陈卓群，杨贵春，冯垣洁，张强，高云峰

（中国北方发动机研究所，天津  300000）

    摘要：文章对模态扩展的基本理论进行了阐述，并以准确的有限元模型和试验振动数据作为输入，应用模态扩展和边界元法求得某大型高速V6柴油机的整机结构辐射噪声，计算结果表明发动机的爆发压力、不平衡惯性力是低频辐射噪声的主要贡献者，而高频辐射噪声的主要来源是齿轮传动产生的振动激励，发动机本体模态对整机辐射噪声贡献相对较小。该实例充分验证了模态扩展的准确性和实用性，为后续发动机的振动和噪声控制指明了方向。

    关键词：模态扩展；边界元法；辐射噪声

Abstract: The modal expansion theory is elaborated in this paper. Taking precise finite element model and vibration data from experiments, we got a large high speed V6 diesel engine’s whole structure radiation noise by modal expansion and boundary element method. The results show that the low frequency radiation noise mainly comes from the combustion pressure and unbalance inertia force of engine. While the high frequency radiation noise from the vibration excitation of gear transmission. And the engine body’s modal has little radiation noise for whole set. The true case study gives a confirmation for accuracy and usability of modal expansion and a reference for vibration and noise of diesel engine.

Key Words: Modal Expansion；Boundary Element Method； Radiation Noise