To predict helicopter vortex ring state boundary is necessary for flight safety.
直升机涡环状态边界的确定对直升机飞行安全具有重要意义。
A reasonable criterion of vortex ring state boundary for helicopter is acquired based on model rotor tests.
通过模型旋翼试验得到了合理的直升机涡环边界判据，并由此计算得到了直升机通用涡环状态边界。
The results show that the interaction between a viscous vortex ring and a free surface is different from the inviscid one.
结果表明：由于粘性的存在，使得涡环与自由表面的相互作用与无粘情形相比有许多不同。
Physically, at a special critical wave speed the flow may have a naturally periodical separated-reattached pattern, with each wave trough capturing a stable vortex ring.
物理上看，在一个特定的临界行波速下会形成自发的周期性分离再附流，每个波谷的分离区捕获一个稳定的涡环。
Theoritical analysis has shown that triangular singularity distribution has special advantages over the other ones(vortex ring or constant distribution) in the prediction of nonuniform flow field.
理论分析表明三角形奇点分布形态在非均匀流场计算中具有其独特的优越性。
To investigate helicopter vortex-ring state, the phenomenon and reason of helicopter vortex-ring state flight accident is analyzed from the view of helicopter aerodynamics.
针对直升机特有的涡环飞行状态，根据直升机空气动力学理论，分析了直升机涡环状态飞行事故的现象及成因。
In addition to balance vortex internal pressure of compressed gas beyond, still provides top and bottom sealing force between the slot, the sealing force to achieve by floating sealing ring.
除了平衡涡旋内部压缩气体压力以外，还提供了顶端和底槽间的密封力，该密封力靠浮动密封圈来实现。
The result shows that the model of neural network can predict the effect of blade negative-twist on helicopter vortex-ring state.
计算结果表明，神经网络模型能够准确预测桨叶负扭度对直升机涡环状态的影响。
Former deputy leaves on the cover can reduce the imports of the vortex impeller and particle loss of the wear and tear on the seal ring.
前盖板上的副叶片可以减少叶轮进口的旋涡损失和颗粒对密封环的磨损。
A new type of the double-vortex beam is generated by the coaxial superposition of vortex beams with two different topological charges, whose intensity distribution is double-ring.
利用带有不同拓扑荷数的两束涡旋光束进行共轴叠加，产生了一种新型光束双涡旋光束，其光强分布为双环结构。
A new type of the double-vortex beam is generated by the coaxial superposition of vortex beams with two different topological charges, whose intensity distribution is double-ring.
利用带有不同拓扑荷数的两束涡旋光束进行共轴叠加，产生了一种新型光束双涡旋光束，其光强分布为双环结构。
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