Both theoretically as well as in many applications like exhaust systems, ventilation pipes, mufflers, air intakes and also large scale industrial smoke stacks, it is of interest to understand how sound waves are scattered at duct exists. Especially for aeronautical application such as jet engines, the effect of coupling of acoustics and flow on sound radiation and reflection from a duct termination in a uniform is an important problem.
In order to predict the acoustic performance in duct systems, it is essential to know how the incoming acoustic waves are propagated and transmitted and reflected. This thesis work aims at developing suitable simulation methods as extension to existing software and to validate these methods to experimental measurements and theory.
Firstly, numerical simulations of fully developed flow through a duct exit has been carried out. The goal in this part is to obtain the mean values for the velocity and pressure. The commercial code Fluent 12.1 is used for numerical simulations in two space dimensions. Secondly, numerical simulations of the acoustic part has been studied with the commercial software Comsol 3.5a with the objective to investigate the ability of the frequency domain Navier-Stokes equations to the characteristic properties of the acoustics at the duct termination.
Finally, numerical results are compared to available experimental results with acceptable agreement which shows successes and also constraints of the simulations.
Author: Sedarati, Parinaz