Increasing the Passive Scalar Mixing Quality of Jets in Crossflow With Fluidics Actuators
Increasing the Passive Scalar Mixing Quality of Jets in Crossflow With Fluidics Actuators
复制标题
使用射流致动器提高横流中射流的被动标量混合质量
DOI：
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发表时间：
2012
期刊：
影响因子：
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通讯作者：
C. Paschereit
中科院分区：
文献类型：
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作者：
Arnaud Lacarelle;C. Paschereit
横流射流在工业中广泛用于均质或冷却任务。最近，脉动射流被研究作为一种手段，以提高这些结构的标量混合效率，无论是单个射流还是射流阵列。为了避免机械驱动流动的缺点（成本、维护），设计了一种基于流体振荡器的新型喷油器。在横流型通用射流中安装了4个喷嘴，并与配置标准非振荡射流的相同装置的混合效率进行了比较。在高速浓度测量技术的帮助下，在注射平面下游的三个位置测量了两种装置的标量混合质量。在所有测试的情况下，流体喷射器表现出比标准喷射器更好的时间均匀性，具有Danckwerts不混合准则的特征。对于定义的混合质量，使用流体喷射器可以将混合长度减少约50%。此外，新型喷油器的混合质量对射流对横流动量的变化不太敏感。射流喷射器的扑动运动导致射流在喷射位置的下游产生更宽的方位扩散。这增加了宏观和微观混合现象，从而导致混合质量的高增益。因此，流体振荡器在改善横流构型中射流的被动标量均匀化方面具有很强的潜力。ASME版权所有©2011
Jets in crossflow are widely used in the industry for homogenization or cooling tasks. Recently, pulsating jets have been investigated as a mean to increase the scalar mixing efficiency of such configurations, whether for a single jet or for an array of jets. To avoid the disadvantages of mechanically actuated flows (costs, maintenance), a new injector based on a fluidics oscillator has been designed. Four injectors have been implemented in a generical jet in crossflow configuration and the mixing efficiency of the setup was compared with the one of the same setup equiped with standard non oscillating jets. With help of high-speed concentration measurement technique, the scalar mixing quality of both setups was measured at three positions downstream of the injection plane. In all the cases tested, the fluidics injectors present a better temporal homogenization, characterized with the Danckwerts unmixedness criterion, than the standard jets. For a defined mixing quality, a decrease of the mixing length by approximately 50% can be achieved with the fluidics injectors. Furthermore, the new injectors exhibit a mixing quality which is less sensitive to variations of the jet to crossflow momentum. The flapping motion of the fluidics injectors induces a wider azimuthal spreading of the fluidics jets immediately downstream of the injection location. This increases the macro- and micromixing phenomea which lead then to the high gains in mixing quality. It is thus demonstrated that fluidics oscillators present a strong potential to improve the passive scalar homogenization of jet in crossflow configurations.Copyright © 2011 by ASME