Analysis of structure attenuations of gasoline engine blocks for combustion noise

摘要

Structure attenuation suggests that, to some extent, the engine structure can reduce the combustion noise. To date, though some studies have been performed on structure attenuation, these are all concentrated on diesel engines and are based on experimental approaches. We discuss here the evaluation of the structure attenuation of gasoline engine blocks using numerical analysis. Finite element analysis is conducted to calculate the normal surface velocities of a vibrating engine structure excited by combustion force. In this process, the combustion pressure and bearing load are transformed by using the wavelet transform to determine the acting faces the combustion force excites in the frequency domain. Subsequently, the boundary element analysis is performed to predict the radiated noise, which is then used to evaluate the structure attenuation. Finally, we compare the structure attenuations for the gasoline engines with the various blocks that are different in their material, skirt thickness and skirt shape.