Sound radiation of circular tube with finite wall thickness

Here, to study sound radiation characteristics of a circular tube with finite wall thickness, a 2-D axisymmetric time-domain computational fluid dynamic ( CFD ) method was used to calculate orifice reflection coefficient and end correction. The calculation results of infinitely thin circular pipeline agreed well with the theoretical values to prove the correctness of the calculation method. Effects of wall thickness on sound radiation of pipe mouth were studied, and the calculation results showed that with increase in wall thickness, amplitude of reflection coefficient gradually decreases, while end correction coefficient obviously increases. By fitting calculation results with polynomial, fitting formulas for reflection coefficient and end correction were deduced. Finally, fitting formulas were adopted to calculate the radiated acoustic impedance of orifice and noise reduction ( NR ) of a finite wall thickness expansion cavity muffler combining the finite element method. The correctness and practicality of fitting formulas were verified by comparing their results with those calculated with an automatic matching layer. © 2024 Chinese Vibration Engineering Society. All rights reserved.