Acoustic Study on Tubular Micro-perforated Flow Plug Sections in Vehicle Silencer’s Application
Today, after a rapid publicity growth in the last decades, micro-perforated acoustic elements (MP) are widely applied for broadband sound absorption in internal combustion engine exhaust systems. Most typically the MP’s are exposed into a grazing flow conditions, for which a relatively good knowledge and respectable acoustic models exist. However, in certain exhaust system designs an alternative layout for tubular flow duct MP elements – the flow plug condition is useful. In this type of MP’s application all the exhaust gas flow is guided through the micro-perforated sections upstream and downstream of the plug, typically increasing the flow resistivity, and viscous damping of the propagating noise. This MP’s type also appears to be a considerably less studied one, whereas only a few dedicated papers can be found.