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GALCIT Colloquium

Friday, May 6, 2016
3:00pm to 4:00pm
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Guggenheim 133 (Lees-Kubota Lecture Hall)
Thesis Defense: Mixing, Chemical Reactions, and Combustion in Supersonic Flows
Niccolo Cymbalist, PhD Candidate , GALCIT, California Institute of Technology,
Recent proof-of-concept developments in ground and flight testing of air-breathing vehicles in the flight Mach 5-7 range have renewed interest in fundamental physical processes that contribute to mixing, chemical reactions, and combustion in supersonic flows. Supersonic combustion is characterized by intense turbulence, compressibility effects, short residence times available for fuel-air dispersion, mixing, and reaction, and, at low-supersonic flight Mach numbers, only moderate pre-ignition temperatures to promote autoignition. Improved understanding of relevant physical processes can help develop predictive models for the spatial and temporal distribution of heat-release in supersonic combustors. 
 
Experiments were conducted to investigate reacting transverse jets in supersonic crossflow at order-unity Damköhler numbers, using chemiluminescence and schlieren image-correlation velocimetry. In particular, we examine ignition-delay length and convective velocity dependencies on jet-fluid molar mass, jet diameter, and jet inclination. A combustion-modeling framework is proposed for large-eddy simulations (LES) of supersonic, compressible, turbulent combustion in a regime of autoignition-dominated distributed reaction zones (DRZ). The proposed evolution-variable manifold (EVM) framework incorporates an ignition-delay data-driven induction model with a post-ignition manifold that uses a Lagrangian convected 'balloon' reactor model for chemistry tabulation.
 
For more information, please contact Vidyasagar by phone at 626-395-5760 or by email at vvidyasa@caltech.edu.