An experimental method in a real-working condition was conducted to collect acoustic emission (AE) signals emitted from cylinders of a large two-stroke low-speed marine diesel engine. Measurements were performed in an axial direction of the cylinder in medium-frequency (20–80 kHz) and high-frequency (100–900 kHz) ranges and in a vertical direction only in the medium-frequency range under two engine operating modes. The collected AE signals were analyzed in crank angle and crank angle–frequency domains. kurtosis and root mean square (RMS) parameters were employed to identify engine operating modes based on the obtained AE signals as well as investigate their characteristics. A fast Fourier transform (FFT) algorithm was also utilized to discover the frequency range of the AE signals. The results showed that only the AE signals generated by combustion processes, friction and wear, and exhaust valve opening (EVO) were partially detected. However, the AE signal radiated by the friction phenomenon was not apparent in the high-frequency range. Also, the combustion process had a strong influence on the remaining AE’s sources, especially in the axial direction of the medium-frequency range. Furthermore, the measurements should be implemented for the AE signals due to friction and wear in the medium and low frequencies; meanwhile, the combustion should be investigated in the frequency range of 200–300 kHz

进行了在实际工作条件下的实验方法，以收集从大型二冲程低速船用柴油机的气缸发出的声发射（AE）信号。在两种发动机运行模式下，仅在中频（20–80 kHz）和高频（100–900 kHz）范围内，在气缸轴​​向上进行测量，而在中频范围内，仅在垂直方向上进行测量。在曲柄角和曲柄角-频域中分析了收集的AE信号。峰度和均方根（RMS）参数用于根据获得的AE信号识别发动机运行模式并研究其特性。快速傅里叶变换（FFT）算法也被用于发现AE信号的频率范围。结果显示，仅部分检测到由燃烧过程，摩擦和磨损以及排气门打开（EVO）产生的AE信号。但是，由摩擦现象辐射的AE信号在高频范围内不明显。而且，燃烧过程对剩余的声发射源有很大的影响，特别是在中频范围的轴向上。此外，由于中低频的摩擦和磨损，应对AE信号进行测量。同时，应在200–300 kHz的频率范围内研究燃烧 燃烧过程对剩余声发射源有很大影响，尤其是在中频范围的轴向。此外，由于中低频的摩擦和磨损，应对AE信号进行测量。同时，应在200–300 kHz的频率范围内研究燃烧 燃烧过程对剩余声发射源有很大影响，尤其是在中频范围的轴向。此外，由于中低频的摩擦和磨损，应对AE信号进行测量。同时，应在200–300 kHz的频率范围内研究燃烧