一种抑制大分离流动的被动控制方法

A Passive Control Method for Suppressing Large Separation Flow

改善叶片流动分离现象是提高叶轮机械安全性与运行效率的重要措施。受鸟类羽毛前缘失速时自适应弹起启发,提出一种布置于翼型吸力面前部的自适应气动弹片。以S809翼型为研究对象,采用数值模拟方法,结合SST k-ω湍流模型,研究气动弹片厚度、长度及角度对翼型增升减阻特性的影响,并基于功率谱方法分析非定常流场气动参数变化情况。结果表明:较之弹片厚度,弹片长度和角度是影响翼型气动性能的主要因素,且攻角越小、雷诺数越大,弹片增升减阻效果越佳;弹片翼型流动分离区域明显小于原始翼型,弹片减阻能力显著,前缘分离区域明显缩小;弹片可有效改善翼型前缘流动分离时的气动参数变化复杂性,增加流场稳定性;弹片使气动参数主频提高,功率谱密度峰值大幅降低,峰值数量减少,弹片翼型谱密度积分降低明显。

Improving the flow separation performance of the blade is an important measure to improve the safety and operating efficiency of turbomachine.Inspired by the adaptive springing of bird feathers when the leading edge stalls,an adaptive pneumatic flap arranged in front of the airfoil suction is proposed.With the S809 airfoil as the research object,the numerical simulation method and the SST k-ωturbulence model are used to study the influence of the thickness,length and angle of the aeroelastic flap on the airfoil′s lift increasing and drag decreasing characteristics.The variation of aerodynamic parameters in unsteady flow field is analyzed based on power spectrum method.The results show that the length and angle of the flap are the main factors affecting the aerodynamic performance of the airfoil compared with the thickness of the flap.The smaller the angle of attack and the larger the Reynolds number,the better the effect.The flap airfoil flow separation area is significantly smaller than the original airfoil,the flap′s drag reduction ability is significant,and the leading edge separation area is significantly reduced.The flap can effectively reduce the complexity of aerodynamic parameters variation and increase the flow stability when leading edge flow separation occurs.The flap increases the main frequency of aerodynamic parameters,greatly reduces the peak power spectral density,reduces the number of peaks and significantly reduces the integral of the flap airfoil spectral density.