基于独立分量分析和时频分析的柴油机燃烧噪声研究Ⅱ:预喷射影响分析

Study on Diesel Combustion Noise Based on Independent Component Analysis and Time Frequency Analysis-Part II: Effect of pilot injection

柴油机噪声各个分量互相交错重叠,时域截断和频域分析难以准确提取燃烧噪声。介绍了基于独立分量分析和时频分析的时频联合域内的滤波方法。燃烧噪声的独立分量提供了关于燃烧噪声的时间信息和频率分布特征,根据其时频分布构造时频通域,并对实际噪声信号进行时频滤波,可以得到燃烧噪声的时频分布。在此基础上,可以计算燃烧噪声的强弱。分析表明,在大部分测点,有预喷射的燃烧噪声低于无预喷射的燃烧噪声,说明预喷射可以降低柴油机的燃烧噪声。

The components of diesel noise overlap with each other, so the time window and spectral analysis are not very effective in extracting combustion noise. The method of time frequency filtering based on independent component analysis are introduced. The independent component of combustion noise provides the time location and spectral distribution information about the combustion noise, so a time frequency coveting region can be constructed accordingly, and applied to filter the measured noise signal. Time frequency distribution of combustion noise can be derived. Furthermore, the combustion noise intensity can be calculated. It is found that the combustion noise intensity under pilot injection is lower than that without pilot injection at most of the measurement points. This indicates that pilot injection can decrease combustion noise of diesel engines.