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)

Counterflow


A fundamental pre-requisite for the establishment of predictive full-scale simulations tools for combustion systems is the development of reduced chemical models able to capture the most significant aspects of the combustion processes such as flame extinction or pollutants formation. As a basic step, this reduction process requires a fundamental understanding of the detailed chemistry of a flame which must be supported by experimental evidence.

Counterflow laboratory flames are excellent candidate to explore combustion chemistry. because they can be simulated with reduced computational efforts. For this reason, the overall setup is designed to produce the same velocity and scalar fields described mathematically by the similarity solution implemented in several 1D codes.


Design features

The counterflow setup consists of two vertically opposed ducts to separately introduce air and fuel. The opposed flows form a stagnation plane. The flame is aerodynamically stabilized between the nozzles close to the stagnation plane, hence heat losses of the flame towards the nozzles are typically negligible. In order to minimize disturbances of the flame by environmental effects, the opposed flows are shrouded by a shielding flow of inert gas. The shielding flow is introduced through an annular gap surrounding each of the nozzles. The hot product gases of the flame emerged the well-controlled flow region between the nozzles in radial direction to the outside.

The mass flow rates are automatically controlled by mass flow controllers. For liquid fuel investigations, the setup is equipped with a vaporizer system and heated lines to avoid condensation of the vaporized fuel.


Experimental methods

The ITV employs two counterflow burner setups to investigate the soot formation of advanced bio-derived fuels and to shed light into combustion processes of coal volatiles under air and oxy-fuel conditions. Detailed characterization of the combustion chemistry is performed via a time-of-flight (ToF) mass spectrometer measurements which allow for a fast identification of stable and unstable species in the flame. Furthermore, optical laser-based diagnostics, such as laser-induced incandescence and laser extinction, are used to determine the soot volume fraction within the flame.