Active Control for Transition Delay of Two Dimensional Boundary Layers in In-Flight Experiments

减少飞机表面摩擦仍然是一个重要的经济和环境问题;然而，实现这种减少的主动方法仍然需要大量的研究和开发努力才能达到工业成熟。甚至关于最合适的概念、致动器或可实现的效率的非常基本的问题仍然是开放的讨论。正是在这种情况下，本项目提出了应用等离子体致动器调用过渡延迟在二维边界层，在实验室中，但特别是在飞行中。以前的研究已经证明了实现过渡延迟的两个基本原则;稳定的边界层，和主动波消除，这已被用于四种不同的操作模式。这些先驱实验中有许多是在简单的风洞实验中进行的;然而，该研究所的机动滑翔机也进行了非常复杂和复杂的飞行活动，证明了自然发生的过渡延迟。这一非常广泛的初步工作强调了等离子体作动器在飞机主动控制方面的巨大潜力。拟议的工作计划将复杂地交织在一起，在风洞中对平板和机翼剖面的一般构型进行理论、数值和实验研究，并在飞机上进行实际条件下的实验。边界层方程的数值解，连同实验确定的体力调用的等离子体致动器，允许理论稳定性分析，以协助配置致动器系统和阵列的能源效率的过渡延迟。这种预先的设计和优化，然后进行验证和改进，在风洞中使用平板实验。随后在全尺寸翼手套上进行风洞实验，然后可以直接进行飞行实验。分析等离子体致动器的功率，有效性和诱导力的新方法，然后将被用来评估各种操作模式的能量平衡方面，产生的整体效率的估计。这是为了提供一个直接的预测，如何可行的这种应用等离子体驱动是在未来。

Reduction of skin friction on aircraft remains an economic and environmental issue of importance; however, active methods to achieve such reductions still require significant research and development efforts to reach industrial maturity. Even very basic questions regarding the most appropriate concept, actuator or the achievable efficiency are still open for discussion. It is within this context that the present project proposes the application of plasma actuators to invoke transition delay in two-dimensional boundary layers, in the laboratory, but especially in-flight. Previous studies have demonstrated two basic principles for achieving transition delay; a stabilization of the boundary layer, and the active wave cancellation, which have been used in four different operating modes. Many of these precursor experiments have been conducted in simple wind tunnel experiments; however also very elaborate and intricate in-flight campaigns with the institute's motorized gliders have demonstrated delay of naturally occurring transition. This very extensive preliminary work underlines the enormous potential of plasma actuators for active control on aircraft.The proposed work program intricately interweaves theoretical, numerical and experimental studies of generic configurations of flat plates and wing profiles in wind tunnels with experiments under realistic conditions on aircraft. Numerical solutions of the boundary-layer equations, together with the experimentally determined body force invoked by the plasma actuators, allow a theoretical stability analysis to assist in configuring actuator systems and arrays for energy efficient transition delay. This up-front design and optimization is then to be verified and improved using flat plate experiments in wind tunnels. Subsequent wind tunnel experiments on a full-scale wing glove can then be directly followed by in-flight experiments. Novel approaches for analyzing the power, effectiveness and induced forces of plasma actuators will then be used to evaluate the various operating modes in terms of energy balance, yielding estimates of overall efficiency. This is intended to provide a direct prognosis of how viable this application plasma actuation is in the future.