振荡翼在非均匀流中的能量提取性能分析

ANALYSIS OF ENERGY EXTRACTION PERFORMANCE OF OSCILLATING FOIL IN NON-UNIFORM FLOW

为了解振荡翼在非均匀流场中的能量提取性能,利用Fluent求解非均匀流场中的绕二维振荡翼非定常、不可压缩Navier-Stokes方程。通过分析不同最大攻角（αmax）及相应运动参数在非均匀流场的能量提取及水动力性能发现：与均匀流相比,流速在垂直方向非均匀分布使水翼升力系数在一个周期的平均值提高,从而可改善水翼的能量提取性能。当水翼表面存在旋涡时,非均匀流影响旋涡的结构,使水翼的转矩系数出现较大差异。在最大攻角接近水翼的失速角（30°附近）时,非均匀流使水翼的时均功率系数提高,振荡频率越高,时均功率系数提高越明显。与流速在垂直方向的非均匀分布相比,流速在水平方向的随时间的波动造成水翼的水动力性能及能量提取性能有较大的波动。

In order to realize energy extraction performance of oscillating foil in non-uniform flow field, the Fluent is used to solve the unsteady and incompressible Navier-Stokes equations of two-dimensional oscillating foil in non-uniform flow filed. The energy extraction and hydrodynamic performance in the non-uniform flow field are realized through the analysis of different maximum angle of attack （crux） and corresponding motion parameters. Comparing with uniform stream, non-uniform distribution of flow speed in perpendicular direction can improve the average value of lift coefficient in one period so that the energy extraction performance of hydrofoil can be improved. When the vortex appears in the surface of hydrofoil, the non-uniform stream will affect the structure of vortex and make the hydrofoil torque coefficient different. When the maximum angle of attack is close to the stall angle of the hydrofoil （around 30~ ）, the non-uniform flow increases the time-average power factor of the hydrofoil. The higher the oscillation frequency is, the more obvious the time-average power coefficient increases. Compared with the non-uniform distribution of flow speed in vertical direction, the fluctuation of the flow speed in the horizontal direction with time causes great fluctuations in hydrodynamic performance and energy extraction performance of the hydrofoil.