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Acoustic and shock waves in chemically reacting media

Leonie Boshoff-Mostert, University of Nebraska - Lincoln

Abstract

This study focuses on the interaction between mechanical processes and chemically reacting systems. The first analysis investigates combustion-driven acoustic oscillations by performing a linear stability analysis of a burner stabilized pre-mixed flame. Two models are considered: the thermodiffusive model (uncoupled model) and the fully coupled thermodiffusive-hydrodynamic model. The coupled model predicts that the system can become unstable at lower Lewis numbers than predicted by the uncoupled model. In the second analysis the stability of a steady propagating solid combustion front is investigated. Depending on the mode of ignition of the reaction in the solid, the combustion front can propagate via a deflagration or a detonation. The effect of thermal stress in the solid is incorporated in the lowering of activation energy by the amount of elastic potential energy due to compression. The coupling of the reaction with mechanical stress leads to an additional mechanism for the destabilization of a steady detonation. The third part of this work involves the construction of analytical Hugoniot curves for porous materials: the Hugoniot curve of a material typically relates the pressure (P) with the specific volume (v) for materials subjected to shock compression. The P-v Hugoniot is the locus of all the possible end states that can be achieved by a single shock wave passing through a material. The shock compression of porous materials can lead to so-called anomalous behavior where the final density of the material is less than the solid density. In the anomalous case the existing methods that are used to construct analytical Hugoniots generally fail to represent the behavior accurately. A new method is presented to construct Hugoniot curves for porous materials that requires only two parameters. The new method is then used to predict Hugoniot curves for inert mixtures. The Hugoniot curves for mixtures are determined for conditions of thermal equilibrium between the constituents of the mixture, and also thermal non-equilibrium. ^

Subject Area

Mathematics|Engineering, Chemical

Recommended Citation

Boshoff-Mostert, Leonie, "Acoustic and shock waves in chemically reacting media" (1999). ETD collection for University of Nebraska - Lincoln. AAI9929185.
http://digitalcommons.unl.edu/dissertations/AAI9929185

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