Passive scalar interface in a spatially evolving mixing layer (A. Attili and D. Denker)

Quartz nozzle sampling (D. Felsmann)

Dissipation element analysis of a planar diffusion flame (D. Denker)

Turbulent/non-turbulent interface in a temporally evolving jet (D. Denker)

Dissipation elements crossing a flame front (D. Denker and B. Hentschel)

Particle laden flow (E. Varea)

Turbulent flame surface in non-premixed methane jet flame (D. Denker)

DNS of primary break up (M. Bode)

Diffusion flame in a slot Bunsen burner (S. Kruse)

Various quantities in spatially evolving jet diffusion flame (D. Denker)

Flame Quenching at Cold Walls


Basics

In technical applications it is often not possible or desirable to allow for a large separation between flames and the surrounding walls. In these cases, interaction between flame and wall can occur. The most obvious of these interactions is quenching of the flame due to high heat losses to the cold wall. The combustion process is disrupted, leading to large local concentrations of unburnt hydrocarbons and carbon monoxide close to the wall. Additionally, the downstream oxidation of hydrocarbons and carbon monoxide is slowed, due to the overall decreased temperatures along the wall. The rate of oxidation of these pollutants is controlled by diffusive transport towards the hot gases, partly because convective transport is diminished by the vicinity to the wall.


Methods

In order to accurately predict emission concentrations and distributions improvements to current combustion models are necessary. Direct numerical simulations are performed to gain insight into the chemical and diffusive processes close to the wall and the influence of the interaction with the flame. Models are derived from the DNS analysis and implemented in large eddy simulations. The inclusion of DNS and LES allows for a detailed investigation of the fundamental processes and for validation with experimental results and simulations on a system scale that is relevant to applications. Several aspects such influence of wall temperature, pressure, choice of fuel and modelling of diffusive fluxes are investigated.