汽车发动机排气消声器性能的计算机模拟研究

该文用传递矩阵法模拟计算消声器的插入损失。用以评价包括原阻抗及尾管辐射阳抗在内的整个排气系统的声学特性。推导出六种消声单元的传递矩阵。并应用于插入损失计算之中。建立了消声量的数学模型，用以分析消声器本身特性与声波衰减之间的关系，并以消声量为目标函数，对消声器进行了优化设计。建立了压力损失的数学模型，来评价消声器的空气动力性能。采用均匀流和非线性温度梯度，并将三维谱图应用于消声器的性能分析之中。编写了消声器性能计算软件，用所编软件对自制的四个不同结构消声器进行了性能计算及代化设计，同时进行了排气消声器的性能试验，试验结果与预测结果吻合较好。该文开发的软件在消声器CAD方面具有一定的应用前景。

Computer Simulation for the Performance of Automobile Engine Silencer

By transmission matrix method, the simulation of insertion loss of automobile exhaust silencer, which is useful to evaluating the acoustic performance of the exhaust system,is made in this academic thesis. Six new sound field transmission matrixes for silencing elements are established and used for the insertion loss calculation. Mathematics model of thesound attenuation is set up and used in analyzing the relation between acoustic pressure attenuation and silencer structure characteristics. The silencer has been optimized by taking the sound attenuation as objective function. A computing model for calculation the pressure loss in a silencer is built and used for ana1ysis the aerodynamlcal performance of the silencer. The characteristic calculation of the silencer performance and optimization software has been designed, in which mean flow and nonlinear temperature gradient is taken into account, and three-dimension spectrum is used in the silencer performance analysis. The program is used in the characteristic calculation of the performance of the four self-made silencers and their optimizing design. Experiments 'show the good agreement between theory calculation and test results. The software wil1 be helpful for further research in silencer CAD.