阶次跟踪及发动机排气非稳态噪声分析

Order-Tracking and Its Application to the Analysis of Engine Exhaust Unsteady Noise

汽车加速过程排气噪声是一种强非稳态的噪声,使用传统的频谱分析方法往往会出现"频率模糊"现象。为了了解发动机加速阶段排气噪声特性、研究发动机转速对加速过程排气噪声的影响,采用了阶次跟踪方法对某四缸发动机加速过程排气噪声进行了测试,分析了发动机加速过程排气噪声的主要阶次及主要噪声源,揭示了发动机排气噪声声压级变化与发动机转速的关系,为该发动机排气消声器的设计和优化提供了重要的参考依据。

Exhaust noise of vehicles at speed--up state is strongly unsteady. When analyzing the noise with traditional spectrum analysis, the ＂frequency smear＂ can hardly be avoided, In order to understand the acceleration noise properties and engine speed＇s influence exactly, an effective method, whieh is order tracking, is utilized to anal）ze the exhaust, st noise of a fiur- stroke engine. Further, the main order components and main sources of acceleration exhaust noise are analyzed, the relationship between exhanst noise＇ sound pressure level and engine rotation speed is revealed. Sueh analysis results will provide some preference and essential reJerence for exhataust muffler design and optimization.