Compact High-Pressure Intake Silencer with Multilayer Porous Material

Intake noise has become one the main concerns in the design of highly-supercharged downsized engines, which are expected to play a significant role in the upcoming years. Apart from the low frequencies associated with engine breathing, in these engines other frequency bands are also relevant which are related to the turbocharger operation, and which may radiate from the high-pressure side from the compressor outlet to the charge air cooler. Medium frequencies may be controlled with the use of different typologies of resonators, but these are not so effective for relatively high frequencies. In this paper, the potential of the use of multi-layer porous materials to control those high frequencies is explored. The material sheets are located in the side chamber of an otherwise conventional resonator, thus providing a compact, lightweight and convenient arrangement. Several configurations have been tested in an impulse rig, without and with a superimposed mean flow, and the results have been analyzed with the help of a simple linear finite volume model accounting for the material. Then, the model has been used to explore different combinations of geometry and material properties, with the purpose of defining design guidelines for a proper choice of the device size and the material used, that may allow fulfilling the targeted value.