Numerical investigations of micro blowing in compressible turbulent boundary layers with zero and adverse pressure gradients in stream-wise direction

流向零压力梯度和逆压力梯度可压缩湍流边界层微吹的数值研究

• 批准号: 411492272
• 负责人: Professor Dr.-Ing. Ulrich Rist
• 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: 2018
• 资助国家: 德国
• 起止时间: 2017-12-31 至 2020-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/411492272?language=en
• 关键词: Numerical; investigations; micro; blowing; compressible

The purpose of the present proposal is to investigate the concept of micro-blowing for skin-friction drag reduction in compressible turbulent boundary layers. This appears justified because recent investigations of uniform blowing in incompressible flows have shown very promising drag-reduction results. However, in comparison to the incompressible case, compressible micro-blowing is much more complex and drag benefits are yet unpredictable, since the skin-friction distribution is also massively influenced by the blowing-gas temperature. In addition, the compressible case is subject to much more uncertainties caused by the numerical setup, such that a very careful treatment is necessary to obtain reliable reference data. Therefore, all present investigations will be performed via Direct Numerical Simulations (DNS) on a high-performance computer system that delivers insightful data which is not biased by a possibly inappropriate turbulence model. This will allow obtaining new qualitative and quantitative information of great fundamental and practical value.It has already been shown in the first two and a half years of a precursor project, that our numerical setup is capable of providing outstanding results for the generic case of a compressible zero-pressure-gradient turbulent boundary layer, which are unique in terms of reliability and scientific relevance. A second aim of this proposal is to continue this fundamental work by also providing comparable reference data for the compressible adverse-pressure-gradient turbulent boundary layer, which is needed for the following investigations with uniform blowing. Since the numerical setup already has been validated for low-Mach number adverse-pressure gradient cases at subsonic Mach numbers, these results are expected to provide the same level of accuracy as for the zero-pressure-gradient turbulent boundary layer and will therefore be of great interest for the scientific community.Using the compressible zero- and adverse-pressure gradient base flows, prediction and modeling of compressible boundary-layer control using micro-blowing will be investigated and improved, probably for the first time in the world such that DNS-data for validation of Large Eddy Simulations and turbulence models will be obtained for the compressible problem including investigations of the influence of varying blowing-gas temperature and Mach number. Comparisons with analytical expressions will also be performed. The related investigations are pioneering in many aspects and will provide new and important fundamental insight into the flow physics in the area of compressible turbulent boundary-layer control which will lead to drag reduction for fuel savings and minimizing pollution of the environment.

本提案的目的是研究可压缩湍流边界层中皮肤摩擦阻力减少的微吹式概念。这似乎是合理的，因为最近对不可压缩流中均匀吹的研究显示出非常有希望的拖拉结果。但是，与不可压缩的情况相比，可压缩的微功能更为复杂，而阻力益处却是无法预测的，因为皮肤摩擦分布也受吹气机温度的巨大影响。此外，可压缩的情况受到数值设置引起的更多不确定性的约束，因此需要非常谨慎的治疗来获得可靠的参考数据。因此，所有目前的研究将通过高性能计算机系统上的直接数值模拟（DNS）进行，该系统提供了有见地的数据，而这些数据并非可能不适合不适当的湍流模型。这将允许获得巨大基本和实用价值的新的定性和定量信息。它已经在前两年的前两年中显示了，我们的数值设置能够为可压缩的零压力范围驱动器层的通用案例提供出色的结果，这在可靠性和科学相关性方面是独一无二的。该提案的第二个目的是通过为可压缩的不良压力梯度湍流边界层提供可比的参考数据来继续这项基本工作，这是以下对均匀吹的研究所需的。由于在亚音速马赫数下已经对低模型不良梯度案例进行了验证数值设置，因此预期这些结果将提供与零压力梯度的湍流边界层相同的准确性，因此将对科学社区产生极大的兴趣，从而对科学社区产生极大的兴趣。可能是世界上首次为可压缩问题验证大型涡模拟和湍流模型的DNS-DATA，包括研究各种吹气机温度和MACH数量的影响。还将与分析表达式进行比较。相关的研究在许多方面都在开创性，并将为可压缩湍流边界层控制领域的流动物理学提供新的重要基本见解，这将导致减少燃料节省并最大程度地减少对环境的污染。