Transactions of the Korean Society of Mechanical Engineers B (대한기계학회논문집B)

The Korean Society of Mechanical Engineers (대한기계학회)
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An Analysis of the Flow Field and Radiation Acoustic Field of a Centrifugal Impeller with Wedge(I) -An Analysis of the Flow Field and Aeroacoustic Source-

웨지가 있는 원심 임펠러의 유동 및 방사 음향장 해석(I) -유동장 및 소음원 해석-

  • Published : 2001.09.01
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Abstract

Centrifugal fans are widely used and the noise generated by these machines causes one of the most serious problems. In general, the centrifugal fan noise is often dominated by tones at BPF(blade passage frequency) and its higher harmonics. This is a consequence of the strong interaction between the flow discharged from the impeller and the cutoff in the casing. However, only a few research have been carried out on predicting the noise because of the difficulty in obtaining detailed information about the flow field and casing effects on noise radiation. The objective of this study is to understand the generation mechanism of sound and to develop a prediction method for the unsteady flow field and the acoustic pressure field of a centrifugal fan. We assume that the impeller rotates with a constant angular velocity and the flow field of the impeller is incompressible and inviscid. So, a discrete vortex method(DVM) is used to model the centrifugal fan and to calculate the flow field. The force of each element on the blade is calculated by the unsteady Bernoulli equation. Lowsons method is used to predict the acoustic source. In order to compare the experimental data, a centrifugal impeller and wedge introduced by Weidemann are used in the numerical calculation and the results are compared with the experimental data. Reasonable results are obtained not only for the peak frequencies but also for the amplitudes of the tonal.

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References

  1. Cory, W. T. W., 1992, 'Short History of Mechanical Fans and the Measurement of Their Noise,' An International INCE Symposium, pp. 3-44
  2. Madison, R. D., 1949, Fan Engineering, Buffalo Forge Company, 5th Edition
  3. Deming, A. Fm '1938, Noise from Propellers with Symmetrical Sections at Zero Blade Angle,' NASA TN No. 679
  4. Gutin, L., 1984, 'On the Sound Field of a Rotating Airscrew,' English Translation NACA TM No. TM1195
  5. Neise, W., 1976, 'Noise Reduction in Centrifugal Fans : A Literature Survey,' Journal of Sound and Vibration, Vol. 45, pp. 375-403 https://doi.org/10.1016/0022-460X(76)90394-1
  6. Neise, W., 1982, 'Review of Noise Reduction Methods for Centrifugal Fans,' J. of Engineering for Industry, Vol. 104, pp. 151-161
  7. Chanaud, R. C., 1965, 'Aerodynamic Sound from Centrifugal-Fan Rotors,' Journal of the Aeroacoustical Society of America, Vol. 37, pp.969-974 https://doi.org/10.1121/1.1909566
  8. Weidemann, J., 1971, 'Analysis of the relations between acoustic aerodynamic parameters for a series of dimensionally similar centrifugal fan rotors,' NASA TT F-13,798
  9. Neise, W., 1975, 'Application of Similarity Laws to the Blade Passage Sound of Centrifugal Fans,' Journal of Sound and Vibration, Vol. 43, No. 1, pp. 61-75 https://doi.org/10.1016/0022-460X(75)90205-9
  10. Neise, W. and Barsikow, B., 1982, 'Acoustic Similarity Laws for Fans,' Trans. of the ASME, Vol. 104, pp. 162-168
  11. Kim, J. W. and Lee, D. J., 1995, 'Optimized Compact Finite Difference Schemes with Maximum Resolution', AIAA Journal, Vol.34, No. 5
  12. Young J. Moon and Cho Young, 1998, 'Numerical Prediction of the Cross-flow Fan Performances and Noise Characteristics by Unstructured Flow Slover Algorithm,' Proc. of 4th KSME-JSME Fluids Eng. Con., pp. 185-188
  13. M. V. Lowson, 1965, 'The Sound Field for Singularities in Motion,' Proc. R. Soc. London, Ser. A. 286, pp.559-572
  14. 전완호, 이덕주, 1999, '수치기법을 이용한 원심홴 소음의 음향학적 상사법칙 적용,' 한국소음진동공학회지, 제 9 권, 제 5호, pp. 101-111
  15. Jeon, W. H. and Lee, D. J., 1999, 'An Analysis of the Flow and Aerodynamic Acoustic Sources of a Centrifugal Impeller,' Journal of Sound and Vibration, Vol. 222, No. 3, pp. 505-511 https://doi.org/10.1006/jsvi.1998.1983
  16. Neise, W., 1992, 'Review if Fan Noise Generation Mechanism and Control Method,' An International INCE Symposium, pp. 45-56