Multiple and Single Input Techniques Applied to the Noise and Vibration of a Medium Power Diesel Engine

The periodic nature of the sources of noise and vibration in an internal combustion engine creates a number of problems when the relative importance of the contribution of each source to the noise or vibration is required.Classical methods of signal processing yield results that can overestimate the contributions from an individual source because of the high degree of coherence existing between most of the sources.Methods of treating the problem of multiple partially coherent sources have existed for some time and were first applied to the Diesel Engine by Chung et al. [I] in 1973.After a short period of interest they have virtually creased to be applied to this type of problem because of the generally unsatisfactory results obtained.The simplifications and approximations requiered to obtain results that match with physical reality have limited the utility of the final result.This paper describes the application of these techniques to a medium power diesel engine and the ways that have been found of improving the accuracy of the