Vortex-induced vibration (VIV) is the result of the interaction between the airfoil vibration and vortex shedding, and it frequently achieves the peak vibration amplitude in the lock-in region. Therefore, distinguishing the effect of the two disturbances in the lock-in region is important for understanding VIV. In this study, the NACA 0012 airfoil was investigated at high angles of attack; thus, the vortex could form and shed regularly downstream. The VIV was analyzed numerically and verified using the test data in references. The process of the vortex shedding was observed to be similar under different incoming flows, vibration amplitudes, and frequency ratios. In the V-shape lock-in region, the phase between the airfoil vibration and vortex shedding changes with the frequency ratio. When the frequency ratio is 1, the phase and strength of the vortex shedding remain almost constant with the vibration amplitude. Based on the features of the vortex shedding, a method of separating the disturbances caused by the airfoil vibration and the vortex shedding is proposed to investigate the mechanism of VIV from the perspective of energy balance. As the phase between the airfoil vibration and vortex shedding changes in the lock-in region, the vortex shedding provides negative aerodynamic damping (AD) in some phases and positive AD in other phases. The stability of the airfoil depends on the two disturbances mentioned above. VIV occurs only when the disturbance of the vortex shedding performs positive work (negative AD) and the disturbance of the airfoil vibration performs negative work (positive AD). When the vibration amplitude is small, VIV is dominated by the disturbance of the vortex shedding. When the vibration amplitude is high, the VIV is dominated by the disturbance of the airfoil vibration. As the vibration amplitude increases, the two form a balance, and the airfoil exhibits limit cycle oscillations. Based on the assumption of linear superposition, the theoretical limit vibration amplitudes of the airfoil under the two conditions in this study were 3° and 13.4°, respectively.

涡旋振动（VIV）是机翼振动与涡旋脱落之间相互作用的结果，它经常在锁定区域内达到峰值振动幅度。因此，在锁定区域区分两种干扰的影响对于理解VIV很重要。在这项研究中，NACA 0012机翼在高攻角下进行了研究。因此，涡流可能在下游定期形成并脱落。对VIV进行了数值分析，并使用了参考文献中的测试数据进行了验证。在不同的流入流量，振动幅度和频率比下，涡旋脱落的过程是相似的。在V形锁定区域中，翼型振动和涡旋脱落之间的相位随频率比而变化。频率比为1时 涡旋脱落的相位和强度随振动幅度几乎保持恒定。根据涡旋脱落的特点，提出了一种分离翼型振动和涡旋脱落引起的扰动的方法，从能量平衡的角度研究了VIV的机理。当翼型振动和涡流脱落之间的相位在锁定区域中发生变化时，涡流脱落在某些阶段提供负空气动力学阻尼（AD），在其他阶段提供正AD。机翼的稳定性取决于上述两个干扰。仅当涡旋脱落的扰动执行正功（负AD）并且机翼振动的扰动执行负功（AD正）时，才会发生VIV。振动幅度小的时候 VIV受到涡流脱落的干扰。当振动幅度高时，VIV受机翼振动的干扰所支配。随着振动幅度的增加，两者形成平衡，并且机翼表现出极限循环振荡。基于线性叠加的假设，本研究中两个条件下机翼的理论极限振动幅度分别为3°和13.4°。