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ISSN Онлайн: 2642-0554

AN LES STUDY OF UNSTEADY FLOW EVOLUTION IN A SWIRL-STABILIZED INJECTOR WITH EXTERNAL EXCITATIONS

Shanwu Wang
Department of Mechanical and Nuclear Engineering The Pennsylvania State University University Park, PA 16802, USA

Shin-Yang Hsieh
Department of Mechanical and Nuclear Engineering The Pennsylvania State University University Park, PA 16802, USA

Vigor Yang
Department of Mechanical Engineering The Pennsylvania State University University Park, PA 16802, USA; School of Aerospace Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332, USA

Аннотация

The flow evolution and dynamic response of a gas-turbine swirl-stabilized injector to external forcing were investigated using a large-eddy-simulation (LES) technique. The formulation included the complete conservation equations of mass, momentum, and energy in three dimensions. The numerical scheme employed a density-based, finite-volume approach with explicit time marching. A multi-block technique in conjunction with domain decomposition was implemented to parallelize the code. The analysis was first conducted for conditions without external excitations to investigate the internal flow evolution in the injector. Periodical oscillations of the mass flow rate were then imposed at the injector inlet to characterize the injector dynamics over a broad range of frequency. Results indicated that external forcing only exerts minor influences on the mean flow properties due to the broadband characteristics of the injector flow. The dynamic response of the injector, however, depends significantly on the forcing frequency in terms of the acoustic admittance and the mass transfer functions. Energy can be transferred among the various structures in the flowfield under external excitations, consequently causing highly non-uniform distributions of the oscillatory flow properties at the injector outlet. Information of this kind can be effectively used to characterize gas-turbine combustion instability.