To investigate the potential performance benets of tailored fuel injection in a scramjet engine, ow through a rectangular-to-elliptical shape-transitioning scramjet was simulated with two dierent combustor injection geometries: one with uniformlyspaced boundary-layer fuel injection, and the other with oblique-angle porthole injectors targeting the ow structures observed in engine simulations. Both engines utilized inlet injection to promote rapid ignition and burning of the combustor-injected fuel.The simulations were compared with experimental data for validation purposes. The tailored-injection engine fueled to an equivalence ratio of 1.24 was found to have superior mixing and combustion eciencies, improving upon the 1.33 equivalence ratio symmetric engine by 7% and 2%, respectively. Tailored injection was shown to be a promising method for improving scramjet performance, potentially allowing higher fuel eciency and a shorter combustor section. Nomenclature A/A t = ratio of local cross-section area to throat cross-section area g = acceleration due to gravity, m/s 2 F thrust = thrust force, N H = stagnation (total) enthalpy, M J/kg I sp = specic impulse, ṡ m = mass ow rate, kg/s M = Mach number P ∞ = freestream static pressure, P a P/P 1 = ocal static pressure normalized to pressure behind forebody shock Q = Q-criterion, 1 2 ( Ω 2 − S 2 ) q = dynamic pressure, kP a Re unit = unit Reynolds number, m −1 S = strain tensor T = static temperature, K u = unit velocity vector U ∞ = freestream velocity, m/s x = streamwise distance from forebody leading edge, mm y + = dimensionless wall distance Y = local species mass fraction Y stoich = stoichiometric local species mass fraction η comb = Oxygen-based combustion eciency, % η mix = Oxygen-based mixing eciency, % ρ = density, kg/m 3 ∂ 1 ρ = ∇ρ ·û φ = fuel equivalence ratio Ω = vorticity tensor 2 Downloaded by UNIVERSITY OF ILLINOIS on October 1, 2015 | http://arc.aiaa.org |