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首页> 外文期刊>Bulletin of the American Physical Society >APS -70th Annual Meeting of the APS Division of Fluid Dynamics- Event - On The Persistence Of Turbulent Boundary Layer Drag Reduction Under Pulsed DC Plasma Actuation
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APS -70th Annual Meeting of the APS Division of Fluid Dynamics- Event - On The Persistence Of Turbulent Boundary Layer Drag Reduction Under Pulsed DC Plasma Actuation

机译：APS-流体动力学APS分部第70届年会-事件-脉冲直流等离子体驱动下湍流边界层减阻的持久性

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Experiments are reported which use a novel method of active flow control explicitly designed to intervene in Streak Transient Growth which was first postulated by Schoppa and Hussain (POF 1998, JFM 2002) as the dominant mechanism for the production of streamwise vortices in wall-bounded turbulent flows. The flow control method utilizes pulsed-DC plasma actuator arrays that are mounted flush with the wall in a ZPG turbulent boundary layer. A key finding of Schoppa and Hussain (1998) was the persistence of drag reduction for a finite time interval $T_M^+=T_Mu_au^2/u=O(10^3)$ after termination of near-wall actuation. This time scale ultimately governs the required streamwise stagger between successive actuators for a given drag reduction application. In the reported experiment the time scale $T_M^+$ is established in a ZPG TBL. Oil film interferometry is used to directly measure the local wall shear stress at several consecutive locations downstream of a pulsed-DC actuator array. In this manner, the spatial evolution of the local wall shear stress is obtained and contrasted for the controlled flow and non-actuated flows. Subsequently, the characteristic streamwise distance $Delta x propto U_e T_M$, over which local skin friction relaxes back to natural values is determined.
机译：据报道，实验使用了一种主动流动控制的新方法，该方法明确设计为干预条纹的瞬时生长，该方法首先由肖普帕和侯赛因（POF 1998，JFM 2002）提出，它是在有壁湍流中产生涡流的主要机制。流。流量控制方法利用脉冲直流等离子体致动器阵列，该阵列与ZPG湍流边界层中的壁齐平安装。 Schoppa和Hussain（1998）的一个关键发现是在近壁驱动终止后，在有限的时间间隔$ T_M ^ + = T_Mu_au ^ 2 / u = O（10 ^ 3）$中，减阻的持久性仍然存在。对于给定的减阻应用，该时间尺度最终决定了连续执行器之间所需的流向错位。在所报告的实验中，在ZPG TBL中建立了时间标度$ T_M ^ + $。油膜干涉仪用于直接测量脉冲直流执行器阵列下游几个连续位置处的局部壁切应力。以这种方式，获得了局部壁面剪应力的空间演化，并针对受控流和非致动流进行了对比。随后，确定特征流向距离$ Delta x原型U_e T_M $，在该距离上局部皮肤摩擦力恢复为自然值。

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