Unsteady flow evolution in swirl injector with radial entry. I. Stationary conditions

Abstract

The vortical flow dynamics in a gas-turbine swirl injector were investigated by means of large eddy simulations. The flow enters the injector through three sets of radial-entry, counter-rotating swirl vanes. The formulation treats the Favre-filtered conservation equations in three dimensions along with a subgrid-scale model, and is solved numerically using a density-based, finite-volume approach with explicit time marching. Several methods, including proper orthogonal decomposition, spectral analysis, and flow visualization, are implemented to explore the flow dynamics in the complex three-dimensional flowfields. Various underlying mechanisms dictating the flow evolution, such as vortex breakdown, the Kelvin–Helmholtz instability, and helical instability, as well as their interactions, are studied for different swirl numbers. The flowfield exhibits well-organized motion in a low swirl-number case, in which the vortex shedding arising from shear instabilities downstream of the guide vanes drives acoustic oscillations of the mixed first tangential and first radial mode. The flowfield, however, becomes much more complicated at high swirl numbers, with each sub-regime dominated by different structures and frequency contents.

Simulation of spray combustion in a lean-direct injection combustor

“…The PVC structure originates from the injector region and maintains its coherence till just downstream of the dump plane and partially wraps around the VBB. There is good qualitative agreement with past LES studies of premixed [25] and gaseous non-premixed [26] gas turbine combustors.…”

Dynamics and stability of lean-premixed swirl-stabilized combustion

“…A positive pressure gradient is generated along the axial axis, which consequently leads to the formation of a recirculation zone, providing the swirl strength is high enough. Wang et al [85,108] performed an LES study of unsteady flow evolution in the radial-entry swirl injector shown in Fig. 10.…”

“…Fig. 10 shows a typical radial-entry swirl injector [84,85], which consists of a mixing duct and a fuel nozzle located coaxially at the head end. Three radial-entry swirlers, counter-rotating with each other, are located at the entrance.…”

Large Eddy Simulations of gaseous flames in gas turbine combustion chambers

“…Two swirled flows (Fig. 22(b) & (c)) were investigated by LES [242,243] to assess flow dynamics and more specifically the position and breakdown of the IRZ as discussed in details in [244]. A second example is shown on Fig.…”