摘要
针对动态失速引起的风力机翼型气动性能恶化的问题,本文基于动网格和滑移网格技术,开展了大涡模拟数值计算研究,探索了非定常脉冲等离子体的动态流动控制机理.结果表明,等离子体气动激励能够有效控制翼型动态失速,改善平均和瞬态气动力,减小力矩负峰值和迟滞环面积.压力分布在等离子体施加范围内出现了负压"凸起",上翼面吸力峰值明显增大.脉冲频率和占空比这两个非定常控制参数对流动控制影响显著,无因次脉冲频率为1.5时等离子体控制效果较好,占空比为0.8时即可接近连续工作模式下的气动收益.翼型深失速状态,等离子体促使流动分离位置明显向后缘移动,抵抗了大尺度动态失速涡的发生,分离涡结构破碎耗散、重新附着,涡流影响范围减小;浅失速状态,等离子体激励具有较强的剪切层操纵能力,诱导了翼型边界层提前转捩,促进了与主流的动量掺混.等离子体气动激励诱导出前缘附近贴体翼面"涡簇",起到了虚拟气动外形的作用.不同尺度、频域的动态涡结构与等离子体气动激励的非线性、强耦合作用导致了气动力/力矩的谐波振荡.
In order to solve the problem of aerodynamic performance deterioration caused by dynamic stall, based on the dynamic grid and sliding grid technology, the large eddy simulation numerical calculation is carried out, and the dynamic flow control mechanism of unsteady pulsed plasma is explored. The results show that the plasma aerodynamic actuator can effectively control the airfoil dynamic stall, improve the mean and transient aerodynamic forces, and reduce the negative peak value of the pitch moment and the area of the hysteresis loop. The negative pressure "bulge" appears in the plasma application areas, and the peak suction of the upper airfoil surface increases obviously. The two unsteady control parameters, pulsed frequency and duty cycle, have significant influence on the flow control. When the dimensionless pulsed frequency is 1.5, the plasma control effect is better, and when the duty cycle is 0.8, it is close to the aerodynamic benefits under the continuous working mode. In the deep stall state: the plasma impels the flow separation position to move backward obviously, which resists the occurrence of large-scale dynamic stall vortices. The structure of the separation vortices is broken, dissipated and reattached to the airfoil by the plasma, and the influence area of the vortices is reduced.In the light stall state: the plasma actuator has strong ability to control the shear layer, which induces the transition of the airfoil boundary layer in advance and promotes the momentum mixing with the main flow. The "vortex clusters" near the airfoil leading edge induced by plasma actuation play a role of virtual aerodynamic shape. The harmonic oscillation of aerodynamic force/moment is caused by the nonlinear and strong coupling effect between the dynamic vortex structure with different scales and frequencies and the plasma aerodynamic actuation.
作者
张卫国
史喆羽
李国强
杨永东
黄明其
白云卯
Zhang Weiguo;Shi Zheyu;Li Guoqiang;Yang Yongdong;Huang Minqi;Bai Yunmao(School of Aeronautics,Northwestern Polytechnical University,Xi'an 710000,China;College of Aerospace Science and Engineering,National University of Defense Technology,Changsha 410073,China;Low Speed Aerodynamics Institute.China Aerodynamics Research and Development Center,Mianyang 621000,Sichuan,China)
出处
《力学学报》
EI
CSCD
北大核心
2020年第6期1678-1689,共12页
Chinese Journal of Theoretical and Applied Mechanics
基金
风雷青年创新基金(PJD20190003)
基础和前沿技术研究基金(PJD20190002)资助项目。
