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Solar-Thermal Engine Testing


A solar-thermal engine serves as a high-temperature solar-radiation absorber, heat exchanger, and rocket nozzle, collecting concentrated solar radiation into an absorber cavity and transferring this energy to a propellant as heat. Propellant gas can be heated to temperatures approaching 4,500 ℉ and expanded in a rocket nozzle, creating low thrust with a high specific impulse (I_(sp)). The Shooting Star Experiment (SSE) solar-thermal engine is made of 100 percent chemically vapor deposited (CVD) rhenium. The engine 'module' consists of an engine assembly, propellant feedline, engine support structure, thermal insulation, and instrumentation. Engine thermal performance tests consist of a series of high-temperature thermal cycles intended to characterize the propulsive performance of the engines and the thermal effectiveness of the engine support structure and insulation system. A silicone-carbide electrical resistance heater, placed inside the inner shell, substitutes for solar radiation and heats the engine. Although the preferred propellant is hydrogen, the propellant used in these tests is gaseous nitrogen. Because rhenium oxidizes at elevated temperatures, the tests are performed in a vacuum chamber. Test data will include transient and steady state temperatures on selected engine surfaces, propellant pressures and flow rates, and engine thrust levels. The engine propellant-feed system is designed to supply GN_2 to the engine at a constant inlet pressure of 60 psia, producing a near-constant thrust of 1.0 1b. Gaseous hydrogen will be used in subsequent tests. The propellant flow rate decreases with increasing propellant temperature, while maintaining constant thrust, increasing engine I_(sp). In conjunction with analytical models of the heat exchanger, the temperature data will provide insight into the effectiveness of the insulation system, the structural support system, and the overall engine performance. These tests also provide experience on operational aspects of the engine and associated subsystems, and will include independent variation of both steady state heat-exchanger temperature prior to thrust operation and nitrogen inlet pressure (flow rate) during thrust operation. Although the Shooting Star engines were designed as thermal-storage engines to accommodate mission parameters, they are fully capable of operating as scalable, direct-gain engines. Tests are conducted in both operational modes. Engine thrust and propellant flow rate will be measured and thereby I_(sp). The objective of these tests is to investigate the effectiveness of the solar engine as a heat exchanger and a rocket. Of particular interest is the effectiveness of the support structure as a thermal insulator, the integrity of both the insulation system and the insulation containment system, the overall temperature distribution throughout the engine module, and the thermal power required to sustain steady state fluid temperatures at various flow rates.......

【作者名称】: Stephen Tucker, Pat Salvail
【作者单位】: NASA Marshall Space Flight Center, Marshall Space Flight Center, AL 35812
【关 键 词】: Solar-Thermal Engine Testing
【会议名称】: Space Technology and Applications International Forum (STAIF 2002), Feb 3-6, 2002, Albuquerque, New Mexico
【期刊论文数据库】: [DBS_Articles_01]
【期刊论文编号】: 101,026,048
【摘要长度】: 2,983
【会议地点】: Albuquerque, NM(IS);Albuquerque, NM(IS);Albuquerque, NM(IS);Albuquerque, NM(IS);Albuquerque, NM(IS);Albuquerque, NM(IS)
【会议组织】: NASA Marshall Space Flight Center, Marshall Space Flight Center, AL 35812
【会议时间】: 2002
【上篇论文】: 外文会议 - Eclipse 500 Very Light Jet Aircraft Computer System(ACS) Grey - box Simulation
【下篇论文】: 外文会议 - HIGH ACCURACY ABSOLUTE LONG DISTANCE METROLOGY USING FEMTOSECOND LASERS: OPTICAL HETERODYNING, ELECTRICAL HETERODYNING AND APPLYING FSL-SYSTEMS

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