Experimental characterization of the spatiotemporal dynamics of a turbulent flame in a gas turbine model combustor using computed tomography of chemiluminescence

An experimental study was conducted based on the recently available computed tomography of chemiluminescence (CTC) technique with a swirl-stabilized gas turbine model combustor to obtain both time-resolved and three-dimensional (3D) dynamics of the turbulent flame in confined situation. The CTC system employed in the present study was designed in a cost-effective, but highly-efficient manner, which allows simultaneous recordings of six projections of the target flame with three cameras at a repetition rate of 1 kHz. Instantaneous flame topologies were successfully captured and highly-transient flame dynamics in the combustion chamber, such as local extinction and flame shape variations were also observed. A further analysis based on the instantaneous and phase-averaged 3D movements of the flame centroids suggested that the flame in the present combustor exhibited a helical but relatively stochastic propagation and a distinct azimuthal rotation around the combustor, which is in the direction of rotation imposed by the swirler to the flow. Results obtained in this work demonstrate the capability of the CTC technique to resolve the detailed spatiotemporal dynamics of turbulent flames in confined combustion systems, which is expected to be particularly helpful for the study of combustion instabilities, such as periodic combustion oscillations in fuel-lean gas turbine engines.