Percolating Reaction–Diffusion Waves (PERWAVES)—Sounding rocket combustion experiments

• Published in: Acta astronautica Vol. 177; pp. 639 - 651
• Main Authors: Palečka, Jan, Goroshin, Samuel, Higgins, Andrew J., Shoshin, Yuriy, de Goey, Philip, Angilella, Jean-Régis, Oltmann, Hergen, Stein, Andreas, Schmitz, Burkhard, Verga, Antonio, Vincent-Bonnieu, Sébastien, Sillekens, Wim, Bergthorson, Jeffrey M.
• Format: Journal Article
• Language: English
• Published: Elmsford Elsevier Ltd 01.12.2020; Elsevier BV
• Subjects: Combustion; Diffusion; Diffusion waves; Discrete combustion; Experiments; Flame propagation; Flame structure; Free convection; Gas mixtures; Heat sources; Ignition temperature; Metal combustion; Metal fuels; Microgravity; Microgravity science; Morphology; Oxygen; Percolation; Propagation modes; Reaction kinetics; Reaction–diffusion waves; Rocket flight; Scientific research; Sedimentation; Silica glass; Sounding rocket; Sounding rockets; Tubes; Xenon; Reaction–diffusion waves; Microgravity science; Metal combustion; Percolation; Discrete combustion; Sounding rocket
• ISSN: 0094-5765; 1879-2030
• DOI: 10.1016/j.actaastro.2020.07.033

Percolating reaction–diffusion waves in disordered random media are encountered in many branches of modern science, ranging from physics and biology to material science and combustion. Most disordered reaction–diffusion systems, however, have complex morphologies and reaction kinetics that complicate the study of the dynamics. Flames in suspensions of heterogeneously reacting metal-fuel particles is a rare example of a reaction–diffusion wave with a simple structure formed by point-like heat sources having well-defined ignition temperature thresholds and combustion times. Particle sedimentation and natural convection can be suppressed in the free-fall conditions of sounding rocket experiments, enabling the properties of percolating flames in suspensions to be observed, studied, and compared with emerging theoretical models. The current paper describes the design of the European Space Agency PERWAVES microgravity combustion apparatus, built by the Airbus Defense and Space team from Bremen in collaboration with the scientific research teams from McGill University and the Technical University of Eindhoven, and discusses the results of two sounding-rocket flight experiments. The apparatus allows multiple flame experiments in quartz glass tubes filled with uniform suspensions of 25-micron iron particles in oxygen/xenon gas mixtures. The experiments performed during the MAXUS-9 (April 2017) and TEXUS-56 (November 2019) sounding rocket flights have confirmed flame propagation in the discrete mode, which is a pre-requisite for percolating-flame behavior, and have allowed observation of the flame structure in the vicinity of the propagation threshold. •Percolating reaction–diffusion waves in disordered heterogeneous media.•Flames in suspensions of iron particles aboard MAXUS-9 & TEXUS-56 sounding rockets.•Iron powder as carbon-free carrier of green energy.