Relation between Form of Cylinder-Pressure Diagram and Noise in Diesel Engines

Abstract

This paper is a sequel to an earlier paper and carries this aspect of the investigation on from that stage. The frequency analysis of cylinder pressure has been shown to be a satisfactory criterion of the ‘noisiness’ of a cylinder-pressure diagram. In this paper the effect of the properties of the measuring equipment, such as band width, is considered so that the results may be interpreted quantitatively in terms of the pressure rises and hence the amount of combustion involved. The effect of operating variables on the frequency analysis is investigated. In some cases stroke-to-stroke variations are of importance and frequency analysis and emitted noise are compared in relation to background noise. Over a limited range, the effect of type of combustion chamber has been explored and some observations with petrol as the fuel are included.