• Exhaust acoustic
• Flow acoustic
• Intake acoustic
• Pressure drop
• Transmission Loss

Noise and vibration of motor vehicles are increasingly important for the automotive industry. While noise pollution legislation is driving down vehicle exterior noise, customers are becoming more discerning in relation to noise inside the vehicle. Indeed, noise and vibration are now considered to be two of the most important quality factors in vehicle design.
For these reasons, since intake and exhaust systems play a fundamental role both in the environmental and interior noise emission of an engine vehicle, their acoustic design has gained more and more importance over the years. Furthermore, these systems must be designed also considering the fluid dynamic aspect since they strongly influence engine’s performances and efficiency.
Today, the fluid dynamic and acoustics properties of intake/exhaust components are often investigated separately. This thesis illustrates, with theoretical arguments and examples, that the presence of flow rate alters the acoustic behaviour of a component. It follows that testing simultaneously both these aspects is convenient in terms of accuracy, efficiency, cost, and time reduction.
After having identified the main sources of intake and exhaust noise and the components meant to control and attenuate this noise, the available simulation methods used to predict the acoustic silencers performances are reviewed, focusing on the possibility to account for the flow-acoustic interaction.
In this thesis, the design proposal of a flow-acoustic test rig which is capable of measuring both fluid dynamic and acoustic properties is carried out. Starting from the study of related literature and the definition of requirements, the bench layout and then its components have been identified. To support the test rig design process has been created a bench model with GT-Power which is a mono dimensional fluid-dynamic simulation software offering the possibility to perform fluid-acoustic simulations.
The interaction between the flow-acoustic test rig and the computer aided engineering (CAE) world is not limited to the design phase. When the flow-acoustic test rig will be completed, the experimental measurements, that fully characterize the tested component, could be used to create a CAE model of the component which could be tuned considering both the fluid dynamic and acoustic experimental data. Eventually, the obtained tuned model can then be simulated reproducing the real operating conditions, in terms of exhaust gas temperature and flow rate, and obtaining reliable results.
This design approach, based on a strong synergy between experimental test and simulation (both considering the flow rate), can surely be beneficial for intake and exhaust system design.

Noise and vibration of motor vehicles are increasingly important for the automotive industry. While noise pollution legislation is driving down vehicle exterior noise, customers are becoming more discerning in relation to noise inside the vehicle. Indeed, noise and vibration are now considered to be two of the most important quality factors in vehicle design. For these reasons, since intake and exhaust systems play a fundamental role both in the environmental and interior noise emission of an engine vehicle, their acoustic design has gained more and more importance over the years. Furthermore, these systems must be designed also considering the fluid dynamic aspect since they strongly influence engine’s performances and efficiency. Today, the fluid dynamic and acoustics properties of intake/exhaust components are often investigated separately. This thesis illustrates, with theoretical arguments and examples, that the presence of flow rate alters the acoustic behaviour of a component. It follows that testing simultaneously both these aspects is convenient in terms of accuracy, efficiency, cost, and time reduction. After having identified the main sources of intake and exhaust noise and the components meant to control and attenuate this noise, the available simulation methods used to predict the acoustic silencers performances are reviewed, focusing on the possibility to account for the flow-acoustic interaction. In this thesis, the design proposal of a flow-acoustic test rig which is capable of measuring both fluid dynamic and acoustic properties is carried out. Starting from the study of related literature and the definition of requirements, the bench layout and then its components have been identified. To support the test rig design process has been created a bench model with GT-Power which is a mono dimensional fluid-dynamic simulation software offering the possibility to perform fluid-acoustic simulations. The interaction between the flow-acoustic test rig and the computer aided engineering (CAE) world is not limited to the design phase. When the flow-acoustic test rig will be completed, the experimental measurements, that fully characterize the tested component, could be used to create a CAE model of the component which could be tuned considering both the fluid dynamic and acoustic experimental data. Eventually, the obtained tuned model can then be simulated reproducing the real operating conditions, in terms of exhaust gas temperature and flow rate, and obtaining reliable results. This design approach, based on a strong synergy between experimental test and simulation (both considering the flow rate), can surely be beneficial for intake and exhaust system design.