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The paper describes a comparative analysis between numerical and experimental study on an exhaust system of a single cylinder diesel engine. Previous experimental investigations concerned the gas-borne noise characterization of the engine and an experimental campaign on the evaluation of the transmission loss factor of the tested exhaust system. Contemporarily, a 3D numerical model of the system has been created in order to obtain a validate tool able to predict the radiated noise in the environment. The created model represents a mixed FEM-BEM application. In addition, a CFD model has been created in order to better simulate the fluid flow pulsation and to calculate the flow interactions with the external skin of the muffler, too, in terms of structural vibrations. Based upon these information the radiated power has been evaluated on the FEM-BEM 3D model and then compared with the experimental data.

Over the last years, SEA has been recognized as a useful tool to model and analyze the high-frequency vibro-acoustic behavior of fully assembled complex structures. This paper discusses the experimental derivation of the loss factor model of a passenger car. The paper outlines the different steps which need to be taken to obtained a fully validated experimental SEA model. This includes the subdivision into subsystems, the PIM measurement campaign, the derivation of the loss factors and their associated confidence levels and the model validation. The paper further details how the experimental SEA model was used to quantify and investigate the airborne and structure-borne contributions to the interior noise level for a road noise test condition. The operational power inputs to the vehicle were indirectly determined from operational response measurements. A contribution analysis showed that airborne noise sources dominated structure-borne noise sources above 500Hz.