Investigation on the flow noise propagation mechanism in simple expansion pipelines based on synergy principle of flow and sound fields

The noise pollution in pipelines exists for a long time and cant be ignored in modern industries. It is important to investigate the transfer mechanism of sound energy in pipelines and develop high efficiency mufflers with low penalty of pressure drop. Different with the traditional method, this study is focused on the flow and sound fields synergy principle to investigate the flow noise propagation mechanism in reactive mufflers. In this study, theoretical analysis and numerical simulation methods are coupled to investigate the noise propagation process. In the theoretical analysis aspect, the synergetic relationships between the flow and pressure gradient fields are deduced and the field synergy theory is established. In the numerical simulation aspect, the flow noise propagation process in the simple expansion chamber mufflers is studied. The results show that with the decrease of synergy between flow and sound fields, the work done by the fluid on the wall decreases, which means the exchange of sound energy between the wall and the fluid decreases. (C) 2017 The Authors. Published by Elsevier Ltd.