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>Thermal Characteristics and Structure of Fully-Modulated, Turbulent Diffusion Flames in Microgravity
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Thermal Characteristics and Structure of Fully-Modulated, Turbulent Diffusion Flames in Microgravity
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机译:微重力下全调制湍流扩散火焰的热特性和结构
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摘要
Turbulent jet diffusion flames are studied in microgravity and normal gravity under fully-modulated conditions for a range of injection times and a 50% duty cycle. Diluted ethylene was injected through a 2-mm nozzle at a Reynolds number of 5,000 into an open duct, with a slow oxidizer co-flow. Microgravity tests are conducted in NASA's 2.2 Second Drop Tower. Flames with short injection times and high duty cycle exhibit a marked increase in the ensemble-averaged flame length due to the removal of buoyancy. The cycle-averaged centerline temperature profile reveals higher temperatures in the microgravity flames, especially at the flame tip where the difference is about 200 K. In addition, the cycle-averaged measurements of flame radiation were about 30% to 60% greater in microgravity than in normal gravity.
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机译:在全调制条件下,在一定的喷射时间和50%的占空比条件下,在微重力和法向重力下研究了湍流射流扩散火焰。将稀释的乙烯通过2毫米喷嘴以雷诺数5,000注入到敞开的管道中,并缓慢加入氧化剂。微重力测试是在NASA的2.2 Second Drop Tower中进行的。短喷射时间和高占空比的火焰由于消除了浮力而使整体平均火焰长度显着增加。周期平均的中心线温度曲线显示了微重力火焰的温度更高,尤其是在火焰尖端处的温度差大约为200K。此外,火焰重力的周期平均测量值比微重力大约高30%至60%在正常重力下。
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