Analysis of noise occurrence by cavitation in the main bearing of diesel engine

This paper presents an analysis of noise occurrence at the 7th main bearing of an inline six cylinder diesel engine. From experimental results of the engine, it seems that cavitation in the bearing oil film is a major factor for this noise, and the noise occurs with a combination of the following conditions; (1) cavitation exists in oil film at the main bearing, (2) main journal is unstable and (3) excitation force acts at this moment. This assumption is analyzed using engine vibration analysis, EHL analysis and stability analysis. The results agree with the condition of the noise occurrence.