QUASI-3D ACOUSTIC MODELLING OF COMMON INTAKEAND EXHAUST COMPONENTS

The fluid dynamic processes occurring inside intake and exhaust systems of I. C. engines are one of the main noise sources in land transport vehicles. Therefore, it is considered by vehicle manufacturers as one of the factors determining the feasibility of a certain vehicle design. The generalized trend in achieving higher and higher levels of engine performances, together with social environmental concerns pushing for the introduction of increasingly severe restrictions to pollutant emissions, have led to the inclusion of different devices in the intake and exhaust systems, whose primary functions are related to emission abatement and performance enhancement (turbochargers, intercoolers and after-treatment devices). Therefore, the acoustic design of intake and exhaust systems has been affected, since these devices have a direct influence on the internal wave dynamics, and thus on intake and exhaust noise. To predict the acoustic impact of an engine equipped with these devices it becomes mandatory the adoption of simplified non linear tools. In particular non linear 1D and quasi-3D approaches can be exploited to determine the acoustic performance of devices which are usually subject to mean flow and and high amplitude pressure perturbation along with discontinuities in the temperature field