• Combustion Instabilities Absorber Tangential Rocke

This master thesis describes the results of the work developedas part of the high frequency combustion instability research program at the Institute for Space Propulsion of the German Aerospace Center located in Lampoldshausen (Deutsches Zentrum für Luft und Raumfahrt, DLR).The intention of this work is to conductan analytical investigationto getdetailed insightof the dynamics of the first tangential eigenmode in a cylindrical combustion chamber with a cavity tuned to a quarter wave absorber.After a brief introduction and an explanation of general outlines about the investigation methods, an overview of literature is given paying attention to the solution of the three dimensional waveequation.In the following section the results of a specific test campaign, named DLR-BKD-LL-11, previously conducted at the P8 test facility are presented.Afterwards, a systematic analysis of the mathematical problem representative of the behaviour of the first tangential (1T) mode in an ideal cylindricalcombustor without any absorber is performed.Thereafter the influence of an acoustic cavity coupled with the combustion chamberis evaluated. Additional hypothesis are made and a newmodel isdeveloped and implemented in MATLABin order to obtain anagreement between the experimental and the theoretical data.In order to further validatethe mathematical model, a numerical reconstruction procedure of the acoustical 1T mode is realized. Thefinal goal is to confirm that the developed model effectively describes some important aspects of the real acoustic pressure field.