Computational Aero-acoustics Simulation of Whistle Noise in An Automotive Air-Intake System

Minor geometric features in the intake manifold airflow path with side-branch cavities are often responsible for unusual noise due to the complex air flow structure and its interaction with the internal acoustic field. Although airflow bench tests are faster to evaluate various alternate design geometries, understanding the mechanism of such noise generation is necessary for developing an effective design. A 2D computational fluid dynamics (CFD) simulation was performed on a baseline geometry, which produced a distinct whistle, and on a modified geometry, which suppressed the whistle. These 2D models were able to simulate the flow-acoustic coupling responsible for the whistle generation and hence clearly predicted the presence or the absence of a distinct whistle peak as observed in the experimental measurements. The results from the CFD simulations are compared in detail with that of the experiments and qualitative insights pertaining to the mechanism of whistle generation and suppression are developed.