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In-flight simulation of wake encounters using deformed vortices

机译：飞行中使用变形涡流模拟尾流相遇

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During the decay process the shape of wake vortices changes significantly which has an influence on the encounter characteristics, hence on the encounter hazard. In order to evaluate the influence of vortex deformation on the wake encounter hazard, in-flight simulations with the DLR research aircraft ATTAS were carried out. For a realistic analysis of wake encounters flow fields of matured vortices were generated with large eddy simulations. These flow fields were used for the determination of histories of induced forces and moments acting on the wake encountering aircraft. The force and moment histories were then fed into the equations of motions of the non-linear six degree-of-freedom in-flight simulation of the DLR research aircraft ATTAS. In order to compare different stages of vortex deformation, encounters were simulated in flight with wavy vortices and vortex rings. The most important benefit of the in-flight-simulation is the realistic environment, which enables a realistic assessment of pilots' encounter acceptance. The analysed scenario was of a wake encounter during final approach. The encounter conditions correspond to separation distances of about 4nm and 5nm behind an aircraft of the 'heavy' category. During the encounters the ATTAS was flown under manual control. Altogether 31 encounters were simulated in flight, 9 with wavy vortices and 22 with vortex rings. The analysis of the results shows that with increasing vortex deformation the encounter impact acts increasingly in all degrees of freedom. Apparently, pilots assess roll-dominated encounters as more dangerous, which is why the unacceptability threshold is higher for encounters with vortex rings than for those with wavy vortices. Besides this unacceptability boundary, a harmlessness boundary can be determined, which seems to be independent from the degree of vortex deformation. This is a most important outcome of the flight test described in this paper. Although, due to the very limited number of flight tests performed, no clear correlation between the pilot ratings and objective measures could be assessed, an acceptance boundary for the roll control ratio could be determined below which the effects of vortex deformation seem to be negligible.
机译：在衰减过程中，尾流涡流的形状发生显着变化，这会影响相遇特性，从而影响相遇危险。为了评估涡流变形对尾流遭遇危险的影响，使用DLR研究飞机ATTAS进行了飞行模拟。为了进行现实的尾流接触分析，通过大型涡流模拟生成了成熟涡旋的流场。这些流场用于确定感应力和作用在遇到尾流的飞机上的力矩的历史。然后，将力和力矩的历史记录输入到DLR研究型飞机ATTAS的非线性六自由度飞行模拟的运动方程中。为了比较涡旋变形的不同阶段，在飞行中模拟了波浪涡旋和涡旋环的相遇。飞行中模拟的最重要好处是真实的环境，可以对飞行员的遭遇接受度进行真实的评估。分析的场景是在最终进近过程中遇到的尾声。遭遇条件对应于“重型”类别飞机后约4nm和5nm的分离距离。遇到期间，ATTAS是在手动控制下飞行的。在飞行中总共模拟了31次相遇，其中有9次有波浪涡旋，有22次有涡旋环。结果分析表明，随着涡旋变形的增加，相遇冲击在所有自由度上的作用越来越大。显然，飞行员将侧倾主导的相遇评估为更加危险，这就是为什么与涡流环相遇的可接受性阈值高于波浪环的相较而言更高的原因。除了此不可接受的边界外，还可以确定无害边界，该边界似乎与涡旋变形的程度无关。这是本文描述的飞行测试的最重要结果。尽管由于进行的飞行测试数量非常有限，无法评估飞行员额定值与客观测量之间的明确关联，但是可以确定侧倾控制比的接受边界，在该边界以下，涡流变形的影响似乎可以忽略不计。

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    《The Aeronautical Journal》 |2013年第1196期|997-1018|共22页
  • 作者

    D. Vechtel;

  • 作者单位

    DLR German Aerospace Center, Institute of Flight Systems Department of Flight Dynamics and Simulation Braunschweig Germany;

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