Backpressure considerations in designing of cross flow perforated-element reactive silencers

A computational fluid dynamics (CFD) based three-dimensional analysis has been undertaken using a commercial software to evaluate the pressure drop characteristics of four major backpressure-intensive components of automotive mufflers. Empirical expressions have been derived to relate the normalized pressure drop across these elements to the most significantly affecting parameters of the configuration. These expressions have been derived in a manner such that they can be used to evaluate the total pressure drop across complex mufflers constituting these basic elements. Effect of perforation diameter on the pressure drop in the cross-flow elements has been investigated. Techniques are proposed to achieve lower backpressure without significantly affecting the transmission loss performance, with the same overall length and volume of the muffler.