Session: 04-19 Combustor Design I

Paper Number: 122648

122648 - Experimental Design Validation of a Swirl-Stabilized Burner With Fluidically Variable Swirl Number 

Swirling flows are widely employed for the stabilization of flames within gas turbine combustors, which are therefore equipped with suitable swirlers. The magnitude of the resulting swirl, i.e., a defined air rotation, is fixed by the swirler geometry. The induced swirl is found to be a parameter that significantly influences the flame stability and its dynamics. Thus, the possibility of active and continuous swirl variation is advantageous and of great importance for the assessment (and possibly control) of thermoacoustic instabilities, especially for the stable combustion of hydrogen or hydrogen-enriched fuels, for which new technological solutions are sought due to hydrogen’s high flammability. Although systems exist in which the degree of swirl can be mechanically varied, the existence of systems in which the degree of swirl can be dynamically adjusted without the need of mechanically moving parts is not known to the authors.

In this work, the experimental characterization of a swirl-stabilized burner that allows for the variation of the achieved swirl number via fluidic actuation is presented. The incorporation of such systems allows for an azimuthal direction change of the flow entering the swirler, solely depending on the injected secondary air flow, hence resulting in a linearly variable degree of swirl. The tested design, which relies on fluidic thrust vectoring systems known in the field of aerospace engineering, had been validated with numerical simulations in a previous study. In addition to the experimental validation of the working principle of the novel design and its swirl-variation performance, the experimental validation presented in this study allows for an accurate quantitative assessment.

To experimentally assess the flow field stabilized by the variable swirler, the axial, radial, and azimuthal velocity components in various regions of interest within the swirler and respective mixing tube are determined by means of laser-optical measurement techniques. The experimental data is processed and computed into swirl-numbers in order to quantify the degree of swirl as a function of the fluidic actuation. Then, the experimental focus is extended to a volume resembling a combustion chamber downstream of the burner’s mixing tube. Here, the resulting flow field is experimentally investigated in order to provide data which can be used for a quantitative flow-field comparison to state-of-the-art swirl-stabilized burners.

Our investigation paves the way to systems that allow for an active, dynamic, and continuous swirl variation without the need of moving parts. Novel fuel-flexible burner systems could then be realized which operate from pure jet flames to fully swirl stabilized flames, depending on the available fuel blend. Moreover, the stability and dynamics of flames and especially the influence of swirl thereon can be further assessed. As a result, the further development of the proposed system and, eventually, its application can significantly contribute to the decarbonization of the fossil energy sector.

Presenting Author: Mattias E. G. Eck Technische Universität Berlin

Presenting Author Biography: Mattias Eck is a Ph.D. student and research assistant at the Chair of Fluid Dynamics at the Technische Universität Berlin (TU Berlin). Within the HYPOTHESis project, his work focuses on the experimental assessment of flame dynamics, stability, and emissions in gas turbine combustors, with special emphasis on hydrogen combustion. In this respect, he is currently working on the development of a swirl-stabilized combustor, allowing for an actively variable degree of swirl, aiming at facilitating the experimental investigation of mechanisms affecting flame stability, dynamics, and emissions.
He graduated in Aerospace Engineering at the TU Berlin in 2021. Among other topics, his studies touched topics as for instance aerodynamics, thermodynamics, and aircraft propulsion systems.

Authors:

Mattias E. G. Eck Technische Universität Berlin
Philipp Zur Nedden Technische Universität Berlin
Jakob G. R. Von Saldern Technische Universität Berlin
Christoph Peisdersky Technische Universität Berlin, Chair of Fluid Dynamics
Alessandro Orchini Technische Universität Berlin
Christian Oliver Paschereit Technische Universität Berlin