Simulation of flow phenomena at the helicopter rotor with high accuracy

高精度模拟直升机旋翼处的流动现象

• 批准号: 245278630
• 负责人: Dr. Manuel Keßler
• 金额: --
• 依托单位: Institut für Aerodynamik und Gasdynamik (IAG)
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2013
• 资助国家: 德国
• 起止时间: 2012-12-31 至 2018-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/245278630?language=en
• 关键词: Simulation; flow; phenomena; helicopter; rotor

The global goal of the project is the improvement of aerodynamic and aeroacoustic simulation capabilities for the helicopter. Advanced numerics - in this case Discontinuous Galerkin discretisations of high order - have already proven successful in simpler generic problems, and the aim is now to bring their value together with the existing possibilities of established flow solver like FLOWer. In consequence, a new generation of technologically advanced simulation tools will emerge. Taking into account the specific features of current and future computing technology we want to establish new levels of accuracy, reliability and efficiency. Therefore it is to be expected, that additional and more problematic parts of the helicopter flight envelope like highly loaded or sideward flight or even tail shake conditions can be simulated successfully and so the vision of a "virtual first flight" comes closer than ever.In a previous part of the project new DES (Detached Eddy Simulation) models have been successfully implemented and validated. Furthermore, run times of the then existing DG flow solver have been reduced by nearly an order of magnitude, while maintaining and even improving parallel efficiency up to thousands of processors. In the currently proposed project these efforts shall be continued towards the simulation of the complex flow phenomena at the helicopter rotor.In order to reach that goal, the physical model and its formulation have to be extended to cover the highly instationary flow features of dynamic stall, which happens in forward flight at the retreating blade and may significantly influence the entire flow field. On the other hand, it is inevitable to handle the elasticity of the rotor blades, where their deformation retroacts on the aerodynamics. Therefore the movement and deformation of the meshes have to be considered and - using the Chimera technology of overlapping grids - the flow state between them exchanged. Although turbulence models in general as well as grid deformation and Chimera transfers are well established technology, their usage in high order discretisations has to be observed very closely and possibly some modifications may turn up as appropriate. Finally, the success of our accuracy improvements is to be evaluated not only in global values as thrust and power consumption, but also in the acoustic post processing of descent flight encountering BVI (blade vortex interaction) events.To sum it up, such novel tools shall help to answer challenging technical questions dependably with sufficient accuracy, in order to significantly extend the capabilities of established methods in the medium term.

该项目的总体目标是提高直升机的空气动力学和航空声学模拟能力。先进的数值-在这种情况下不连续Galerkin离散的高阶-已经证明了成功的简单的一般问题，现在的目标是把他们的价值与现有的可能性建立流动求解器，如FLOWer。因此，新一代技术先进的模拟工具将出现。考虑到当前和未来计算技术的具体特点，我们希望建立新的准确性，可靠性和效率水平。因此，可以预期的是，直升机飞行包线中更多的和更有问题的部分，如高载荷或侧向飞行，甚至是尾部抖动条件，都可以成功地模拟，因此“虚拟首飞”的愿景比以往任何时候都更接近。在该项目的前一部分，新的DES（分离涡模拟）模型已经成功实施和验证。此外，运行时间，然后现有的DG流求解器已减少了近一个数量级，同时保持，甚至提高并行效率高达数千个处理器。在目前提出的项目中，这些工作将继续进行，以模拟直升机旋翼处的复杂流动现象。为了达到这一目标，必须扩展物理模型及其公式，以涵盖动态失速的高度非定常流动特征，动态失速发生在前飞中的后退桨叶处，并可能对整个流场产生重大影响。另一方面，处理转子叶片的弹性是不可避免的，其中转子叶片的变形对空气动力学起反作用。因此，必须考虑网格的移动和变形，并使用重叠网格的Chimera技术，交换它们之间的流动状态。尽管湍流模型以及网格变形和嵌合体传输是成熟的技术，但必须非常密切地观察它们在高阶离散化中的使用，并且可能会出现一些适当的修改。最后，我们的精度改进的成功不仅要在推力和功耗等全局值中进行评估，而且要在下降飞行遇到BVI（叶片涡干扰）事件的声学后处理中进行评估。总之，这些新工具将有助于以足够的精度回答具有挑战性的技术问题，以便在中期内显着扩展现有方法的能力。