Computational Aerodynamics for Aircraft Drag Reduction

为了减少运输飞机的阻力和二氧化碳排放，提出的研究计划包括计算流体动力学的算法开发，气动形状优化的算法开发，以及通过非常规飞机配置和主动流动控制来减少阻力的应用。***计算流体力学的算法发展集中在具有广义分部求和性质的有前途的高阶算子上。这包括张量积算子的进一步发展，以及适用于非结构化网格的新型多维算子，最近由申请人小组介绍。这些运算符与不连续Galerkin方法具有相似的性质，但是，由于它们不依赖于明确的基础，因此它们提供了灵活性，有望用于提高现代计算机体系结构的效率。***气动外形优化算法的发展主要集中在两个方面。第一种是基于自由变形的自适应几何控制，使优化算法能够修改设计空间以寻找最优几何形状。由于这使得优化能够朝着设计师没有预料到的方向发展，因此它开辟了通过优化发现新的空气动力学概念的可能性。该研究还将包括开发一种可靠而有效的方法，将层流-湍流过渡的预测纳入优化框架，从而使开发利用自然层流重要区域的飞机配置成为可能。***正在研究的非常规飞机配置包括申请人小组开发的混合翼体的一种变体，即升力机身配置，以及支柱支撑翼和箱形翼配置。重点将放在区域和单通道飞机上，前者是因为它与加拿大的相关性，后者是因为它是全球飞机的主导类别。这三种配置将通过气动外形优化和中等保真度结构模型进行优化，并包括内饰和静态裕度约束。为了提供参考，基线常规配置将以相同的方式进行优化。目标是进一步推进这些配置，并确定三种配置中哪一种最有希望用于区域和单通道级别。***最后，高阶方法将用于湍流的直接和大涡模拟，并应用于减少阻力的主动流动控制技术的开发。特别是，重点将放在合成射流驱动上，以控制湍流边界层外层的大型结构。

Motivated by the need to reduce the drag of transport aircraft and as a result their CO2 emissions, the proposed research program comprises algorithm development for computational fluid dynamics, algorithm development for aerodynamic shape optimization, and application to drag reduction via unconventional aircraft configurations and active flow control. *** The algorithm development for computational fluid dynamics is concentrated on promising higher-order operators having the generalized summation-by-parts property. This includes further development of tensor-product operators as well as novel multidimensional operators applicable to unstructured grids recently introduced by the applicant's group. These operators have similar properties to discontinuous Galerkin methods, but, as they do not rely on an explicit basis, they offer flexibility that hopefully can be exploited to improve efficiency on modern computer architectures.*** The algorithm development for aerodynamic shape optimization concentrates on two areas. The first involves adaptive geometry control based on free-form deformation that enables the optimization algorithm to modify the design space in search of the optimal geometry. Since this enables the optimization to go in directions not anticipated by the designer, it opens up the possibility of discovering novel aerodynamic concepts through optimization. The research will also include the development of a reliable and efficient methodology for incorporating prediction of laminar-turbulent transition within the optimization framework, thus enabling the development of aircraft configurations exploiting significant regions of natural laminar flow.*** The unconventional aircraft configurations under study include a variation of the blended wing-body developed in the applicant's group known as the lifting fuselage configuration, as well as the strut-braced wing and box-wing configurations. Emphasis will be on regional and single-aisle class aircraft, the former due to its relevance to Canada, the latter because it is the dominant class of aircraft globally. The three configurations will be optimized through aerodynamic shape optimization coupled with medium fidelity structural models and including trim and static margin constraints. A baseline conventional configuration will be optimized in an identical manner in order to provide a reference. The goal is to further advance these configurations and to identify which of the three is most promising for the regional and single aisle classes. *** Finally, the high-order methods will be utilized in direct and large-eddy simulations of turbulent flows applied to the development of active flow control techniques for drag reduction. In particular, the focus will be on synthetic jet actuation to control large structures in the outer layer of the turbulent boundary layer.