内燃机排气噪声是内燃机的主要噪声源。本文对产生排气噪声的机理进行了理论探讨。认为内燃机排气噪声属于空气动力性噪声,主要是在排气阀附近区域中排气流紊动扩散引起的。在低频域,内燃机排气噪声具有简单源特性;在中、高频域排气噪声具有四极子源特性。 Engine exhaust noise is the main source of noise for internal combustion engines. In this paper, the mechanism of exhaust noise is theoretically discussed. It is considered that the exhaust noise of the internal combustion engine is aerodynamic noise, mainly caused by the turbulent diffusion of the exhaust gas flow in the vicinity of the exhaust valve. In the low frequency range, the exhaust noise of the internal combustion engine has a simple source characteristic; the exhaust noise in the middle and high frequency regions has a quadrupole source characteristic.