Control of crossflow-induced laminar-turbulent transition in a 3-d boundary-layer flow using plasma actuators

利用直接数值模拟的方法，研究冷等离子体激励器控制三维边界层内横流诱导的层流-湍流转变。三维边界层在后掠翼上是典型的，在风力涡轮机的转子叶片上也是如此，在那里迎面而来的湍流水平高于在相对较高高度自由飞行的飞机。到目前为止，人们已经研究了壁面吸力或微米级粗糙元件的特殊设置，并将其用于三维边界层的层流控制，但介质阻挡放电(冷)等离子体激励器可以更容易地操作，产生延伸到边界层边缘的局部体积力。到目前为止，二维边界层已被证明是成功的，但控制定常和非定常横流模式导致定常或行进横流涡流是很有前途的。基于对定常模式的初步研究，本提案的主要目标是仔细研究包含由中层来袭湍流引起的行进模式的情景的等离子体激励器控制，以检查这种控制在风力涡轮机叶片上的基本适用性，以提高其效率。新的DLR-Göttingen Printzip实验在这一阶段充当基本流程，以便能够对数字结果进行后来的直接基本测试。

Investigations for the control of crossflow-induced laminar-turbulent transition in 3-d boundary-layer flows by cold plasma actuators are planned using direct numerical simulations. 3-d boundary layers are typical on swept-back wings, but also on rotor blades of wind turbines where the level of oncoming turbulence is higher than in free airplane flight at relatively high altitude. To date, suction at the wall or a special setup of micron-sized roughness elements have been investigated and used for laminar flow control of 3-d boundary layers, but dielectric barrier discharge (cold) plasma actuators can be more easily operated, producing a localized volume force extending up to the boundary-layer edge. Successful operation has been demonstrated for 2-d boundary layers so far, but the control of steady and unsteady crossflow modes leading to steady or travelling crossflow vortices is promising. Based on first investigations with respect to steady modes, the primary goal of this proposal is to scrutinize the plasma-actuator control of scenarios comprising travelling modes induced by medium-level oncoming turbulence, in order to check the fundamental applicability of such a control on wind-turbine blades to improve their efficiency. The new DLR-Göttingen Prinzipexperiment serves as base flow in this stage to enable a later direct fundamental testing of the numerical findings.