Aim
High-pressure combustion reactions are common in practical applications like internal combustion engines, gas turbines in power plants or jet-propulsion engines. Due to the fact that these systems are highly complex and in case of the combustion in engines they are even unsteady, it is difficult to study fundamental processes. in a premixed burner, a steady high pressure flame provides the possibility to specifically address certain conditions while all the other parameters stay constant. The mean research topic at this facility is the study of soot formation as a function of the pressure in high pressure flames and to study the influence on pressure on soot measurement techniques, such as laser-induced incandescence (LII). For this, additional measurements based on absorption spectroscopy or angle-resolved scattering are possible. The burner is designed for operating pressures up to 40 bar.

Approach
The high-pressure burner consists of three concentric porous metal plates that feed gas mixtures of different composition into the burner housing. The inner burner (supplied with C₂H₄+ air, rich, premixed) generates the sooting flame of interest. It is surrounded by a burner (supplied with CH₄ + air, stoichiometric, premixed) to stabilize the inner flame with minimal thermodynamic, reactive or optical influence. Around the surrounding flame a flow of air shields the hot combustion gases from the walls and the windows. Optical access is provided via four windows (at 90° to each other) at the side of the burner. Soot particles are heated to incandescent temperatures by a pulsed Nd:YAG laser (1064 nm). The detection of the incandescence takes place via fast photomultipliers (rise time 0.8 ns) at two different wavelengths, which gives also the possibility to determine the temperatures of the laser-heated soot particles via two-color pyrometry. From the variation in light emission during the cooling period of the laser-heated particles information about particle sizes is gained.

References
M. Hofmann, W. G. Bessler, C. Schulz, H. Jander, "Laser-induced incandescence (LII) for soot diagnostics at high pressure," Appl. Opt. 42, 2052-2062 (2003).

Contact
Dr. T. Endres, Torsten Endres , Tel +49 203 379 3505, IVG