Vortex-Induced Vibration and Frequency Lock-In of an Airfoil at High Angles of Attack
Vortex-Induced Vibration and Frequency Lock-In of an Airfoil at High Angles of Attack
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DOI：
10.1115/gt2014-25648
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发表时间：
2014-06
期刊：
影响因子：
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通讯作者：
Fanny M. Besem;Joshua D. Kamrass;Jeffrey P. Thomas;D. Tang;R. Kielb
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文献类型：
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作者：
Fanny M. Besem;Joshua D. Kamrass;Jeffrey P. Thomas;D. Tang;R. Kielb
涡激振动是一种流体不稳定性，存在于许多领域，包括海上平台，风力涡轮机和涡轮机。由于二次流产生的旋涡对弹性结构施加周期性的不稳定力，导致潜在的危险振动。在某些情况下，脱落频率会锁定在结构的固有频率内，导致结构发生极限环振荡。这些高振幅振动会导致材料疲劳，是结构失效的常见原因。本文使用频域、谐波平衡、计算流体动力学（CFD）代码来预测翼型在非常大的迎角下的锁定。使用增量相位迭代法确定自然脱落频率，并通过在不同的振荡幅度和频率下强制翼型运动来识别锁定区域。数值计算结果与NACA0012翼型在深失速条件下的风洞试验数据成功地进行了比较。Copyright © 2014 by ASME
Vortex-induced vibration is a fluid instability present in many areas, including offshore platforms, wind turbines, and turbomachinery. The vortices due to secondary flows exert an periodic unsteady force on the elastic structure, leading to potentially dangerous vibrations. Under certain circumstances, the shedding frequency can lock into the structure natural frequency and lead to limit cycle oscillations. These high amplitude vibrations can cause material fatigue, and are a common source of structural failure.This work uses a frequency domain, harmonic balance, CFD code to predict the lock-in of an airfoil at very high angles of attack. The natural shedding frequency is found using a delta phase per iteration method, and the lock-in region is identified by enforcing airfoil motion at different oscillation amplitudes and frequencies. The numerical results are successfully compared to experimental data from wind tunnel testing on a NACA0012 airfoil at deep stall conditions.Copyright © 2014 by ASME