Conference article

SoundDuctFlow; a Modelica library for the joint calculation of acoustic and flow quantities in HVAC (Heating; Ventilation and Air Conditioning) ducts is presented. Modeling the sound propagation in ducts by one dimensional acoustic twoport methods is a well-established technique for the acoustic characterization of large HVAC duct networks. Two different approaches of acoustic modeling will be considered in the framework: When resonant phenomena are insignificant; it is often sufficient to apply band-averaged models to predict the sound power level and the transmission loss within the individual components of the duct network. For the low frequency range where linear plane wave propagation is valid; acoustic two and multi-port models based on a transmission matrix formulation of the sound pressure can be applied for high frequency resolution and phase accurate calculations. For the prediction of the mean air flow in the duct network pressure loss models are applied. The coupling of acoustic and flow elements permits the simulation of flow acoustic phenomena.

For setting up large networks a smooth work flow is vital for the user: The simulation is easily set up using the GUI provided by Dymola. External parameterisation ensures persistent data management. The resulting system of equations is automatically pre-processed and solved by Dymola.

In this paper an overview of this new library is given together with exemplary applications.

Acoustics; flow; ducts; flow noise; HVAC; modeling; simulation; Modelica library