Fast prediction of noise level and air flow in rail vehicle HVAC ducts using a Modelica framework

Design limits often let the manufacturer of HVAC systems for rail vehicles face the challenge in meeting the strict noise level limit as well as insuring the required air flow. We introduce a framework for fast joint calculation of acoustic and flow quantities in HVAC duct networks which is designed for concept modelling in an early construction stage. The acoustic domain is described by the band averaged sound power approach proposed in the VDI and ASHRAE guidelines, the fluid mechanic domain by pressure loss models. Flow-acoustic interaction is taken into account. Based on the object-oriented, equation based multi-domain modelling language Modelica the framework can be integrated into already existing Modelica libraries for various physical domains and is easily extendable. User-friendly simulation-setup in a GUI and external parameterization ensures persistent data management and a smooth workflow.