Massachusetts Institute of Technology
Agnes Jocher is working on generating chemical kinetic mechanisms including PAH chemistry and testing their influence on soot production.
She received her Diploma in Engineering Sciences from the Technische Universität München and her doctoral degree in Mechanical Engineering from the RWTH Aachen University and the Université Paris VI in 2017. Within the jointly supervised Ph.D. program, the numerical part of the work was carried out at the Institute for Combustion Technology, RWTH Aachen University and the experiments at the Institut Jean le Rond d'Alembert, Université Pierre et Marie Curie Paris VI, Sorbonne Universités.
In her thesis, Agnes studied soot formation processes and combustion instabilities in laminar coflow flames modified by magnetic field gradients and acoustic pulsing. Flame characteristics and soot volume fraction fields were predicted using detailed chemistry and the Hybrid Method of Moments. Measurement techniques applied in the course of the thesis were high-speed luminosity measurements, Background Oriented Schlieren and one- and two-color Modulated Absorption/Emission techniques. A magnetic scaling of soot production similar to the scaling with oxygen was documented for non-premixed flames. For certain conditions, a trend reversal could be observed in partially premixed flames. Furthermore, it was shown experimentally and reproduced computationally that a magnetic field gradient can stabilize a spontaneousely oscillating non-premixed flame. A local inviscid stability analysis based on the results of the direct numerical simulation showed that the magnetic field reduces the perturbations’ growth rate. The study was completed by identifying a domain for that naturally oscillating flames can be stabilized and controlled by magnetic field gradients.