Vortical flow dynamics and acoustic response of swirl-stabilized injector

This present work describes a comprehensive numerical study of the transient flow dynamics of a single-element swirl-stabilized injector. The theoretical model is based on the complete conservation equations of mass, momentum, and energy in three dimensions. Turbulence closure is achieved by means of a large-eddy-simulation (LES) technique. The compressible version of the Smagorinsky eddy-viscosity model is employed to describe the subgrid-scale turbulent motions and their effect on large-scale structures. The governing equations and the associated boundary conditions are solved by a finite-volume, four-stage Runge-Kutta scheme along with the implementation of the message passing interface (MPI) parallel computing architecture. Results show that the flow field in the injector is intrinsically unsteady and subject to shear and centrifugal instabilities. The unsteady local flow motions and vortex breakdown are clearly visualized and explained on theoretical bases. The unsteadiness may be related to periodic vortex shedding, vortex breakdown, and other phenomena that are velocity sensitive. Several mechanisms responsible for driving instabilities have been identified and quantified.