Combustion-Impact-Energy Accumulation, Decay and Noise Radiation in Diesel Engines

Abstract

Engine noise is generally classified into the combustion noise and mechanical noise. The combustion noise level is often estimated in frequency domain using the in-cylinder pressure level and structural attenuation of the engine. The noise level in diesel engines rapidly increases near the combustion TDC and shows a great value in the expansion stroke in time-frequency domain while the in-cylinder pressure level shows a great value only near the combustion TDC. The present paper introduces an engine noise generation model which considers such time-frequency characteristics of in-cylinder pressure and engine noise and physical processes, such as combustion-impact-energy accumulation, decay and noise radiation. The effect of noise-cancelling spike combustion is also analyzed by this model.