Fields of application of silencers and mufflers

Examples for the wide range of applications of mufflers are:

• combustion engines, e.g. in
  • road and rail vehicles
  • chain saws, lawn mowers
  • emergency power supplies, cogeneration units
  • vacuum cleaners, leaf blowers
• power plant facilities

• turbo chargers for diesel engines of ships

Classification of silencers and mufflers

Mufflers can be characterized and classified in various manners. One possibility is the classification in passive, active and hybrid mufflers, depending on their working principle.

Passive mufflers are named by the fact, that only passive elements, e.g. sound absorbing materials and changing cross sections in the duct achieve the sound attenuation. In contrast to that, active mufflers (active noise control, ANC) are based on the application of additional sound sources, that are supposed to prevent the propagation of noise by interference.

The effect of hybrid mufflers is caused by a combination of both working principles. Classifications with respect to the design, e.g. baffle silencer, are also commonly used.

Design and optimization of silencers and mufflers

Emphasis of our services are the design, the calculation and the optimization of locally-absorbent und laterally-absorbent, passive mufflers. In cooperation with the Fraunhofer Institut für Fertigungstechnik und Angewandte Materialforschung, for instance, we apply hollow metal sphere structures as self-supporting sound absorbers being potentially suitable to mufflers.

For the design various analystical models (see AED 8001 – AcoustiCalc^{® Silencer}) and numerical calculations are applied (see FEM).

The innovative measuring system AED 1400 – AcoustiTube^{® HighTemp} allows the measurement of the transmission loss of mufflers in situ for temperatures up to 600°C. The measurement results can be processed further using the software AED 8001 – AcoustiCalc^{® Silencer}, e.g. to calculate the effectiveness of a complete exhaustion system.

Furthermore, the available measuring equipment and specially developed test benches allow the determination of the insertion loss of mufflers in situ and in the laboratory according to DIN EN ISO 7235, DIN EN ISO 11820 and DIN EN ISO 11691.