基于逆边界元法的内燃机噪声源识别方法

对内燃机复杂噪声源进行识别和排序是内燃机噪声控制的关键．基于逆边界元法（IBEM）的噪声源识别技术，利用边界元法建立了声场与结构表面振动速度之间的声学传递向量（ATV）．将常规的声压测量作为输入数据，在逆向数值计算方法的基础上能够精确地重构出结构表面法向振动速度，进而获得源面详细的振声特征信息．针对某轿车柴油机，测试了额定工况下近场144个场点声压，应用该方法在发火频率点处，重构出了柴油机表面法向振动速度分布．通过对比预测和实测声场点声压，验证了该方法的有效性．在噪声面板贡献量分析的基础上，对该柴油机各功能部件的噪声贡献量进行了排序，并得知额定工况下该柴油机的机体裙部是主要的噪声辐射部位．应用实例说明了该方法对复杂噪声源识别易于实施。具有更广的工程适应性．

Noise Sources Identification of Internal Combustion Engine Using Inverse Boundary Element Method

Noise source identification and ranking is the key step of noise control for an internal combustion engine. To avoid the limits of traditional techniques, the inverse boundary element method （ IBEM ） was used to accu- rately identify complex noise sources. The method can reconstruct the normal surface vibration velocity based on near-field sound pressures and acoustic transfer vectors （ ATVs ） between the normal surface velocity and sound field pressure calculated by the boundary element method. A diesel engine was taken as an application example. The sound pressures at 144 field points on four near-field planes of the engine were measured under 4 200 r/min rating condition. And the acoustic transfer vectors were calculated over the frequency range of interest. Based on the sound pressures and the ATVs, the normal surface velocities of the diesel engine were reconstructed by the IBEM. There was a good agreement between calculated and measured sound pressures at two reference field points. Furthermore, the panel contribution analysis of the diesel engine was implemented and the ranking of sound power contribution of each component was achieved. Results show that the skirt part of the diesel engine is the main noise source at the speed of 4 200r/min and the IBEM is suited for identification of complex noise sources.