アプリケーションギャラリ

Helmholtz resonators are used in exhaust systems, as they can attenuate a specific narrow frequency band. The presence of a flow in the system alters the acoustic properties of the resonator and the transmission loss of the subsystem. In this tutorial model, a Helmholtz resonator is located as a side branch to a main duct. The transmission loss through the main duct is investigated when a flow is introduced.

The mean flow is calculated with the SST turbulence model for Ma = 0.05 and Ma = 0.1. The acoustics problem is then solved using the Linearized Navier-Stokes, Frequency Domain (LNS) interface. The mean flow velocity, pressure, and turbulent viscosity are coupled to the LNS model. Results are compared to measurements found in a journal paper and the amplitudes and resonance locations show good agreement with the measurement data (as seen in the 1D plot). The balance between attenuation and flow effects needs to be modeled rigorously in order for the resonance location to be correct.