MVP-Workshop Contribution: Modeling of Volvo bluff body flame experiment

Abstract

The Volvo burner features the canonical configuration of a bluff-body stabilized premixed flame. This configuration was studied experimentally under the Volvo Flygmotor AB program. Two cases are considered in this study: a non-reacting case with an inlet flow speed of 16.6 m/s and a reacting case with equilibrium ratio of 0.65 and inflow speed of 17.3 m/s. The characteristic vortex shedding in the wake behind the bluff body is present in the non-reacting case, while two oscillation modes are intermittently present in the reacting case. A series of large-eddy simulations are performed on this configuration using two solvers, one using a high-resolution finite-volume (FV) scheme and the other featuring a high-order discontinuous-Galerkin (DG) discretization. The FV calculations are conducted on hexahedral meshes with three different resolution (4mm, 2mm, and 1mm). The DG calculations are performed using two different polynomial orders on the same tetrahedral mesh. For the non-reacting cases, good agreement with respect to the experimental data is achieved by both solvers at high numerical resolution. The reacting cases are calculated using a two-step global mechanism in combination with the thickened-flame model. Reasonable agreement with experiments is obtained by both solvers at higher resolution. Models for combustion-turbulence interaction are necessary for the reacting case as it contains the length scale of the flame, which is smaller than the grid resolution in all calculations. The impact of such models on the flame stability and flow/flame dynamics is the subject of future research.

Subgrid Reaction-Diffusion Closure for Large Eddy Simulations Using the Linear-Eddy Model

“…4 in Giacomazzi et al [72], Cocks et al [73], and perhaps also Baudoin et al [74]). This latter predominantly symmetric shape appears to be the physically correct one for the present boundary conditions because many of the most recent simulation studies show this shape [75][76][77][78][79]. The cause for the transition from symmetric to asymmetric flame shape seen in the present simulations may be the use of a low-Mach-number formulation instead of a fully-compressible one [77].…”

Numerical analysis on mixing processes for transcritical real-fluid simulations

“…The unstructured solver, CharLES x , is employed in this study [48,49]. A finite volume approach is utilized for the discretization of the system of equations, Eq.…”

Requirements Towards Predictive Simulations of Turbulent Combustion

“…Theory and recent computational results have shown that for turbulent flows at low and moderate Mach numbers, an increase in polynomial order ( -refinement) is more effective in capturing turbulence characteristics, while for highly compressible turbulence regimes, ℎ-refinement becomes beneficial for representing shows and flow-discontinuities. Significant progress has been made on extending DG-methods for reacting turbulent flows [60][61][62][63]. However, in order to fully utilize the potential of these high-order variational methods for simulating turbulent flows [64][65][66][67], open research issues remain regarding the formulation of stabilization techniques, the development of combustion-physical models, and the construction of subgrid-closures that are consistent with the high-order discretization for large-eddy simulations.…”