Monitoring of Diesel Engine Combustions Based on the Acoustic Source Characterisation of the Exhaust System

Acoustic methods are among the most useful techniques for monitoring the condition of machines. However, the
influence of background noise is a major issue in implementing this method. This paper introduces an effective monitoring
approach to diesel engine combustion based on acoustic one-port source theory and exhaust acoustic measurements. It has
been found that the strength, in terms of pressure, of the engine acoustic source is able to provide a more accurate
representation of the engine combustion because it is obtained by minimising the reflection effects in the exhaust system.
A multi-load acoustic method was then developed to determine the pressure signal when a four-cylinder diesel engine was
tested with faults in the fuel injector and exhaust valve. From the experimental results, it is shown that a two-load acoustic
method is sufficient to permit the detection and diagnosis of abnormalities in the pressure signal, caused by the faults. This
then provides a novel and yet reliable method to achieve condition monitoring of diesel engines even if they operate in high
noise environments such as standby power stations and vessel chambers.