High Fidelity, Multiscale Modeling For Eco-Design in Aviation

拟议的研究计划大体上旨在为生态友好型航空开发预测性、多尺度模型和高保真设计工具。减少对环境的影响，同时保持经济盈利能力，可能是航空航天和运输行业以及能源部门面临的最重大的技术挑战。 对排放水平的日益严格的限制要求开发革命性的技术。计算工具对于这些新技术的设计将是非常重要的。 总体和长期目标是为创新和非传统设计做出贡献，以减少飞机噪音和发动机污染物。在短期内，拟议的计划重点是在非结构化网格解算器上引入多尺度、唯象模型和高保真计算工具，以预测飞机噪音和燃烧副产物，如二氧化碳、CO、NOx和烟尘。这些模型是专门为反应和非反应流动的大涡模拟(LES)而开发的。 在短期内，研究计划将专注于开发准确的和数学上一致的模型，以及特别适合在非结构网格解算器中实施的数值方案。非结构化网格允许极大的灵活性来表示复杂的工业类型几何图形。然而，许多精确子网格模型，如近似反褶积模型，仅适用于结构网格。非结构网格模型的推广和验证是本程序的主要目标之一。 从长远来看，这项研究将致力于利用所开发的计算工具，进一步深入了解在污染物和噪声的形成和辐射方面，相干结构在湍流中的作用。我们的假设是，湍流涡旋拓扑结构的变化对湍流剪切流的声辐射和湍流反应流中污染物的形成有重要影响。因此，人们可以通过使用适当设计的喷嘴和混合器来智能地改变湍涡的拓扑结构来控制和抑制噪音和污染物的形成。 我们将使用代数拓扑学和纽结理论等数学工具对湍流反应和非反应流动的直接数值模拟(DNS)和大涡模拟(LES)的结果进行后处理，以深入了解湍涡拓扑的作用。研究结果可望为湍流、计算气动声学和湍流燃烧等领域的新的拓扑理论和模型奠定基础。预计该项目还将为灰微喷嘴和波瓣混合器等噪声抑制装置的有效设计方法以及低排放燃烧室的新概念铺平道路。

The proposed research program broadly aims to develop predictive, multiscale models and high fidelity design tools for eco-friendly aviation. Reducing the environmental impact, while maintaining economic profitability, is perhaps the most significant technical challenge faced by aerospace and transportation industries, as well as the energy sector. The increasingly stringent restrictions on emission levels require the development of revolutionary technologies. Computational tools will be of significant importance for the design of such new technologies. The overarching and long-term goal is to contribute toward innovative and unconventional designs to reduce aircraft noise and engine pollutants. In the short term, the proposed program focuses on introducing multiscale, phenomenological models, and high fidelity computational tools on unstructured-grid solvers to predict aircraft noise and combustion byproducts such as CO2, CO, NOx, and soot. These models are in particular developed for Large Eddy Simulation (LES) of reacting and nonreacting flows. In the short term, the research program will be focused on developing accurate and mathematically consistent models, and numerical schemes that are specifically suitable for implementation in unstructured-grid solvers. Unstructured grids allow for significant flexibility to represent complex, industrial-type geometries. However, many accurate subgrid models such as Approximate Deconvolution Models have only be applied to structured-grids. The extension and verification of such models for unstructured grids is one of the main goals of this program. In the long term the research will be directed toward using the developed computational tools to obtain further insight into the role of coherent structures in turbulent flows with respect to the formation and radiation of pollutants and noise. Our hypothesis is that changes in the topology of turbulent eddies significantly affect sound radiation by turbulent shear flows and pollutants formation in turbulent reacting flows. Therefore, one can control and suppress noise and pollutants formation by intelligently changing the topology of turbulent eddies through the use of properly designed nozzles, and mixers. We will employ mathematical tools such as Algebraic Topology and Knot Theory to postprocess results from Direct Numerical Simulations (DNS) and LES of turbulent reacting and nonreacting flows to obtain insight about the role of turbulent eddies topology. The results are expected lay the foundation for new topological theories and models in turbulence, computational aeroacoustics, and turbulent combustion. It is also expected that this program would pave the path for effective design methodologies of noise suppression devices such ash microjets and lobed mixers, and new concepts for low-emission combustion chambers.