Modelling of Acoustic Resonators Using the Linearized Navier Stokes Equations 2016-01-1821
To tune the acoustics of intake systems resonators are often used. A problem with this solution is that the performance of these resonators can be affected a lot by flow. First, for low frequencies (Strouhal-numbers) the acoustic induced vorticity across a resonator inlet opening will create damping, which can reduce the efficiency. Secondly, the vorticity across the opening can also change the end-correction (added mass) for the resonator, which can modify the resonance frequency. However, the largest problem that can occur is whistling. This happens since the vortex-sound interaction across a resonator opening for certain Strouhal-numbers will amplify incoming sound waves. A whistling can then be created if this amplified sound forms a feedback loop, e.g., via reflections from system boundaries or the resonator. To analyse this kind of problem it is necessary to have a model that allows for both sound and vorticity and their interaction. This means using a convected wave equation type of model is not sufficient. A better approach is to apply the linearized Navier Stokes equations, which will give a full model of the vortex-sound effects. In this paper an effort to apply this approach on a set of generic resonators is described. Besides the numerical results comparisons with experiments are also presented.
Citation: Du, L., Abom, M., Karlsson, M., and Knutsson, M., "Modelling of Acoustic Resonators Using the Linearized Navier Stokes Equations," SAE Technical Paper 2016-01-1821, 2016, https://doi.org/10.4271/2016-01-1821. Download Citation
Author(s):
Lin Du, Mats Abom, Mikael Karlsson, Magnus Knutsson
Affiliated:
KTH CCGEx, Volvo Car Group
Pages: 4
Event:
9th International Styrian Noise, Vibration & Harshness Congress: The European Automotive Noise Conference
ISSN:
0148-7191
e-ISSN:
2688-3627
Related Topics:
Acoustics
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