A New Criterion for Judging SI Engine In-Cylinder Pressure Development for Its Effect on Combustion Noise

Abstract

The effect of engine in-cylinder pressure development on combustion noise is studied based on measured pressure traces and the attenuation-curve theory by Austen and Priede (1958). A new criterion is proposed that correlates better to the noise levels predicted by the attenuation theory than the commonly used maximum pressure rise rate. The effect of engine bore size on combustion noise is studied next with the same engine speed, the same piston mean speed, or the same power output, respectively. For the first two cases, a smaller bore size results in a lower noise level.