Resabtors - Reducing fan and flow noise in HVAC applications

A profound knowledgebase exists for the design, simulation and production of resonators for the charged air side of combustion engines. Based on this knowledge, a new generation of multi-material mufflers was developed for clean air applications, such as fan and flow noise attenuation in HVAC systems. New materials like "special treated foams" are used in combination with a resonator. Such parts are named "Resabtors" to account for the different noise attenuation principles Resonation (tonal) and Absorption (broad-band). As installation space is always limited, these two principles were highly integrated into one component. This integration, however, called for new experimental and simulation methods for precise prediction of the noise attenuation level of the Resabtors. Such methods were not existing when starting this development; but finally, the challenges could be solved. A development environment for a fast and precise Resabtor design has been established and will be presented. Like all sound absorbers placed in a flow, Resabtors can also produce unwanted flow-induced noise. When exposed to a noise containing flow stream, the noise cancellation by the Resabtor must by far outperform the noise induction due to the flow. This was achieved in a Resabtor HVAC duct application and will be presented.