风力机非对称钝尾缘翼型优化设计方法研究

Study of Optimization Design Method for Asymmetric Blunt Trailing-edge Airfoil of Wind Turbine

为了提高风力机钝尾缘翼型优化设计的精确性,提出设计变量计及尾缘厚度及其在中弧线上侧分配比的非对称钝尾缘翼型优化设计方法。采用风力机翼型型线集成理论和B样条曲线,建立钝尾缘翼型型线控制方程组。以翼型的形状函数系数、B样条控制参数以及钝尾缘厚度和其分配比为设计变量,利用粒子群算法耦合XFOIL软件进行钝尾缘翼型优化设计。针对S812翼型优化得到尾缘厚度2.61%c、厚度分配比0:1的钝尾缘改型,采用计算流体动力学方法研究翼型及其改型的气动性能和流场特性。结果表明:优化得到钝尾缘翼型的升力系数和最大升阻比均显著增大;钝尾缘翼型吸力面的气流在流场中发生下洗,改善了翼型表面压力分布,并引起翼型失速延迟,使得翼型的气动性能明显提高。

The optimization design method whose optimization variables include the trailing-edge thickness and its distribution ratio above the central arced curve is proposed to improve the design accuracy of the blunt trailing-edge airfoil. The parametric control equations of blunt trailing-edge airfoil profile are established using the profile integration theory of wind turbine airfoil and the B spline function. The optimization design model, taking the coefficients of airfoil shape function, the control parameters of B-spline function, and the blunt trailing-edge thickness and its distribution ratio as design variables, is established for the asymmetric blunt trailing-edge airfoil. The airfoil optimization is accomplished by employing the particle swarm optimization algorithm coupling with the software XFOIL. For S812 airfoil, the optimized blunt trailing-edge airfoil with the trailing-edge thickness of 2.61%c and the thickness distribution ratio being 0：1 is obtained. The aerodynamic performance and the flow characteristic of S812 airfoil and its modification are studied by the computational fluid dynamics method. The results indicate that after the blunt trailing-edge optimization, the lift coefficient and the maxinmm lift-drag ratio increase remarkably. The downwash effect in the flow field is produced by the suction surface airflow of blunt trailing-edge airfoil, which changes the pressure distribution on the suction and pressure surfaces and delays the stall flow over airfoil. So the aerodynamic performance of airfoil is improved obviously.