Dynamic Stall Experiments on a Rotor with High Cyclic Setting in Axial Inflow
Dynamic Stall Experiments on a Rotor with High Cyclic Setting in Axial Inflow
复制标题
轴向流入高循环设置转子的动态失速实验
DOI：
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发表时间：
2017
期刊：
影响因子：
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通讯作者：
M. Raffel
中科院分区：
文献类型：
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作者：
Till Schwermer;A. Gardner;M. Raffel
动态失速是现代直升机旋翼在快进和机动飞行条件下发生的限制性空气动力现象之一。在动态失速期间，旋翼后退侧的有效迎角超过静态失速角，并且观察到升力峰值以及俯仰力矩的负峰值。这些载荷对于叶片和俯仰连杆的结构完整性至关重要，因此限制了现代直升机的飞行包线。
分离的流动，特别是在旋转框架中，具有很强的三维性，在检查二维俯仰翼型时可以忽略这一点，其中假设模型中段的流动是二维的。因此，实验是在模型转子上进行的，例如在悬停室中。大多数（小型）悬停室存在两个主要缺点：通常转子在地面效应下运行，并且由于转子尾流的再循环，转子流入受到干扰。最接近全尺寸直升机周围流动的模型是在风洞中进行的实验中实现的，在风洞中可以实现快速向前飞行条件。然而，这些通常非常复杂且昂贵。
在哥廷根 DLR 转子测试设施 (RTG) 的设计阶段，考虑了三个主要方面：避免地面效应操作、提供规定的转子流入量并防止转子尾流再循环以及建造易于使用的设施，并具有良好的光学通道到达转子。这些方面导致了设计……
Dynamic stall is one of the limiting aerodynamic phenomena that occur on modern helicopter rotors during fast forward and maneuvering flight conditions. During dynamic stall the effective angle of attack on the retreating side of the rotor exceeds the static stall angle and a lift peak as well as a negative peak in the pitching moment are observed. These loads can be crucial regarding the blades and the pitch links structural integrity and therefore limit the flight envelope of modern helicopters.
Separated flows, especially in a rotating frame, are strongly three-dimensional, which is neglected when examining two-dimensional pitching airfoils where the flow is assumed to be two-dimensional in the mid-section of the model. Therefore experiments are conducted on model rotors, e.g. in hover chambers. Two major disadvantages apply to most (small) hover chambers: usually the rotor is operated in ground effect and the rotor inflow is disturbed due to recirculation of the rotor wake. The closest representation of the flow around a full-scale helicopter is achieved in experiments conducted in wind tunnels where it is possible to achieve fast forward flight conditions. However these are often very complex and expensive.
During the design phase of the rotor test facility (RTG) at the DLR in Gottingen, three major aspects were considered: avoidance of an operation in ground effect, supply of a defined rotor inflow with prevention of a rotor wake recirculation and construction of an easy to use facility with good optical access to the rotor. These aspects resulted in the design…