AERODYNAMIC SUPPRESSION OF COMBUSTION-DRIVEN PRESSURE OSCILLATIONS IN TECHNICAL PREMTXED COMBUSTORS

In recent studies on feedback mechanisms leading to the formation and the sustainment of large amplitude pressure oscillations in industrial combustors (e.g. gasturbine combustors, industrial furnaces, etc.) by amplification of initially small-amplitude disturbances the interests are more and more focused on the periodical formation and combustion of coherent turbulent ring vortex structures, being an important characteristic of periodically modulated flows [1,2,3]. On one side, these structures are mainly responsible for the amplification of small-amplitude disturbances, while forming and combusting in-phase with the pressure oscillation in the combustion chamber, fulfilling Rayleigh's criterion. On the other side they make possible to control the amplitudes of combustion-driven pressure oscillations by aerodynamic means (secondary air injection), that can avoid the formation of reactive vortex structures and therefore, interrupt the feedback coupling between pressure oscillation, periodic flow field and periodic heat release. In the present paper experimental studies on the fluiddynamical conditions for the formation of coherent ring vortices are shown and furthermore, first test results of a new method for the suppression of large-amplitude pressure oscillations, driven by periodic ring vortex combustion, are presented, obtained from power plant gasturbine combustors.