基于N-S方程和自由转捩预测耦合求解的钝后缘翼型气动性能计算

Computational aerodynamic analysis of thick flatback airfoils coupling RANS and transition prediction code

大厚度钝后缘翼型由于结构和气动性能上的优点,被用于作为大型风力机叶片设计的内侧翼型。而由于其大厚度的特点和风洞实验阻塞度的限制,大雷诺数的风洞实验数据很少,给此类翼型的设计和使用带来困难。本文基于雷诺平均Navier-Stokes(RANS)方程和自由转捩预测耦合求解方法,进行了大厚度钝后缘翼型的气动性能计算研究;针对由于钝后缘后的涡脱落而造成的翼型表面压力分布的脉动,发展了有时均效应的转捩模型以考虑这种周期脉动的时均效应,并对传统的耦合求解方法进行了修改。通过对风力机翼型DU97-W-300的钝后缘改形DU97-Flat翼型的气动性能计算,分析了网格数对计算结果和计算效率的影响。并将计算的DU97-W-300翼型的气动性能和实验结果进行了比较,表明通过本文发展的耦合求解方法可以在更少的计算网格时得到比参考文献更吻合风洞实验结果的气动性能,为此类翼型的设计和使用提供数值计算基础。

The flatbact（blunt trailing edge） airfoils are adopted for the inboard region of large wind turbine blades due to their structural and aerodynamic performance advantages.Very limited experimental data at high Reynolds numbers makes it difficult for wind turbine designers to design and use these section shapes because the wind tunnel experiments are limited by the Reynolds number and solid blockage.In this study,a 2-D Reynolds-averaged Navier-Stokes solver coupled with a transition prediction code based on en method is used to CFD calculation of blunt trailing edge airfoils.A new coupling structure with a time-accurate transition prediction model taking into accounting the unsteady flow as a result of the bluff-body vortex shedding is developed.An airfoil of DU97-Flat modified by DU97-W-300 airfoil for wind turbine application is calculated and effects of grid points are investigated.The aerodynamic performance indicators of DU97-W-300 are calculated and compared with Timmer′s wind tunnel experiment results.It shows that the indicators calculated from the method illustrated in this study agree much better to Timmer′s wind tunnel experiment results compared to other results from literature while with much less gird numbers.