飞机噪声的工程预测

 本文将飞机在飞行过程中发出声辐射的动态问题,按准稳态方法分解为航迹,观察点与声源的几何关系,声源特性、大气衰减与地面效应等单元过程。并以涡扇飞机和螺旋桨飞机等计算实例,阐明飞机噪声的组成,时间历程、频谱,指向性及地面等值线等同公共噪声和声疲劳有密切关系的问题。

THE INTERIM PREDICTION FOR AIRCRAFT NOISE

The acoustic emission from an aircraft during the flight is a dynamic process. The emitting acoustic power and received mean square acoustic pressure are the function of time. The paper deals with this problem as a quasi-steady one. The whole process is resolved into several elementary procedures,for example ,the flight trajectory,the geometric relation between the noise sources and observers,the noise source characteristics,the air propagation and ground effect. Two calculation examples are given in the paper,one for a long-range passenger with high bypass-ratio turbofan engine,another for a 3-leaved propeller. The composition of aircraft noise,and its time record,frequency spectrum and directivity can be clearly described by these curves. It may be useful for the designer to perform the acoustic design of his aircraft layout.