低速湍流边界层DBD控制机制

Flow Control Mechanism of DBD on Low-speed Turbulent Boundary Layer

介质阻挡放电(DBD)激励器具有重量轻、无运动部件、易用及响应快等优势,在流动控制应用中受到广泛关注。等离子体湍流边界层减阻是DBD流动控制诸多应用之一,但DBD湍流减阻机制还需进一步探究。文章通过试验研究来流速度为10 m/s时DBD激励对平板湍流边界层摩擦阻力的影响。试验使用油膜干涉法测量摩阻的变化,利用热线风速仪和粒子图像测速系统(PIV)得到边界层内速度分布。其结果显示,在等离子体激励的作用下,测得的壁面摩擦因数减小。等离子体激励通过减小边界层缓冲层和对数区的速度,减少雷诺切应力以及湍动能,抑制了相干结构的发展,从而达到减阻的效果。

Dielectric barrier discharge(DBD)actuator has the advantages of light weight,no moving parts,ease of use,and quick response,and have received extensive attention in flow control applications.Plasma turbulent boundary layer drag reduction is one of the many applications of DBD flow control,and the DBD turbulence drag reduction mechanism needs to be further explored.The effect of plasma actuator on the skin-frictional drag of turbulent boundary layer on a flat plate was investigated experimentally at an incoming velocity of 10 m/s.The oil film interferometry was used to measure the change of skin-friction,and the hot wire anemometer and particle image velocimetry(PIV)were used to obtain the velocity distribution in the boundary layer.The results indicate that under the action of the plasma actuator,the measured skin-friction coefficient decreases.Plasma excitation suppresses the development of coherent structures by reducing the velocity of the boundary layer buffer and the logarithmic region,reducing the Reynolds stress as well as the magnitude of the turbulent kinetic energy,which results in drag reduction.