An analytical model for airfoil aerodynamic characteristics over the entire 360° angle of attack range
An analytical model for airfoil aerodynamic characteristics over the entire 360° angle of attack range
复制标题
整个360°迎角范围内翼型气动特性的分析模型
DOI：
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发表时间：
2020
期刊：
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通讯作者：
V. K. Truong
中科院分区：
文献类型：
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作者：
V. K. Truong
风力涡轮机的设计需要快速准确地评估气动载荷。基于计算流体动力学（CFD）的高保真方法被认为是最有前途的，但仍然昂贵的空气动力学预测。仍然必须使用低或中等保真度的方法，这些方法强烈依赖于360°极化的知识。通过风洞测量或计算流体动力学（CFD）技术，可以在小的迎角范围内精确地预测出极角，直到超过失速临界角几度;这个迎角范围用Dms表示。对于较大的迎角值，在深失速区Dds，三维效应起着重要的作用，精确的极坐标的确定仍然具有挑战性。本文提出了Dms和Dds范围内力系数的半经验模型，并在两者之间进行了适当的过渡。对于射程Dds，建模是基于假定近似平板特性和力系数相对于迎角的某些对称特性。模型方程的参数是根据与翼型几何特征相关的翼型选定实验的分析确定的。对于射程Dms，提出了Beddoes-Leishman动态失速模型的修正公式。该模型已在两种翼型NACA 643-618和DU 97-W-300上成功进行了试验。详细描述整个迎角范围内的极线的新方法为动态失速模型的应用提供了基础。
The design of wind turbines requires rapid and accurate evaluation of aerodynamic loads. High-fidelity methods based on Computational Fluid Dynamics (CFD) are considered as most promising but remain expensive for predictions of aerodynamics. It is still imperative to use low or medium-fidelity methods that depend strongly on the knowledge of 360° polars. Polars can be accurately predicted by wind tunnel measurements or CFD techniques in the range of small values of AoAs up to a couple of degrees beyond the critical angle of stall; this AoA range is denoted by Dms. For higher values of AoAs, in the deep stall regime Dds, 3D effects play an important role and the determination of accurate polars is still challenging. This paper presents a semi-empirical model of force coefficients for both ranges Dms and Dds, with an appropriate transition between the two. For the range Dds, the modeling is based on assuming a nearly flat plate behavior and some symmetry properties for the force coefficients with respect to the angle of attack. The parameters of the model equations are determined from the analysis of selected experiments on airfoils associated with the characteristics of the airfoil geometry. For the range Dms, a modified formulation of the dynamic stall model of Beddoes–Leishman has been proposed. The model has been tested successfully on two airfoils, NACA 643-618 and DU97-W-300. The new approach of elaborating the polars for the whole range of AoAs provides a foundation for the application of a dynamic stall model.