Air Intake Development - Effects of Coupled Fluid/Structure Modes

The design of an air intake system has to be a compromise between several system targets. In the past these conflicts were solved with experimental test on the first prototype parts.

To shorten the development times more and more computational programs in the concept phase are used.

1D simulation programs are based on the transfer matrix method or use the output of gas exchange programs to simulate the acoustic behavior of air intake systems. These tools do usually neglect the coupled fluid/structure modes.

Measurements on a simple air cleaner design have shown that these coupling can not be ignored on typical air cleaner designs. The difference between internal and external pressure leads to an increase of the air cleaner volume which shifts the first resonance to a lower engine speed.

This paper shows a method which can be used in 1D simulation programs to allow the prediction of orifice noise of air intake systems.