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Simulating Unstart in an Axisymmetric, Supersonic Cavity Flameholder
[Technical Report, Memorandum Report]
NAVAL RESEARCH LAB WASHINGTON DC
Pagination or Media Count:
Axisymmetric cavity combustors are not subjected to the corner boundary-layer effects present in planar combustors, making them an attractive configuration for robust flam holding. Experiments at the University of Illinois have investigated ethylene combustion in an axisymmetric combustor using a cavity flameholder with inlet flow at Mach 4.5. Cavity flameholding was achieved for a range of fuel equivalence ratios. In the current study, the Naval Research Laboratorys discontinuous Galerkin finite element method code, the JENRE Multiphysics Framework, was used to simulate combustion in the University of Illinois ACT-II cavity combustor facility. Fuel equivalence ratio was increased from 1.0 until unstart occurred due to thermal choking. The simulations were three-dimensional and an eighth-symmetry domain was used with rotationally periodic boundary conditions in order to reduce computational expense. Simulations were performed both with artificial viscosity and with physical diffusion and the results are compared. The unstart process was initiated at highly fuel-rich conditions due to thermal choking.
[A, Approved For Public Release]