Energy Harvesting Performance of Thick Oscillating Airfoils Using a Discrete Vortex Model
Energy Harvesting Performance of Thick Oscillating Airfoils Using a Discrete Vortex Model
复制标题
使用离散涡模型的厚振荡翼型的能量收集性能
DOI：
10.1115/1.4056339
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发表时间：
2022
期刊：
影响因子：
--
通讯作者：
Liburdy, Jim A.
中科院分区：
文献类型：
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作者：
Kamrani Fard, Kiana;Ngo, Vickie;Pence, Deborah;Liburdy, Jim A.
采用无粘离散涡模型（DVM）预测了厚翼型振荡的能量收集性能。本文模拟了具有不同前缘几何形状的美国国家航空咨询委员会（NACA）翼型在约化频率范围内的正弦升沉和俯仰运动，其中f为翼型的升沉频率，f为弦长，f为自由速度。翼型在中弦附近俯仰，升沉和俯仰幅度分别为和，已知在峰值能量收集效率范围内。基于计算流体动力学（CFD）模拟确定的瞬态局部壁应力分布，提出了一种涡脱落起始准则，并结合了前缘分离的时间和位置。缩放脱落时间被证明是预测的范围内减少频率使用的时间尺度的基础上的前缘剪切速度和曲率半径。脱落涡流的对流速度也基于降低的频率来建模，以更好地捕捉前缘涡流的动态。采用修正的有效迎角，包括俯仰分量，对瞬态力结果进行经验后缘分离修正。脉冲理论应用于DVM计算瞬态升力，并与CFD模拟进行了比较。结果表明，功率输出随着机翼厚度的增加而增加，并且在功率输出效率最高的较高折合频率处最为显着。
The energy harvesting performance of thick oscillating airfoils is predicted using an inviscid discrete vortex model (DVM). National Advisory Committee for Aeronautics (NACA) airfoils with different leading-edge geometries are modeled that undergo sinusoidal heaving and pitching with reduced frequencies,, in the range, wherefis the heaving frequency of the foil,cis the chord length, andis the freestream velocity. The airfoil pitches about the midchord with heaving and pitching amplitudes ofand, respectively, known to be in the range of peak energy harvesting efficiencies. A vortex shedding initiation criteria is proposed based on the transient local wall stress distribution determined from computational fluid dynamics (CFD) simulations and incorporates both timing and location of leading-edge separation. The scaled shedding times are shown to be predicted over the range of reduced frequencies using a timescale based on the leading-edge shear velocity and radius of curvature. The convection velocity of the shed vortices is also modeled based on the reduced frequency to better capture the dynamics of the leading-edge vortex. An empirical trailing-edge separation correction is applied to the transient force results using the effective angle of attack modified to include the pitching component. Impulse theory is applied to the DVM to calculate the transient lift force and compares well with the CFD simulations. Results show that the power output increases with increasing airfoil thickness and is most notable at higher reduced frequencies where the power output efficiency is highest.