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.

本文的目的是研究可压缩湍流边界层中微吹气减阻的概念。这似乎是合理的，因为最近对不可压缩流中均匀吹气的研究显示出非常有希望的减阻结果。然而，在不可压缩的情况下，可压缩的微吹是更加复杂和阻力的好处是不可预测的，因为表面摩擦分布也受到吹气体温度的巨大影响。此外，可压缩的情况下，受到更多的不确定性所造成的数值设置，这样一个非常仔细的处理是必要的，以获得可靠的参考数据。因此，所有目前的调查将通过直接数值模拟（DNS）的高性能计算机系统，提供有见地的数据，这是没有偏见的可能不适当的湍流模型。这将允许获得新的定性和定量的信息，极大的基础和实用价值。它已经显示在前两年半的先驱项目，我们的数值设置是能够提供可压缩的零压力梯度湍流边界层的一般情况下，这是独特的可靠性和科学相关性的杰出结果。本建议的第二个目的是继续这项基本工作，同时提供可压缩逆压梯度紊流边界层的可比较的参考数据，这是以下均匀吹气研究所需要的。由于数值装置已经在亚音速马赫数下对低马赫数逆压梯度情况进行了验证，这些结果可望提供与零压力梯度紊流边界层相同的精度，因此将引起科学界的极大兴趣。使用可压缩零压力梯度和逆压梯度基流，将研究和改进使用微吹的可压缩边界层控制的预测和建模，这可能是世界上第一次这样的DNS-对于可压缩问题，将获得验证大涡模拟和湍流模型的数据，包括研究变化的影响吹气温度和马赫数。还将与解析表达式进行比较。相关的研究在许多方面都是开创性的，并将为可压缩湍流边界层控制领域的流动物理提供新的和重要的基本见解，这将导致减少阻力，节省燃料和减少对环境的污染。