Abstract: The mechanism of the high-frequency pressure oscillation and its effect on combustion noise are studied. The appearance ranges of the high-frequency pressure oscillation are defined by the method of the wavelet analysis and the corresponding crankshaft angle ranges of the chamber cavity model also are obtained. The acoustic model of the chamber cavity with different crankshaft angle is tested by the acoustic response method and computed by the finite element technique. Both the results of the calculated and tested are modified by corresponding crankshaft angle temperature and they are practically equal. The combustion pressure and noise are studied by the test parameters. The results show that the high-frequency pressure oscillation is aroused by the combustion chamber’s several ranks resonance. The high-frequency oscillation of combustion pressure is the important effect factor of the combustion noise.

Key words: Combustion pressure, High-frequency pressure oscillation, Internal combustion engine, Wavelet analysis