虚拟预测方法在柴油机低噪声设计中的应用

为了降低柴油机的整机噪声，采用虚拟预测方法对该发动机的机体进行了低噪声改进设计.该虚拟预测方法采用了多体动力学法 有限元法 声学仿真法的集成预测方法， 用多体动力学分析机体承受的动态载荷，用有限元法分析载荷作用下的动态响应. 用声学仿真法分析了由机体表面的振动而辐射的噪声.依据该方法提供的振动与声学信息，对某发动机的机体和曲轴箱结构进行了改进，并比较了机体上某点的振动加速度值和辐射噪声值.结果表明，该虚拟预测方法的结果与试验结果吻合较好.改进后机体上与辐射噪声较大的薄壁件连接部位的振动显著降低，机体的噪声也得到了降低.

Application of virtual prediction method to low-noise diesel engine design

To reduce a diesel engine's overall noise,an improved noise reduction design method for the engine block was proposed based on virtual prediction method.The integrated prediction method was comprised of the multibody-dynamic method,finite element method and acoustic simulation method.When the dynamic load supported by the engine block was simulated using multibody-dynamic method,dynamic response under the dynamic load was analyzed adopting finite element method,and the noise radiation of surface vibration in the engine block was calculated utilizing acoustic simulation method.Based of the information of vibration and acoustics provided by the method,structures of the engine block and bend shaft box were modified.Vibration acceleration of the engine block and noise radiation of one point were studied.The results show that virtual prediction data agree very well with test data.The vibrations of improved engine block are dramatically reduced at the locations connected to thin wall accessories with large radiated noise,and the noise of the engine block is decreased.