The current study analyzes the dynamic response of a NACA 0015 finite-span wing to a time-varying freestream in an unsteady wind tunnel at a mean Reynolds number of $1.0\times {10}^5$. The aerodynamic response of the wing can be categorized based on the angle of attack and the degree of flow separation on the suction side of the wing. When the suction side is dominated by separated flow, either at low angles of attack with long laminar separation bubbles or at high, poststall, angles of attack, the lift is enhanced by the favorable pressure gradient during freestream acceleration and decremented by the adverse pressure gradient during freestream deceleration. In these cases, the sectional lift coefficient is shown to oscillate by as much as $\pm 0.1$ due to the unsteady pressure gradient. Comparatively, regions of attached flow on the wing surface remain largely unaffected by the time-varying conditions, regardless of the reduced frequency. Discrepancies between the measured lift and the estimated response from Isaacs’s theory demonstrate that the coupling between the viscous flow separation and the unsteady conditions dominates the unsteady aerodynamic response.

当前的研究分析了 NACA 0015 有限翼展机翼对非定常风洞中时变自由流的动态响应，平均雷诺数为$1.0\times {10}^5$。机翼的空气动力学响应可以根据迎角和机翼吸力侧的气流分离程度进行分类。当吸力侧以分离流为主时，无论是在具有长层流分离气泡的低迎角下还是在高失速后迎角下，升力在自由流加速期间因有利压力梯度而增强，并因逆压力梯度而减小在自由流减速期间。在这些情况下，截面升力系数的振荡幅度为$\pm 0.1$由于压力梯度不稳定。相比之下，无论频率如何降低，机翼表面的附着流区域在很大程度上不受时变条件的影响。测量的升力和艾萨克斯理论估计的响应之间的差异表明，粘性流分离和非定常条件之间的耦合主导了非定常空气动力响应。