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Experimental analysis of turbulent structures and the effects of non-equilibrium on an axial vortex.

机译：湍流结构的实验分析以及轴流中非平衡的影响。

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摘要

Examples of the axial vortex include, dust devils, trailing line aircraft wake vortices, and tornadoes. Some of these vortices can prove hazardous to individuals and property. This necessitates that studies be conducted to understand their structure and to attempt to develop mathematical models of the flow physics involved. A wide variety of experimental techniques have been used in the past to study the vortex, with flow visualization and hotwire anemometry being chosen for this experiment. There have been many inadequate mathematical models proposed in the past. The experimental results obtained were compared to the work of Ash, Zardadkhan and Zuckerwar (2011) taking into account the effects of non-equilibrium pressure forces on the flow. Their work used an eddy viscosity model to satisfy closure of the Navier-Stokes equation. The applicability of this model was further accessed in the experiment.;For the purpose of this experiment a bi-wing vortex generator was constructed. The vortex generator was designed without a central body in an attempt to minimize the velocity deficit created by its wake. This was instead replaced with a small cylinder containing a bevel gear system to link the movement of one wing to the other so prices adjustments could be made simultaneously. In the experiment Flow Visualization via smoke injection into the wind tunnel was used to observe the structure of the vortex. These observations were used to determine which vortex generator and wind tunnel setting yielded the largest most stable vortex. With the vortex generator set at an angle of attack of +/-12º hotwire surveys employing a TSI 300 anemometer paired with an X-wire hot-film probe were then conducted on vortices at tunnel settings of 30 m/s and 40 m/s.;Velocity profiles consistent with axial vortices were observed in the hotwire surveys. These profiles, when compared to the profiles generated taking into account non-equilibrium pressure effects, indicated that pressure relaxation and therefore non-equilibrium forces had a meaningful effect on the axial vortices. The Reynolds stress data obtained in the experiment also indicated that the Reynolds stress follow a trend consistent with the eddy viscosity model though it was impossible to obtain fully conclusive results due to the x-films inability to obtain the "axial-azimuthal" Reynolds stress correlation. Further study is required to give a more comprehensive view of the effects of non-equilibrium conditions on axial vortices.
机译：轴向涡旋的实例包括尘埃，尾随飞机尾流涡旋和龙卷风。其中一些涡流可能对个人和财产构成危险。这就需要进行研究以了解其结构并尝试开发所涉及的流动物理学的数学模型。过去，已使用多种实验技术来研究涡流，并为此实验选择了流量可视化和热线风速仪。过去提出了许多不足的数学模型。考虑到非平衡压力对流动的影响，将获得的实验结果与Ash，Zardadkhan和Zuckerwar（2011）的工作进行了比较。他们的工作使用了涡流粘度模型来满足Navier-Stokes方程的封闭性。在实验中进一步研究了该模型的适用性。；为该实验的目的，构造了双翼涡流发生器。涡流发生器的设计中没有中心体，试图将其尾流产生的速度不足降到最低。取而代之的是一个装有锥齿轮系统的小圆柱体，该圆柱体将一个机翼的运动与另一个机翼的运动联系起来，因此可以同时进行价格调整。在实验中，通过将烟气注入风洞的流动可视化来观察涡旋的结构。这些观察结果用于确定哪个旋涡发生器和风洞设置产生最大的最稳定旋涡。然后将涡流发生器设置在攻角为+/-12º的热丝上，然后在30 m / s和40 m / s的隧道设置下，使用TSI 300风速仪与X线热膜探头配对，进行涡流测量在热线调查中观察到与轴向涡旋一致的速度分布。与考虑到非平衡压力影响而生成的曲线相比，这些曲线表明压力松弛以及因此的非平衡力对轴向涡旋产生了有意义的影响。实验中获得的雷诺应力数据还表明，雷诺应力遵循与涡流粘度模型一致的趋势，尽管由于x膜无法获得“轴向方位角”雷诺应力相关性而无法获得完全结论性的结果。需要进行进一步的研究以更全面地了解非平衡条件对轴向涡旋的影响。

著录项

  • 作者

    Thompson, Michael P.;

  • 作者单位

    Old Dominion University.;

  • 授予单位 Old Dominion University.;
  • 学科 Aerospace engineering.;Plasma physics.
  • 学位 M.S.
  • 年度 2016
  • 页码 163 p.
  • 总页数 163
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类 古生物学;
  • 关键词

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