射流技术对DU翼型气动性能影响的数值模拟

Numerical simulation with jet technology influence on the aerodynamic performance of DU airfoil

提出改善翼型气动特性的方法,可用于提升农用小型水平轴风力机的功率。使用计算流体力学的方法进行研究,选取风力机专用翼型DU91-W2-250建立二维前缘射流数值模型,采用适合外流场计算与混合流动的两方程湍流模型SST k-ω研究非定常与定常射流情形下翼型的气动性能。射流动量系数C_μ在0.004~0.025的范围区间内前者比后者有8.84%~67.88%的升力系数增量提升,但升力系数存在明显周期波动;非定常射流升力响应时间要明显长于定常射流升力响应时间,随Cμ上升前者增加22~365 ms的延迟,呈现非线性趋势,后者增加8~48 ms的延迟,呈现线性趋势。对流场定性分析指出,非定常射流对气流扰动作用更明显,翼型吸力面气流流动呈现周期特性;定常射流持续向翼型吸力面注入能量,升力系数增量维持比较稳定,在相同Cμ下前者大攻角气流分离抑制能力要高于后者,可显著改善翼型的失速特性。

Proposed a way to improve airfoil aerodynamic characteristics,be used to increase the power of small horizontal axis wind turbine. Using CFD method, the blade airfoil of DU91-W2-250 was selected to establish two-dimensional leading-edge unsteady gas jet numerical model, choosing two equations turbulence model SST k-ω that suitable for calculation outflow field and mixed flow to study leading edge unsteady gas jet aerodynamic characteristics. The results show that momentum coefficient of the jet C_μ on the range of 0.004~0.025, lift coefficient of the former is 8.84%~67.88% higher than that of the latter, But observed periodic fluctuation of the lift coefficient. The lift response time of unsteady jet is obviously longer than steady jet, with C_μ increased, the delay form 22~365 ms, showing anonlinear trend, the latter increased the delay by 8~48 ms, showing a linear trend;qualitative analysis of the flow field indicates unsteady jet flow has more obvious effect on flow disturbance,airflow on airfoil suction surface presents periodic characteristics. the steady jet continuously injects energy into the airfoil suction surface, lift coefficient increment maintains relatively stable;at same C_μ, the separation and inhibition ability of the former is higher than that of the latter, the stall characteristic of airfoil can be improved remarkably.