The vortex wake and its induced velocity of a helicopter rotor operating near the ground at low forward speeds have been studied using a simplified free wake-ground vortex model.

本文用一简化自由涡模型模拟旋翼尾涡系，用一简单涡模拟地面涡，对近地低速飞行时旋翼尾涡系的畸变及其引起的诱导速度变化作了研究。

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Image method ideal vortex model is used for the analysis of how ground effect impacts wingtip vortex and airflow downwash angle.

采用镜像法理想涡模型分析了地面效应对翼尖涡位置和气流下洗角的影响；

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The large eddy simulation methods can be used to analysis and calculate the decay and transport rules of wake vortex in near ground phases, but it′s too complex and difficult to use.

采用大涡模拟方法可以分析和计算近地阶段尾涡消散和运动规律，但模型繁琐、计算复杂。

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Once established, the heat content of the air at ground level is enough to keep the vortex going.

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And I wish that we could just have a time machine and sort of vortex ourselves from place to place, but we are definitely going to cover the ground and get to Texas.

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