Japan Aerospace Exploration Agency Institute of Space Technology and Aeronautics
Japan Aerospace Exploration Agency Institute of Space Technology and Aeronautics
Japan Aerospace Exploration Agency Program Management and Integration Dept., Inst. of Space Tech. and Aeronautics
Japan Aerospace Exploration Agency Institute of Space Technology and Aeronautics
Japan Aerospace Exploration Agency Institute of Space Technology and Aeronautics
A water-cooled scramjet combustor was tested to study the effects of pressure, combustor length, fuel-injection style, and wall temperature on autoignited combustion performance. The tests were conducted with an inflow Mach number of 2.5; total pressure of air of 1, 1.5, and 2 MPa; and total temperature of air from 1,200 to 2,600 K. High-enthalpy air was produced using a vitiation heater. The combustion condition was detected by a temperature increase in the combustor, which was related to a local combustion condition. When hydrogen fuel was supplied transversely to the combustor wall downstream of the backward-facing step, the autoignited combustion performance degraded with increasing airflow pressure at a low total temperature of the vitiated air. The ignition region was around the second explosion limit. The presence of H2O in the air further retarded ignition under the high-pressure condition. In high-temperature conditions, the combustion performance improved with increasing pressure. With a long combustor with a downstream extension, the autoignited combustion limit of the air temperature became lower. A long separation region was presumed to exist downstream of the transverse fuel jet. Under such conditions, the potential for autoignited combustion could be improved. This effect of the extension of the combustor length decreased with increasing pressure. Parallel fuel injection from the step base showed a low autoignition tendency. In the parallel injection, autoignition would initiate at the base of the step, where the pressure was low and the size of the base was small. In the water-cooled combustor, the autoignited combustion limit of air temperature was higher than that in the uncooled combustor. This fact suggested that an ignition source existed near the wall, for example, in the separation region.
水冷スクラムジェット燃焼器の自発着火燃焼試験
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