Technical Paper
The Condition Monitoring of Diesel Engines Using Acoustic Measurements Part 1: Acoustic Characteristics of the Engine and Representation of the Acoustic Signals
2000-03-06
2000-01-0730
In this, Part 1 of the paper, the sound generation of a diesel engine is modelled based upon the combustion process, and time-frequency analysis is used to reveal the underlying characteristics of the sound waves. Simulation shows that the frequency bandwidth of the generated acoustic signals is significantly widened around the engine's top dead centre (TDC) positions, with the energy concentrated predominantly at the firing frequency and its harmonics. As anticipated, the model predicts an increase in sound level with increasing engine load and speed, and the model-predicted noise generation is correlated with waveforms extracted from intrusively-monitored cylinder pressure. Real monitored data, taken in an ordinary engine test-bay environment and without special acoustic monitoring precautions, is shown to be highly contaminated due to adverse environmental acoustics and intrusive background noise.
