ABSTRACT

Radiation of sound waves by a coaxial duct is considered. The coaxial duct has an inner rigid wall which is infinite, while the outer wall is rigid for $z<0$ and perforated for $z>0$ which makes the problem more interesting. Applying the Fourier transform technique, the mixed boundary value problem is described by a Wiener–Hopf equation and then the solution of the problem is found by means of the Wiener–Hopf (WH) technique. The influence of the parameters of the problem like inner and outer duct radii, frequency and porosity on the sound pressure level is displayed graphically. This study is important because of its applications in noise reduction in modern aircraft jet and turbofan engines. The current problem is also compared with subproblems with and without perforated and very good agreement is observed.

摘要

考虑同轴管道的声波辐射。同轴管道有一个无限的内刚性壁，而外壁是刚性的$z<0$并穿孔$z>0$这使问题更有趣。应用傅里叶变换技术，混合边值问题由 Wiener-Hopf 方程描述，然后通过 Wiener-Hopf (WH) 技术找到问题的解。内、外管道半径、频率和孔隙率等问题参数对声压级的影响以图形方式显示。这项研究很重要，因为它在现代飞机喷气发动机和涡扇发动机的降噪方面有应用。当前的问题也与有和没有穿孔的子问题进行了比较，观察到了非常好的一致性。