Host Institution: Technische Universität Darmstadt (Germany)
Department of Reactive Flows and Diagnostics
Phone: +49 6151 16-28897
Fax: +49 6151 16-28900
I’m devoted to the study of practical combustion systems, typically operating in a fuel stratified mode. One unsolved issue in combustion modeling is the treatment of fuel stratified flames that might switch from premixed to non-premixed mode. The development of new modeling strategies and validation of such innovative models needs benchmark flames.
For this purpose, the understanding of both physical and chemical processes, such as mixing, flow field and reaction progress, is crucial. The key to understand these processes is the simultaneous measurement of several quantities. Modern laser based diagnostics allow an accurate measurement of several physical variables with high temporal and spatial resolution without affecting the original flow field in any way. 2D Particle Image Velocimetry (PIV) is used to resolve the flow field, as well as Acetone Laser Induced Fluorescence (LIF) is implemented, at this stage, for a better understanding of the mixing process. Experimental activities, whose aim is providing data for simulations validation, are coupled with intense post processing stages, aimed at a precise characterization of the observed systems.
Project title: Experimental investigations under differ¬ent thermal efficiencies and practical engineering conditions using advanced Laser Diagnostics
Objectives. Practical combustion systems typically are operating in a fuel stratified mode. One unsolved issue in combustion modeling is the treatment of fuel stratified flames that might switch from premixed to non-premixed mode. For developing new modeling strategies and validation of such innovative models benchmark flames are urgently needed. For this purpose at TUDA a series of turbulent fuel stratified target flames has been investigated. For providing well-defined boundary conditions the nozzle is made from annular slots. A central pilot flame is used to anchor the flame such that operation at high Reynolds-numbers is possible. For selected flames the thermo-kinetic states have been investigated by means of Raman/Rayleigh scattering, including information on temperature and main chemical species concentrations. In a next step pollutants such as NO concentrations must be quantified that cannot be easily tabulated on reaction progress variables. Due to low concentrations more sensitive diagnostics such as laser-induced fluorescence (LIF) must be used.
Expected results. In this project simultaneous temperature and NO concentration measurement are planned. Temperatures are measured either by Rayleigh scattering or by coherent anti-Stokes Raman scattering (CARS). Temperature is needed as measure of reaction progress and for density/quenching corrections for NO-LIF measurements. NO is excited in its A-X-transition around 226 nm and detected red-shifted. The new data are combined with previous measurements of velocities and main species concentration to provide a unique benchmark for combustion modeling including pollutant formation.
Planned secondment. FR-CS (8-10 months). Data post processing and involvement to validation of numerical simulations.