Large Eddy Simulation of Low Swirl Flames Under External Flow Excitations

Response of supercritical round jets to various excitation modes

“…The current numerical simulations are performed using a compressible solver developed in the OpenFOAM platform. The present authors have also successfully developed and verified some other solvers in the OpenFOAM platform (Shahsavari, Farshchi & Arabnejad 2017; Shahsavari & Farshchi 2018). Turbulence modelling is achieved by using LES.…”

“…Here, ‘V’, ‘H’, ‘F’, ‘VH’ and ‘VF’ stand for varicose, helical, flapping, dual varicose/helical and dual varicose/flapping mode excited cases, respectively. Previous studies showed that exciting subcritical jets with frequencies correspond to the most amplified hydrodynamic instabilities has the highest impacts on the jet features (Crow & Champagne 1971; Shahsavari & Farshchi 2018). In the present study, in order to capture the maximum effects of the excitations on the supercritical jet, the most amplified frequencies in the potential core (1116 Hz) and the transient region (341, 232 Hz) of the unexcited case are used to excite the jet.…”

Nonlinear combustion instability analysis of a bluff body burner based on the flame describing function

“…The motion of the grid-scale part that contains most of the energy has a major impact on the flow and can be solved directly by the governing equation; the motion of the sub-grid-scale part that cannot be directly solved is approximately isotropic, and small-scale pulsation affects the large-scale. The influence of motion requires the establishment of a mathematical model to simulate the non-closed term generated by the nonlinear term, so that the mesh-scale motion equation is closed and solvable, and the three-dimensional average N–S equation containing chemical reactions is as follows 27,29,30 where ρ is the density, P is the pressure, Y i is the mass fraction of the i th species, h s is the sensible enthalpy, Sc is the Schmidt number, and Pr is the Prandtl number. The heat release truetrueω˙k¯ and truetrueω˙T ¯ are the chemical reaction source terms of the component and energy, respectively.…”

“…Among them, the amplitude can reach 64% of the average test speed.

Figure 1.(a) Cambridge combustor; (b) sketch of the 3-D computational domain used. 27

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“…The motion of the grid-scale part that contains most of the energy has a major impact on the flow and can be solved directly by the governing equation; the motion of the sub-grid-scale part that cannot be directly solved is approximately isotropic, and small-scale pulsation affects the large-scale. The influence of motion requires the establishment of a mathematical model to simulate the non-closed term generated by the nonlinear term, so that the mesh-scale motion equation is closed and solvable, and the three-dimensional average N-S equation containing chemical reactions is as follows 27,29,30…”