Effects of Time Scales on Lift of Airfoils in an Unsteady Stream
Effects of Time Scales on Lift of Airfoils in an Unsteady Stream
复制标题
时间尺度对不稳定流中机翼升力的影响
DOI：
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发表时间：
1994
期刊：
影响因子：
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通讯作者：
Chih
中科院分区：
文献类型：
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作者：
I. Gursul;Hank Lin;Chih
在非定常空气动力学中，由于折合频率与非定常性有关，一直被认为是主要的控制参数。在这项研究中，我们研究了几个不同展弦比的三角翼和二维机翼在非定常周期性自由振动中的响应。我们发现，在某些工作条件下，翼型的升力可能是也可能不是折合频率的函数，这取决于前缘分离涡是否能在机翼上保持静止。对于带有固定前缘涡的三角翼，升力不是折合频率的函数。然而，如果前缘涡脱落并向下游对流，则升力取决于折减频率。
In unsteady aerodynamics, the reduced frequency has always been considered as the predominant controlling parameter because it relates to the unsteadiness. In this study, we examined the responses of several delta wings of varying aspect ratio and a two-dimensional wing in an unsteady periodic freestream. We found that in certain operating conditions, the lift of the airfoils may or may not be a function of the reduced frequency, depending on whether the leading-edge separation vortex can remain stationary on the wing or not. For delta wings with attached, stationary leading-edge vortices, the lift forces are not a function of the reduced frequency. However, if the leading-edge vortices shed and convect downstream, then the lift force depends on the reduced frequency.