Impact of acoustic forcing on soot evolution and temperature in ethylene-air flames

Combustion instability mitigation by magnetic fields

“…Still the computed and measured oscillation frequencies are very close at 15.6 Hz and 12.6 Hz, respectively. Furthermore, as in [27], the changes of the peak soot volume fraction in the wings of the oscillating flame can be reproduced numerically. Figure 2 displays in the left-most four images the measured (a) and computed (b) soot volume fraction fields for one oscillation cycle without magnetic field.…”

“…In the following paragraph, the two-dimensional, axisymmetric, numerical setup, and the applied methods to reproduce the experimentally observed stabilization process are outlined. The parallelized, finite difference code CIAO solves the Navier-Stokes equations in the low Mach number limit, utilizing spatial and temporal staggering, together with Crank-Nicolson type time advancement [26,27]. The Poisson equation for pressure is solved by the multi-grid HYPRE solver and the scalar equations are solved via the bounded quadratic upstream interpolation for convective kinematics (BQUICK) scheme, based on the QUICK scheme of Leonard [28].…”

“…The number of cycles needed to ensure a fully periodic state was identified by a start-up transient analysis [37]. The here employed numerical methods and soot formation models have been validated in an earlier paper [27] by comparing a steady ethylene flame burning in a coflow stream of air to color-ratio pyrometry and laser induced incandescence measurements from two different laboratories. The soot formation and oxidation zones have been well predicted as well as the location and the magnitude of the peak soot volume fraction.…”

“…The soot formation and oxidation zones have been well predicted as well as the location and the magnitude of the peak soot volume fraction. The impact of flame oscillations on the soot predictions was investigated in the same paper [27] by pulsing the described steady coflow flame at two frequencies. Again, the trends were predicted really well.…”

Multi-diagnostic soot measurements in a laminar diffusion flame to assess the ISF database consistency

“…This configuration is also widely used to validate soot models for laminar configurations [7,10]. However, the validation procedure requires a consistent database and estimated uncertainties, reduced to the lowest possible level by comparing different diagnostics.…”