用特征线法和传递矩阵法解析预报柴油机排气噪声

Prediction of Diesel Engine Exhaust Noise by Characteristics-Transmission Matrix Method

本文介绍纯解析预报多缸柴油机排气消声系统声学性能的一般步骤。在此方法中,通过用特征线法计算柴油机排气的不稳定流动过程和依靠所谓双负载法确定柴油机的声源强度和阻抗特性,然后利用传递矩阵法预报柴油机排气系统出口的辐射噪声级和消声器的插入损失。对一台四缸柴油机进行计算,其计算结果与实测数据相吻合。

A general scheme for analytical preliction of acoustic performance of multi-cylinder diesel engine exhaust muffler systems is presented. The acoustic source impedance and strength were determined by means of combination of unsteady flow analysis by the method of characteristics with so-called two-load method, and the noise levels emanated from the exhaust system opening and the insertion loss of the muffler were predicted by linear acoustic analysis, i.e., the method of transmission matrix. Calculated results for a four-cylinder diesel engine were in good agreement with the measured ones.