Abstract Ground effects on the stability of separated flow around a NACA 4415 airfoil at low Reynolds numbers
  • 主题
高级搜索  >
历史搜索 清空历史
首页> 外文期刊>Aerospace science and technology >Ground effects on the stability of separated flow around a NACA 4415 airfoil at low Reynolds numbers
【24h】

Ground effects on the stability of separated flow around a NACA 4415 airfoil at low Reynolds numbers

机译：低雷诺数时地面对NACA 4415机翼周围分离流稳定性的影响

获取原文
获取原文并翻译 | 示例
           
页面导航
  • 摘要
  • 著录项
  • 相似文献
  • 相关主题

摘要

AbstractWe perform a linear BiGlobal modal stability analysis on the separated flow around a NACA 4415 airfoil at low Reynolds numbers (Re=300–1000) and a high angle of attack (α=20°), with a focus on the effect of the airfoil's proximity to two different types of ground: a stationary ground and a moving ground. The results show that the most dominant perturbation is a Kelvin–Helmholtz mode, which gives rise to a supercritical Hopf bifurcation to a global mode, leading to large-scale vortex shedding at a periodic limit cycle. As the airfoil approaches the ground, this mode can become more unstable or less unstable, depending on the specific type of ground: introducing a stationary ground to an otherwise groundless system is destabilizing but introducing a moving ground is stabilizing, although both effects weaken with increasingRe. By performing a Floquet analysis, we find that short-wavelength secondary instabilities are damped by a moving ground but are amplified by a stationary ground. By contrast, long-wavelength secondary instabilities are relatively insensitive to ground type. This numerical–theoretical study shows that the ground can have an elaborate influence on the primary and secondary instabilities of the separated flow around an airfoil at lowRe. These findings could be useful for the design of micro aerial vehicles and for improving our understanding of natural flyers such as insects and birds.
机译： 摘要 我们对低雷诺数的NACA 4415机翼周围的分离流进行线性BiGlobal模态稳定性分析（ R e = 300 –1000）和高攻角（ α < mml：mo> = 20 ° ），重点关注机翼靠近两种不同类型地面的影响：固定地面和移动地面。结果表明，最主要的扰动是开尔文-亥姆霍兹模式，这会导致超临界霍普夫分岔成整体模式，从而导致周期性周期性循环中的大规模涡旋脱落。当机翼接近地面时，此模式可能变得更不稳定或更少不稳定，具体取决于地面的具体类型：将静止地面引入到没有地面的系统中会变得不稳定，而引入移动地面会变得稳定，尽管两种作用都会随着增加而减弱 Re 。通过进行Floquet分析，我们发现短波次级不稳定性被运动的地面所阻尼，但被静止的地面所放大。相比之下，长波长次级不稳定性对地面类型相对不敏感。这项数值理论研究表明，地面对低 Re 翼型周围分离流的主要和次要不稳定性具有复杂的影响。这些发现对于设计微型飞行器和增进我们对诸如昆虫和鸟类等自然飞行物的理解很有用。

著录项

相似文献

  • 外文文献
  • 中文文献
  • 专利
获取原文

客服邮箱：kefu@zhangqiaokeyan.com

京公网安备：11010802029741号 ICP备案号：京ICP备15016152号-6 六维联合信息科技 (北京) 有限公司©版权所有

  • 客服微信

  • 服务号