ME 250 Seminar Series: Dr. Joseph Kalman

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Leveraging Crystalline Oxidizer Microstructure to Advance Multiphase Combustion Systems

Abstract:

Next generation propulsion systems are needed to improve the range, speed, and safety of rocket motors whereas chemical looping combustion is required to modernize power production and resource utilization. Advancements in both applications relies on resolving how the microstructure of crystalline oxidizers influences system reactivity. Ammonium perchlorate (AP) and copper (II) oxide are widely used oxidizers for solid rocket motors and chemical looping combustion, respectively. However, the oxidizers’ microstructural evolution during reaction has not yet been used to control combustion processes. This talk presents recent and ongoing work trying to leverage the intimate connection between crystalline microstructure and reactivity. For propulsion applications, shear rate-controlled recrystallization of AP is shown to directly influence the heat release amount and dynamics based upon the crystal orientation. Preliminary results indicate that crystals exhibiting the lowest exothermicity in low heating rate conditions burn the fastest. For power production, the physics of a new flame-based approach to chemical looping combustion are studied using inverse hybrid CuO(s) dust flames. Experimental measurements indicate that with greater CuO(s) particle loading, flame propagation begins to transition from H2-O2 dominated system to H2-CuO controlled reaction. This result will facilitate improved control of particle microstructure to reduce particle attrition in chemical looping applications. These finding demonstrate a path forward to improving combustion applications through material science.