Development and Characterization of Porous Ceramic Absorbers for Damping of Thermoacoustic Instabilities

This work presents a new approach for the damping of thermoacoustic instabilities. The use of porous ceramics with high sound absorbent capabilities as lining in combustion chambers was studied in order to suppress self induced combustion instabilities by dissipate a significant part of the occurring sound power in the combustor. For that purpose a new processing technique to fabricate ceramics with a highly opened-pored structure having high sound absorption capabilities was developed by combining the freeze gelation process with sacrificial templating. Additionally, the acoustic properties of the material were characterized by measurements and simulations to describe its acoustic behavior in machine-oriented environment. The investigations indicates that the use of sound absorbent porous material has the potential to suppress thermoacoustic instabilities and it is due to an increase of the stable operating range of lean premixed combustion processes