Expansion and mixing processes of underexpanded supercritical fuel jets injected into superheated conditions
Expansion and mixing processes of underexpanded supercritical fuel jets injected into superheated conditions
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DOI：
10.2514/6.1997-2852
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发表时间：
1997-07
期刊：
影响因子：
2.9
通讯作者：
P. Wu;M. Shahnam;K. Kirkendall;C. Carter;A. Nejad
中科院分区：
文献类型：
--
作者：
P. Wu;M. Shahnam;K. Kirkendall;C. Carter;A. Nejad
对Theexpansionandmixingprocessesofunderexpandedsupercriticalfueljetsinjectedintosuperheatedconditions进行了实验研究。以乙烯为燃料，氮气为环境气体。用马赫盘的位置、大小和膨胀角表征了近场喷流羽流结构。超临界乙烯喷流的马赫盘位置与理想气体喷流的马赫盘位置相匹配。然而，马赫盘的尺寸和膨胀角随着喷射温度接近临界值而增大。通过自发拉曼散射测量燃料摩尔分数和温度分布来表征远场混合过程。燃料摩尔分数分布服从高斯函数，而由于燃料射流的膨胀和加速，喷流羽流内部的温度分布呈现明显的Dee cit。当喷射条件接近临界点时，观察到以下现象：1)乙烯中心线摩尔分数增加，2)化学计量水平的射流宽度增加，3)最大浓度一半处的射流宽度不变，4)温度变化不明显。这是由于喷油条件接近临界点时，喷油质量下降和燃油凝结较大所致。
Theexpansionandmixingprocessesofunderexpandedsupercriticalfueljetsinjectedintosuperheatedconditions were experimentally studied. Ethylene was used as the fuel, and nitrogen was the ambient gas. The near-e eld jet plume structure was characterized by the location and size of the Mach disk and the expansion angle. The Mach disk location of the supercritical ethylene jet matches that of an ideal-gas jet. The size of the Mach disk and the expansion angle, however, increase as the injection temperatureapproaches the critical value. Thefar-e eld mixing processes were characterized by measuring fuel mole fraction and temperature distributions using spontaneous Raman scattering. Fuel mole fraction distributions follow a Gaussian function, whereas temperature distributions exhibit a dee cit inside the jet plume because of the expansion and acceleration of the fuel jet. As the injection condition approached the critical point, the following observations were made: 1 ) the ethylene centerline mole fraction increased, 2 ) the jet width at the stoichiometric level increased, 3 ) the jet width at half the maximum concentration remained the same, and 4 ) the temperature dee cit became more signie cant. These results were attributed to the larger injected fuel mass e ow and fuel condensation when the jet injection conditions approach the critical point.