Acoustic Analysis of Ventilation Systems

The Forschungsvereinigung für Luft- und Trocknungstechnik e.V. (FLT) (registered research association for air and drying engineering) promoted the research project "Acoustic Design and Analysis of Ventilation and Air-Conditioning Systems" (AiF-Nr. 11121) with the help of the Arbeitsgemeinschaft industrieller Forschungseinrichtungen e.V. (AiF) (working committee of registered industrial research associations) and financed by funds of the Bundesministerium für Wirtschaft (German Federal Ministry of Economic Affairs).

Within the context of this research project, components of ventilation and air-conditioning systems were investigated with regard to the acoustic effect and interaction at low frequencies. It was possible to prove how resonances are developed in a duct system and what kind of components generate and influence these resonaces. Calculation methods were developed for the determination of attenuation, sound level and impedance at selected positions in the duct system and in adjacent rooms.

The conversion was effected by a computer program running under Windows95 or higher. The program has a user-friendly surface, which presents the duct system in graphs, as well as an integrated help for a simple access to all calculation parameters and the handling of the program. Integrated measuring modules allow measurements by means of the program and an indirect comparison with the calculations.

The program is suited for the dimensioning of new systems and for the analysis of already existing systems at low frequencies with high frequency resolution. The program allows the detection of disturbing resonances as well as an optimization by means of system modifications, resulting in a greater acoustic safety in operation of the system at low frequencies.

This research project was worked on at the Fraunhofer-Institute of Building Physics IBP in Stuttgart from March, 1997 to August, 1998. For further information please contact FLT e.V. in Frankfurt by Fax.-No. 069/66 03-12 18.