This paper investigates the flow characteristics and wind energy utilizations of H-type vertical axis wind turbine (VAWT) blade and its trailing-edge modification while having a certain camber to facilitate a greater understanding of the effects of airfoil’s trailing-edge thickness and relative camber. The geometric dimensions are designed for 100 W wind wheel with NACA0021 airfoil, whose trailing-edge thickness is 0.442%c (with c the chord length), and the simulation accuracy of the Computational Fluid Dynamics (CFD) approach is validated through comparing the calculated results of the Realizable k–e turbulence model with experimental data. The blunt trailing-edge optimization of NACA0021 airfoil is performed by taking the maximum lift-drag ratio as the optimization objective, but the wind energy utilization of wind wheel with the optimized airfoil decreases with the increase of the trailing-edge thickness. Thus, the airfoil NACA0021 is modified to a sharp trailing-edge airfoil, namely, NACA0021S, and the wind energy utilization increases slightly. The airfoil’s relative camber is then increased by making the middle arc line locate on the circumference of wind wheel, and the effects of the relative camber on the pressure and vorticity distribution, torque, and wind energy utilization are analyzed. The results indicate that after the relative camber increases, the positive and negative pressure region areas decrease for NACA0021 and NACA0021S airfoils, and so do the length and distribution of the wake, but the torque coefficient and wind energy utilization increase.

中文翻译：

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考虑外倾角效应的H型垂直轴旋转叶片后缘改型气动性能

本文研究了具有一定弯度的H型垂直轴风力涡轮机（VAWT）叶片及其后缘修改的流动特性和风能利用，以利于更好地了解翼型后缘厚度和相对弯度的影响。 . 几何尺寸为100W风轮设计，采用NACA0021翼型，后缘厚度为0.442%c（弦长为c），计算流体动力学（CFD）方法的仿真精度通过比较计算验证Realizable k-e 湍流模型与实验数据的结果。NACA0021翼型的钝后缘优化以最大升阻比为优化目标，但优化翼型的风轮的风能利用率随着后缘厚度的增加而降低。因此，将NACA0021翼型改造成后缘锋利的翼型NACA0021S，风能利用率略有提高。然后通过使中间弧线位于风轮圆周上来增加翼型的相对弯度，分析相对弯度对压力和涡量分布、扭矩和风能利用的影响。结果表明，在相对弯度增加后，NACA0021和NACA0021S翼型正负压区面积减小，尾流长度和分布减小，但扭矩系数和风能利用率增加。