고차스펙트럼과 기계적 시스템의 응용연구(2)-기관 배기관내의 조화파 상호작용 해석-

Higher Order Spectra and Their Application to Mechanical Systems(II) -Analysis on the Interactions of Harmonics in Exhaust Pipe of Engines-

The pulsating pressure waves are composed of fundamental frequency and higher order harmonics in exhaust pipe of engines. The nonlinearity in exhaust pipe is caused by their interactions. The error which is between prediction and measurement is induced by the nonlinearity. We can not explain this phenomenon using linear acoustic theory which is existing theory. So power spectrum which was used in linear theory is not useful. Bispectrum and bicoherence functions which are a higher order spectrum are applicable to explain this phenomenon. This paper proposes a nonlinear effect of pulsating pressure waves. The phenomenon proposed here is identified by using of higher order spectrum density functions.