Fraunhofer Institute for Building Physics IBP
The program performs calculations based on the theory of sound propagation in lined absorbent ducts with superimposed flow:
- Propagation loss Lp in the splitter airway passage of width 2s and length Lk
- Reflection loss Lr at the splitter entry and exit
The sum of these two attenuation parts results in insertion loss Li of the silencer as it is measured on the test stand according to EN ISO 7235. The theoretical propagation loss of long silencers is generally not achievable in practice due to the stimulation, propagation and radiation of structure borne noise in the splitters. This influence is accounted for by an empirical correction Lp* on the calculated propagation loss. The influence of superimposed flow and temperature on the propagation loss is taken into account in the program’s calculations. The program also calculates the pressure loss and the sound power of the flow noise as well as the energy costs incurred by the silencer. The integrated design tool makes it easy to determine the geometry of the silencer taking into account duct cross-section and volume flow.