Experimental investigation of the interaction of unsteady flow with combustion

In order to reduce the dimensions of the combustor swirl stabilized flames are used in heavy duty gas turbines. In our recent investigation of the swirling flow at a single heavy duty gas turbine burner under nonreacting conditions typical instabilities like precessing vortex cores and vortex shedding have been found (Schildmacher et al., Proceedings of the 6th European Conference on Industrial Furnaces and Boilers). In the present paper the experimental investigations will be discussed. Combustion instabilities have been analyzed by phase-locked laser doppler anemometer measurements. For the reacting flow, also combustion instabilities could be detected. The amplitude increases strongly with the equivalence ratio. The frequency of the oscillations for reacting conditions has been found to be slightly shifted towards lower frequencies compared to those of the corresponding nonreacting flow. In addition, for the reacting flow a linear and nonlinear range of oscillations could be discriminated.