2017/11/14 by Gabriel B. Goodwin, Goodwin, Gabriel B., Elaine S. Oran +1
Engineering · Mathematics · #Combustion and Detonation Processes #Computational Fluid Dynamics and Aerodynamics #Gas Dynamics and Kinetic Theory
paper · pdf · doi:10.48550/arxiv.1711.05160
Multidimensional numerical simulations of a homogeneous, chemically reactive\ngas were used to study ignition, flame stability, and\ndeflagration-to-detonation transition (DDT) in a supersonic combustor. The\nconfiguration studied was a rectangular channel with a supersonic inflow of\nstoichiometric ethylene-oxygen and a transimissive outflow boundary. The\ncalculation is initialized with a velocity in the computational domain equal to\nthat of the inflow, which is held constant for the duration of the calculation.\nThe compressible reactive Navier-Stokes equations were solved by a high-order\nnumerical algorithm on an adapting mesh. This paper describes two calculations,\none with a Mach 3 inflow and one with Mach 5.25. In the Mach 3 case, the\nfuel-oxidizer mixture does not ignite and the flow reaches a steady-state\noblique shock train structure. In the Mach 5.25 case, ignition occurs in the\nboundary layers and the flame front becomes unstable due to a Rayleigh-Taylor\ninstability at the interface between the burned and unburned gas. Growth of the\nreaction front and expansion of the burned gas compress and preheat the\nunburned gas. DDT occurs in several locations, initiating both at the flame\nfront and in the unburned gas, due to an energy-focusing mechanism. The growth\nof the flame instability that leads to DDT is analyzed using the Atwood number\nparameter.\n