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)

OH layer in a turbulent wall bounded flame (K. Niemietz)

Soot formation of conventional and alternative fuels

Motivation

Soot is formed during the combustion under oxygen deficient conditions. Soot formation is one of the most complex processes in the combustion research field, which covers homogeneous and heterogenoues chemical reactions and is strongly coupled with the local flow field and the ambient pressure. In addition, soot formation is sensitive to the molecular structure of the fuel which has a major impact on the formation of soot precursors.

Soot has been identified to have tremendous adverse effects of human health and to contribute to global warming. Hence, legislative regulations aim to limit the soot emission. In order to meet the challenging emission limits and design efficient combustion systems, predictive simulations become an important tool. In this context, it is essential, that models accurately predict the complex processes of soot formation. To develope and validate these models, experimental data of soot precursors and soot parameters are urgently required.

Methods

In order to gain detail insights into soot formation and provide comprehensive data sets, multiple experimental techniques are used to investigate reference flames. Measurements are performed in laminar counterflow flames, which are characterized by well-defined boundary conditions. In addition, A onedimensional similarity solution exists, which significantly reduces the numerical effort to compute counterflow flames and makes the counterflow setup a valuable simulation target. The employed techniques cover laser-based techniques as well as sophisticated probing techniques. The soot volume fraction is determined by laser-induced incandescence (LII) which has been optimized in this project for applications to counterflow flames [1]. Advanced probing techniques, such as Time-of-Flight mass spectrometry and GC/MS, provide information on soot precursors. A scanning-mobility-particle-sizer (SMPS) yields local distributions of the soot particle size.

Results

First results of soot measurements in counterflow flames fuel with conventional fuel components emphasize the demand for further model improvement. In particular, the prediction of soot precusors shows significant potential for improvement [2]. In future, the focus of this project lies on the investigation of the soot production of alternative fuels, such as bio-hybrid fuels, which have been found to differ significantly in the soot formration processes as compared to conventional fuels.

References

[1] S. Kruse, P. Medwell, J. Beeckmann, H. Pitsch, The significance of beam steering on laser-induced incandescence measurements in laminar counterflow flames. Applied Physics B-Lasers And Optics, vol. 124 no. 212, 2018. [DOI]

[2] Stephan Kruse, Achim Wick, Paul Medwell, Antonio Attili, Joachim Beeckmann and Heinz Pitsch. Experimental and numerical study of soot formation in counterflow diffusion flames of gasoline surrogate components. Combustion and Flame, vol. 210, pages 159-171, DEC 2019. [DOI]