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

本文利用直接数值模拟方法，研究了冷等离子体激励器对三维边界层中横流诱导层流-湍流转捩的控制。三维边界层在后掠翼上是典型的，但在风力涡轮机的转子叶片上也是典型的，在转子叶片上，迎面而来的湍流水平高于在相对高的高度处的自由飞机飞行中。到目前为止，在壁面的吸力或微米级粗糙度元件的特殊设置已被研究并用于三维边界层的层流控制，但介质阻挡放电（冷）等离子体致动器可以更容易地操作，产生局部体积力延伸到边界层边缘。到目前为止，二维边界层的成功操作已经得到证实，但稳定和非稳定横流模式的控制，导致稳定或旅行横流涡是有前途的。基于对稳定模式的初步研究，本提案的主要目标是仔细检查等离子体致动器控制方案，包括由中等水平迎面湍流引起的行进模式，以检查这种控制对风力涡轮机叶片的基本适用性，以提高其效率。新的DLR-Göttingen Prinzip实验在这一阶段充当基流，以便稍后能够对数值结果进行直接的基本检验。

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.