Fault diagnosis of a diesel engine by using the analysis of instantaneous angular speed with a flexible model

Engine shaft instantaneous angular speed (IAS) can be used to diagnose combustion related faults and other faults affecting the output of engines, especially for small-scale diesel generators. Unfortunately, it is difficult to apply this technology to monitoring the operational condition of a marine propulsion diesel engine due to its complex shafting systems and multiple factors affecting the shafting torsional vibration. In this paper, the characteristics of fault detection based on traditional IAS analysis methods are firstly analysed. A novel method has been developed based on treating the engine shaft system as a flexible model, aiming to extend the IAS technique to monitor the working condition of a large marine diesel engine. Theoretical studies and engine evaluation tests have been conducted on a marine diesel engine experiment set-up. It is shown that an integration of the developed flexible model with traditional IAS technique is feasible and accurate