Lift enhancement by means of small-amplitude airfoil oscillations at low Reynolds numbers
Lift enhancement by means of small-amplitude airfoil oscillations at low Reynolds numbers
复制标题
通过低雷诺数下的小幅度翼型振荡来增强升力
DOI：
10.2514/1.j051014
复制
发表时间：
2011
期刊：
影响因子：
2.5
通讯作者：
M. Visbal
中科院分区：
文献类型：
--
作者：
D. Cleaver;Zhijin Wang;I. Gursul;M. Visbal
在NACA 0012翼型上进行了力和粒子图像测速测量，该翼型在过失速迎角和雷诺数为10，000时经历小振幅正弦插摆振荡。随着振荡频率的增加，由于前缘涡脱落并在翼型吸力面上对流，升力增加，阻力减小。在此范围内，升力系数随标准化的倾入速度近似线性地增加。由于与最不稳定的尾流频率、其次谐波和第一谐波的共振，升力系数出现局部最大值，从而产生最有效的增升条件。在更高的频率下，出现流场的第二模式。前缘涡流保持在更靠近翼型前缘的位置，并通过与向上运动的翼型碰撞而失去其相干性。为了捕捉这一冲击过程，进行了高保真度的计算模拟，显示了高度过渡性的流动和上下表面涡流之间的强烈相互作用。在该模式中，对于较大振幅，在高频下也可能发生升力突然损失。
Force and particle image velocimetry measurements were conducted on a NACA 0012 airfoil undergoing small-amplitude sinusoidal plunge oscillations at a poststall angle of attack and Reynolds number of 10,000. With increasing frequency of oscillation, lift increases and drag decreases due to the leading-edge vortices shed and convected over the suction surface of the airfoil. Within this regime, the lift coefficient increases approximately linearly with the normalized plunge velocity. Local maxima occur in the lift coefficient due to the resonance with the most unstable wake frequency, its subharmonic and first harmonic, producing the most efficient conditions for high-lift generation. At higher frequencies, a second mode of flowfield occurs. The leading-edge vortex remains nearer the leading edge of the airfoil and loses its coherency through impingement with the upward-moving airfoil. To capture this impingement process, high-fidelity computational simulations were performed that showed the highly transitional nature of the flow and a strong interaction between the upper and lower-surface vortices. A sudden loss of lift may also occur at high frequencies for larger amplitudes in this mode.
振荡低展弦比机翼的流动重新附着和涡流重组
影响因子：
2.5
作者：
Vardaki E
通讯作者：
Vardaki E