利用小波分析技术研究燃烧压力高频振荡

为研究内燃机缸内压力高频振荡的机理以及压力高频振荡对燃烧噪声的影响，利用小波分析提取缸内压力高频成分，确定缸内压力高频振荡出现的范围．用有限元方法计算不同曲轴转角下对应燃烧室空腔声模态，用声响应法测量不同曲轴转角下燃烧室空腔声模态，并对计算值和测量值进行比较和修正．对实测的缸内燃烧压力信号进行了分析．有限元计算结果与模态试验结果较吻合，声模态修正后的结果能很好地解释缸内燃烧压力高频振荡．研究表明，缸内燃烧压力高频振荡是燃烧室空腔共振引起的，燃烧压力高频振荡是影响燃烧噪声的重要因素．

Study on High-Frequency Pressure Oscillation of Combustion Pressure through Wavelet Analysis

In order to study the mechanism of the high-frequency pressure oscillation and its effect on combustion noise in the cylinder of internal combustion engine,the appearance ranges of the high-frequency pressure oscillation are defined by wavelet analysis. The acoustic model of the chamber cavity with different crankshaft angle is tested by acoustic response and computed by the finite element technique. The results of the calculation and test are modified by corresponding crankshaft angle temperature,and they are practically equal and can exactly explain the high-frequency oscillation of combustion pressure.The combustion pressure and noise are studied by test parameters. The results show that the high-frequency pressure oscillation is aroused by the combustion chamber's resonance. The high-frequency oscillation of combustion pressure is the important factor determing the level of the combustion noise.