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Engineers need the most capable design support tools to reconcile the demands of the market, legislation, economic design and production. Simulation tools are a very effective support system. The optimization of the complete vehicle system for external noise radiation is very complex due to the interaction of the engine performance with the vehicle positioning. Simple predictive methods and assumptions are often not usefully accurate. The work described here covers an approach to combining rapid predictions of engine and vehicle performance with those of radiated noise from the various significant subsystems, to produce a useful, rapid, prediction tool for complete vehicle noise. A mono-dimensional gas flow code is used to provide a sufficiently accurate prediction of the engine power for vehicle performance prediction and also the noise output of intake and exhaust systems. Various approximate prediction methods are used to assemble an overall vehicle radiated noise prediction.

A calculation method has been developed to analyze and to optimize both the acoustic and performance aspects of air intake systems for internal combustion engines. The method integrates an acoustic linear one-dimensional computer code (SISASP) together with an acoustic linear three-dimensional computer code (SYSNOISE) and a one-dimensional thermodynamics analysis code (MARKPLUS XIV). The method enables the design of complete intake systems, integrating the acoustic and performance aspects and allows the designer to optimize the design to achieve legal, subjective comfort and engine performance targets. The results obtained from system simulations carried out in this way have been validated on a four cylinder gasoline engine and are illustrated here. The method can be used as part of the overall integrated design of an engine and also as a tool for intake system optimization.