The effects of injection behind a pylon upstream of a supersonic combustion chamber were evaluated for liquid JP-10 and gaseous ethylene. A generic, rearward-facing, rectangular step was used as the primary ameholding mechanism. A pilot-hydrogen ame injected from the base of the step provided ignition. The fuel was injected from a 1.5-mm-diam wall ori ce behind a thin triangular cross section pylon placed in the isolator at 10 step heights upstream of the step. The role of the pylon is to facilitate the penetration and the spreading of the liquid jet. Tests were performed under connected-pipe conditions in a Mach 1.6 air ow channel and air stagnation temperatures to 900 K, corresponding to the beginning of the hypersonic ight regime. The hydrogen, ethylene, and JP-10 ow rates were modulated during the tests and wall pressures and temperatures were measured along the duct and in the recirculation region. Shadowgraph imaging indicated the effect of injection on the isolator shock train and the combustion chamber mixing. Combustion without upstream ashback has been observed with isolator JP-10 equivalence ratios to 0.5.
Nomenclature
D= diameter, cm H = height of rearward-facing step, 12 mm h = jet penetration height, cm P = pressure, KPa, MPa q = dynamic pressure ratio T = temperature, K X = axial location, cm Y = transverse location parallel to contoured sides of nozzle, cm Z = transverse location perpendicular to contoured sides of nozzle, cm g = ef ciency U = equivalence ratio Subscripts air = air property C2H4 = ethylene property fuel = fuel property H2 = hydrogen property inj = injector property JP-10 = JP-10 property jet/air = ratio of jet/air property mix = mixing 0 = stagnation property 32 = sauter mean diameter = freestream property
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