Prediction of Aerodynamic Noise Level of Cross-Flow Fans for Air Conditioners (2nd Report, Development of Cross-Flow Fans by means of Aerodynamic Noise Prediction Model)

We have developed a prediction model for the overall level of aeroacoustic noise generated by cross-flow fans. It is based on two assumptions: the velocities along the outside edge of the impeller have an especially close relation to the noise levels, and the noise levels are in proportion to the sixth power of the relative velocities at the edge of the blade. A computational fluid dynamics is used to obtain the necessary velocity-field data for this prediction model. The predicted noise levels of a test impeller for different flow coefficients are in good agreement with the measured results. This means that variations in noise levels with the flow coefficient can be described accurately by the prediction model, which should prove to be a useful tool for speeding up the development of silent cross-flow fans.

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Streamline Computation Study on Rotation Aerodynamic Noise Prediction of Cross-flow Fan

Acoustical Physics ◽

10.1134/s1063771019040110 ◽

2019 ◽

Vol 65 (4) ◽

pp. 418-431

Author(s):

Hui Li

Keyword(s):

Cross Flow ◽

Aerodynamic Noise ◽

Noise Prediction ◽

Cross Flow Fan

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

Journal of Fluids Engineering ◽

10.1115/1.2953229 ◽

2008 ◽

Vol 130 (9) ◽

Cited By ~ 21

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.

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The Research of Airport Noise Prediction

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.610-613.2571 ◽

2012 ◽

Vol 610-613 ◽

pp. 2571-2577

Author(s):

Wei Jun Pan ◽

Yuan Yuan Zheng ◽

Yu Hua Feng

Keyword(s):

Prediction Model ◽

Noise Level ◽

Measurement Data ◽

Noise Pollution ◽

High Accuracy ◽

Noise Prediction ◽

Paper Study ◽

Limited Data ◽

New Model ◽

Future Prediction

Airport noise is noise pollution produced by any aircraft or its components, during various phases of a flight,especially the landing phases. This paper study the airport noise prediction model basing on WECPNL(Weighted Equivalent Continuous Perceive Noise Level) recommended by ICAO as a index. With the measurement data,which is properly distribute to the final of active runway and centerline, a brief summary of WECPNL-based prediction model from touchdown to runway centerline is established. However, the results showed a discrepancy of certain points was between prediction and measurement data, especially 1.5-2.5km away from the airport. Therefore, an amendment was proposed with greater accuracy, which the relative of the new model for future prediction ranged from 1.0% to 2.0%. To some extent, this model also can reflect and make full use of the limited data with a high accuracy, especially suit for monitoring rapidly in some new small airports.

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Road Traffic Noise Prediction Model

PARIPEX-INDIAN JOURNAL OF RESEARCH ◽

10.15373/22501991/apr2014/34 ◽

2012 ◽

Vol 3 (4) ◽

pp. 110-112

Author(s):

Rahul Singh ◽

◽

Parveen Bawa ◽

Ranjan Kumar Thakur

Keyword(s):

Prediction Model ◽

Road Traffic ◽

Traffic Noise ◽

Road Traffic Noise ◽

Noise Prediction

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Mechanical and Aerodynamic Noise Prediction for Electric Vehicle Traction Motor and Its Validation

10.4271/2017-26-0270 ◽

2017 ◽

Cited By ~ 2

Author(s):

Rahul Gurav ◽

Kishor D Udawant ◽

Ramkumar Rajamanickam ◽

N V Karanth ◽

S R Marathe

Keyword(s):

Electric Vehicle ◽

Aerodynamic Noise ◽

Noise Prediction ◽

Traction Motor

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The Influence of the Exit Velocity Profile on the Noise of a Jet

Aeronautical Quarterly ◽

10.1017/s0001925900000974 ◽

1954 ◽

Vol 4 (4) ◽

pp. 341-360 ◽

Cited By ~ 11

Author(s):

Alan Powell

Keyword(s):

Velocity Profile ◽

Noise Level ◽

Turbulent Pipe Flow ◽

Aerodynamic Noise ◽

Noise Levels ◽

Flow Forming ◽

Flow Velocity Profile ◽

Jet Velocity ◽

Initial Turbulence ◽

Moving Fluid

SummaryThe noise levels of a jet issuing from a long pipe are compared with those of a jet having a square velocity profile at the exit. A subsonic noise reduction of between 2 and 5 decibels for various conditions is found for the case of the flow emerging with an approximately “turbulent pipe-flow” velocity profile for the same maximum jet velocity, but this is at the expense of a loss in thrust of a quarter. On comparison with a jet of smaller diameter which has an equal thrust for the same maximum jet velocity, it is found that the changes in noise level are rather smaller. For jets of equal diameters, the effects on the subsonic aerodynamic noise generated of a reduction of velocity gradient near the boundary are more than offset by the increased velocities necessary near the centre of the jet to obtain equal thrust. It is concluded that if the effect of differences in initial turbulence can be neglected the use of an auxiliary flow forming a comparatively thin sheath of slower moving fluid at the exit is not likely to result in large decreases in the subsonic noise level, and that a general reduction in jet velocity is more effective.Above the critical pressure larger reductions of up to 10 decibels are found. These are consistent with a delay of the onset of the self-maintained shock-produced noise.

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