Improved Techniques in Intake Acoustic System Modeling of a Supercharged Engine 2017-01-1790
Vehicle noise emission requirements are becoming more stringent each passing year. Pass-by noise requirement for passenger vehicles is now 74 dB (A) in some parts of the world. The common focus areas for noise treatment in the vehicle are primarily on three sub-systems i.e., engine compartment, exhaust systems and power train systems. Down- sizing and down- speeding of engines, without compromising on power output, has meant use of boosting technologies that have produced challenges in order to design low-noise intake systems which minimize losses and also meet today’s vehicle emission regulations. In a boosted system, there are a variety of potential noise sources in the intake system. Thus an understanding of the noise source strength in each component of the intake system is needed. One such boosting system consists of Turbo-Super configuration with various components, including an air box, supercharger, an outlet manifold, and an intercooler.
In the present work, full system level modeling is considered for dual boosting system of turbo-super configuration from an NVH perspective. The supercharger as one of the sources of intake noise was considered and noise radiation emanating from intake system was calculated. For this analysis, source impedance and strength of supercharger measured from testing are considered as inputs to the development of full system level model. There were challenges in modeling elements like the intercooler and the airbox which were addressed during development of this methodology. The system level noise prediction is presented through one way Fluid Structural Interaction (FSI) simulation. For this full system, structural FE model and duct model which is negative of the structural model is developed using acoustic FE in LMS Virtual Lab. The results are then compared with the test. This improved technique in intake acoustic modeling of a supercharged engine is useful for accurate identification and ranking of noise radiating components in the full system considered from engine inlet to air box filter.