 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. Reasonable agreement has been found between the numerical and the experimental results.

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 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.

Numerical and Experimental Evaluation of Turbulent Flow in Volute

2003 ◽  
Author(s):  
Akitomo Igarashi ◽  
Kazuyuki Toda ◽  
Makoto Yamamoto ◽  
Toshimichi Sakai
Keyword(s):  
Numerical Simulation ◽  
Cross Section ◽  
Three Dimensional ◽  
Experimental Result ◽  
Centrifugal Fan ◽  
Flow Conditions ◽  
Flow Angle ◽  
Fan Performance ◽  
Centrifugal Fans ◽  
Good Agreement

The performance of centrifugal fans is considerably influenced by the design of tongue at the re-circulation port. The flow in the volute of a centrifugal fan was studied both experimentally and numerically. In this experiment, flow angle, pressure and velocity profiles were measured at a large number of locations in the volute. The flow field in the volute passage was analyzed using Computational Fluid Dynamics. The flow was assumed to be three dimensional, turbulent and steady. The numerical simulation produced qualitatively good agreement with the experimental result. The results from experiment and numerical simulation indicated that the adoption of a re-circulating flow port improved fan performance for all flow conditions. In addition, the existence of strong secondary flow was apparent at the cross-section of the volute passage.

Numerical Calculation of Pressure Fluctuations in the Volute of a Centrifugal Fan

2005 ◽  
Vol 128 (2) ◽  
pp. 359-369 ◽  
Author(s):  
Rafael Ballesteros-Tajadura ◽  
Sandra Velarde-Suárez ◽  
Juan Pablo Hurtado-Cruz ◽  
Carlos Santolaria-Morros
Keyword(s):  
Fluid Dynamics ◽  
Pressure Fluctuations ◽  
Three Dimensional ◽  
Power Spectra ◽  
Operating Conditions ◽  
Experimental Results ◽  
Time Dependent ◽  
Centrifugal Fan ◽  
Wall Pressure Fluctuations ◽  
Good Agreement

In this work, a numerical model has been applied in order to obtain the wall pressure fluctuations at the volute of an industrial centrifugal fan. The numerical results have been compared to experimental results obtained in the same machine. 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®. This code has been employed to calculate the time-dependent pressure both in the impeller and in the volute. In this way, the pressure fluctuations in some locations over the volute wall have been obtained. The power spectra of these fluctuations have been obtained, showing an important peak at the blade passing frequency. The amplitude of this peak presents the highest values near the volute tongue, but the spatial pattern over the volute extension is different depending on the operating conditions. A good agreement has been found between the numerical and the experimental results.

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.

Experimental Characterization of the Influence of Auxiliary Devices on the Noise Generated by Industrial Centrifugal Fan and Correlation to the Geometrical and Fluid Dynamic Parameters

2011 ◽  
Author(s):  
M. Cadorin ◽  
M. Pinelli ◽  
E. Podeschi ◽  
F. Pompoli ◽  
A. Zanardi
Keyword(s):  
Fluid Dynamic ◽  
Aerodynamic Noise ◽  
Sound Power ◽  
Centrifugal Fan ◽  
Dynamic Parameters ◽  
Experimental Characterization ◽  
Noise Sources ◽  
Additional Noise ◽  
Centrifugal Fans

In recent years, the aerodynamic noise generated by centrifugal fans is receiving increasing attention because of strict environmental noise level restrictions and customer demands. The noise generated by fans is due to aerodynamic sources and to other several sources, such as, for instance, by the fan drive, by bearings and gearing, and, when present, by the inverter. Additional noise sources can be also due to structural resonance effects induced by periodic forces associated with the blade passing frequency or vortex shedding. Usually, these additional noise sources are dominated by aerodynamic noise generated by the fan, in particular when the intake and outlet of the fan are free. On the other side, if fan intake and outlet are ducted, the additional sources can relevantly contribute to overall sound generation. In this paper, an experimental characterization of the noise generated by industrial centrifugal fans when both inlet and outlet are ducted is presented. To do this, an experimental facility has been design and set up, and the sound power measured by means of the procedures outlined in the ISO 3746 international standard. A number of different type of centrifugal fan (straight-, forward- and backward blade) in different working conditions were tested, resulting in 133 different runs. These amount of data were then processed and a general formula for fan noise estimation obtained as a function of the geometrical and fluid dynamic parameters is derived. Moreover, specific coefficients with respect to blade geometry for the determination of the A-weighted frequency spectrum are presented. Finally, auxiliary devices or other features, such as inverter, thickness of the casing, acoustic insulation, electric motor shaft, are analyzed and some general rules to estimate their influence on sound power level quantified.

Investigation of Fan Rotor Interaction With Pressure Disturbance Produced by Downstream Pylon

2013 ◽  
Author(s):  
Tomonori Enoki ◽  
Hidekazu Kodama ◽  
Shinya Kusuda
Keyword(s):  
Flow Field ◽  
Three Dimensional ◽  
Numerical Results ◽  
Rotor Blades ◽  
Flow Structures ◽  
Coupled Analysis ◽  
Unsteady Forces ◽  
Rotor Stator Interaction ◽  
The Impact ◽  
Potential Pressure

This paper presents an investigation of fan rotor interaction with potential pressure disturbances produced by a downstream pylon. Three-dimensional unsteady viscous analyses are performed for two fan rotor-stator-pylon configurations with different axial gaps between the stator and the pylon, and compared with the experimental results. To clarify the impact of the rotor-pylon interaction on the potential pressure flow field, a numerical analysis for the configuration in which a fan rotor is removed is also performed and compared with the numerical results with fan rotor. Actuator disk analyses are also performed to interpret the flow structures observed in the experiments and the numerical results. It is found that a fan rotor-stator interaction also exists in the fan flow field, and this may impact on the upstream propagating potential flow that dominates the unsteady forces acting on the rotor blades. A coupled analysis between fan rotor and stator is essential to accurately predict the unsteady blade force.

Acoustic Similarity Laws for Fans

1982 ◽  
Vol 104 (2) ◽  
pp. 162-168 ◽  
Author(s):  
W. Neise ◽  
B. Barsikow
Keyword(s):  
Reynolds Number ◽  
Sound Pressure ◽  
Experimental Results ◽  
Acoustic Similarity ◽  
Fan Noise ◽  
Working Fluids ◽  
Centrifugal Fans ◽  
Noise Data ◽  
Radiated Sound ◽  
Similarity Laws

In order to verify experimentally acoustic similarity laws for fans, experiments were made with three, dimensionally similar centrifugal fans of 140, 280, and 560 mm impeller diameter. The fans were connected to anechoically terminated discharge ducts. It is shown that the influence of the Reynolds number on the radiated sound pressure is negligible within 1.4•105 ≦ Re ≦ 2.2•106, which is the range covered by the measurements. This is in agreement with earlier studies in which the Reynolds number was varied from 1.4•104 to 4.5•105. From the experimental results it is concluded that fan noise data that are taken on model fans can be extrapolated to other dimensionally similar fans of different size for arbitrary fan speeds and working fluids, provided that the operating condition and the measurement position are the same.

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