High Fidelity Measurements and Modeling of Combustion Instabilities
Technical Report,01 Aug 2015,31 Jan 2019
UNIVERSITY OF CALIFORNIA LOS ANGELES LOS ANGELES United States
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Acoustically coupled combustion instabilities can result in large scale, potentially catastrophic pressure oscillations in a range of propulsion systems, including both liquid rocket engines LREs and gas turbine engines. Such combustion instabilities are characterized by self-sustaining, generally spontaneously excited, large amplitude oscillations associated with natural acoustic modes established within a combustion chamber. New methods of analysis, measurement, prediction and designdevelopment are required to make progress toward a detailed understanding of the interactions among hydrodynamics, acoustics, turbulent mixing, and chemical kinetics that control whether a combustor will be stable or unstable. Our team has undertaken a collaborative research project in which researchers at both Purdue and UCLA pursue the study of reactive flow fields that can shed light on greater understanding of these instabilities and the ability to control them in practical propulsion systems. Research at UCLA during the funding period has involved fundamental experimental studies on acoustically-coupled, condensed phase combustion processes, with a major focus on exploration of 1 newly-discovered periodic partial flame extinction as a coupling mode for acoustically-driven non-premixed combustion 2 the effects of nanoparticulate additives both energetic and inert on liquid fuel droplet combustion in quiescent surroundings, including model comparisons 3 the effects of nano-particulates on fuel droplet combustion in the presence of chamber-based acoustic perturbations 4 periodic partial extinction and full extinction strain rates for nano-fuels and 5 initiation of alternative combustion configurations for further studies, especially in the gas phase. The research at Purdue has encompassed concurrent high-fidelity simulations and experimental tests of a model combustor that exhibits self-excited instabilities that are dependent on flow and geometric parameters.
- Combustion and Ignition