Integrating Fluid-Acoustic Unidimensional Models in the Time and Frequency Domains

In order to describe simultaneously the thermo-fluid dynamics and the acoustics of an Internal Combustion engine, a mathematical model and a computer program has been developed which integrate the Method of the Characteristics with the Acoustic. Transfer Matrix Method. The former method is currently used to model the fluid dynamics of Internal Combustion engines, whilst the latter allows the description of the acoustical behaviour of the intake and exhaust systems.

The theory presented in the article integrates the two approaches, allowing the fluid-acoustics of the global system engine-silencers to be described, taking into account the mutual interactions.

Preliminary investigations on a simplified system, constituted of a constant section duct, have demonstrated the consistency and validity of the model.