Journal of Mechanical Science and Technology

The Korean Society of Mechanical Engineers (대한기계학회)
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Analysis on the Interactions of Harmonics in Exhaust Pipes of Automotive Engines

  • Lee, Min-Ho (Graduate School of Mechanical Engineering, Myong-Ji University) ;
  • Lee, Joon-Seo (Department of Mechanical Design, Chung-Cheong College) ;
  • Cha, Kyung-Ok (Department of Mechanical Engineering, Myong-Ji University)
  • Published : 2003.12.01
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Abstract

In exhaust pipes of automotive engines, the pulsating pressure waves are composed of fundamental frequency and high order harmonics. The nonlinearities in the exhaust pipe is caused by their interactions. The error between prediction and measurement is induced by the nonlinearities. We can not explain this phenomenon using linear acoustics theory. So power spectrum, which is used in linear theory, is not useful. This paper is concerned with the development of useful engineering techniques to detect and analyze nonlinearity in exhaust pipe of automotive engines. The study of higher order statistics has been dominated by work on the bispectrum. The bispectrum can be viewed as a decomposition of the third moment (skewness) of a signal over frequency and as such is blind to symmetric nonlinearities. The phenomenon of quadratic phase coupling (QPC) can be analyzed by the bicoherence function. Finally the application of these techniques to data from actual exhaust pipe systems is performed.

Keywords

References

  1. Bendat, J. S. and Piersol, A. G., 1993, 'Engineering Applications of Correlation and Spectral Analysis,' 2nd Edition, John Wiley & Sons Inc
  2. Davis, P. O. A. L., 1964, 'The Design of Silencers for Internal Combustion Engines,' J. Sound and Vibration, Vol. 1, No.2, p. 185 https://doi.org/10.1016/0022-460X(64)90081-1
  3. Eizo Suyama and Takashi Ishida, 1990, 'The Optimum Setting Position of the Silencer,' J. SAE, No. 900348
  4. Lyon, R. H., 1975, 'Statistical Energy Analysis of Dynamical Systems,' MIT Press, Cambridge, Massachusetts
  5. Miksad, R. W., Jones, F. L. and Powers, E. J. 1983, 'Measurements of Nonlinear Interactions During Natural Transition of a Symmetric Wake,' Physics of Fluids, Vol. 26, No.6, pp. 1402-1407 https://doi.org/10.1063/1.864309
  6. Mood, A., Graybill, F. A. and Boes, D. C., 1974, 'Introduction to the Theory of Statistics,' McGraw-Hill
  7. Nikias, C. L. and Mendel, J. M., 1993, 'Signal Processing with Higher-Order Spectra,' IEEE Signal Processing Magazine, pp. 11-37 https://doi.org/10.1109/79.221324
  8. Nikias, C. L. and Petropula, A. P., 1993, 'Higher Order Spectra Analysis - A Nonlinear Signal Processing Framework,' Prentice Hall
  9. Nikias, C. L. and Raghuveer, M. R., 1987, 'Bispectrum Estimation: A Digital Signal Processing Framework,' Processing of the IEEE, Vol. 75, No.7, pp. 869-891
  10. Priestley, M. B., 1981, 'Spectral Analysis and Time Series,' Academic Press
  11. Seybert, A. F. and Hamilton, J. F., 1978, 'Time delay Bias Errors in Estimating Frequency Response and Coherence Functions,' J. Sound and Vibration, Vol. 60, No. 1, p. 1 https://doi.org/10.1016/0022-460X(78)90396-6