Influences of Domain Symmetry on Supersonic Combustion Modeling

High-fidelity Improved Delayed Detached Eddy Simulation modeling is applied to examine the influence of the symmetry plane on the supersonic flow and combustion characteristics in a round-to-elliptic-transition scramjet combustor. A quarterly split domain and the full domain are modeled by using up to 0.14 billion cells and a third-order scale-selective discretization scheme. The combustion chemistry is described by the finite-rate partially stirred reactor model based on multicomponent diffusion and a skeletal kerosene mechanism with 19 species/53 reactions. Time-averaged pressure, temperature, Mach number, and heat release rate are compared to examine the influence of the symmetry assumption on the mean flow fields. The exchanges of mass, momentum, and energy across the symmetry planes are analyzed. Considerable increases in the combustion efficiency and total pressure loss occur when applying the full domain, although with the similar mixing efficiency. Turbulence spectrum analysis confirms the -8/3 power-law for supersonic flows, and the inertial subrange is found to be shorter in the quarter-domain modeling. A comparison of the Borghi's diagrams shows that the data points shift from the flamelet mode to the thin reaction zone mode when using the full domain, and at least 1/3 of them cannot be described by fast-chemistry combustion models.