Inverse modal-decomposition method for complete determination of freestream disturbancesin supersonic flows

用于完全确定超音速流中自由流扰动的逆模态分解方法

• 批准号: 520690340
• 负责人: Professor Dr.-Ing. Rolf Radespiel
• 金额: --
• 依托单位: Lehrstuhl für Strömungslehre und Aerodynamisches Institut (AIA)
• 依托单位国家: 德国
• 项目类别: Research Grants
• 资助国家: 德国
• 项目状态: 未结题
• 来源: https://gepris.dfg.de/gepris/projekt/520690340?language=en
• 关键词: Inverse; modal; decomposition; method; complete

Wind tunnels are necessary to investigate laminar-turbulent transition of wall boundary layers for hypersonic vehicles, since these flows exhibit numerous physical flow phenomena that cannot be sufficiently accurate determined by numerical simulations at relevant Reynolds numbers. Wind tunnel tests, however, suffer from unavoidable disturbances in the test section flow, where generally acoustic waves, fluctuations of entropy, and vorticity fluctuations occur. These must be quantified over the relevant frequency range of the unstable boundary layers. The identification of the disturbances is an unsolved problem in hypersonics over the last 60 years, since there has been a lack of time-resolving measurement techniques, and the reduced physical models of wind tunnel disturbances could not be validated. By taking advantage of recent progress in time-resolving instruments for measuring pressure, velocity, and fluid density, and by using high-resolution flow simulations of a mid-size flow facility that represents world-wide state of the art, this important problem of hypersonic aerodynamics will be solved in this research project. The Institute of Aerodynamics of RWTH Aachen University will simulate the wind tunnel flow of the Hypersonic Ludwieg tube of the TU Braunschweig from the storage tube to the test section with all sources of freestream disturbances in the test section included. The computational results are used to extract and quantify the relevant disturbance modes in the test section. Highly resolved simulations of the flow over stagnation point probes in the test section will be used to determine appropriate probe geometries for identifying wave-speed directions. The Institute of Fluid Mechanics will perform Particle-Image Velocimetry to measure velocity fluctuations and Focussed Laser Differential Interferometry for density fluctuations with extensions and calibrations toward a resolution of 300kHz and to determine the measurement uncertainties. Combined with the findings of the new stagnation point probes the results will yield the acoustic modes, entropy modes, and vorticity modes by Bayesian Uncertainty Quantification. The results define future sound receptivity analyses of boundary layer behaviour in high-speed wind tunnels. The year-long numerical-experimental collaboration between Aachen and Braunschweig is the basis to successfully work on the challenging problem of modal decomposition in hypersonic flows.

风隧道对于研究高超音速车的壁边界层的层流扰动过渡是必要的，因为这些流动表现出许多物理流现象，这些现象无法完全准确地由相关雷诺数的数值模拟确定。然而，风洞测试在测试部分流动中不可避免地会受到不可避免的干扰，其中通常发生声波，熵的波动和涡度波动。这些必须在不稳定边界层的相关频率范围内进行量化。由于缺乏时间溶解时间的测量技术，因此在过去60年中，疾病的识别是在过去60年中无法解决的问题，而且无法验证风洞干扰的物理模型的减少。通过利用最新的时间解决工具的进展来测量压力，速度和流体密度，以及使用代表世界范围内最新技术状态的中型流动设施的高分辨率流量模拟，这项高超音速空气动力学的重要问题将在该研究项目中解决。 RWTH Aachen University的空气动力学研究所将模拟Tu Braunschweig的Hypersonic Ludwieg Tube的风洞流，从存储管到测试部分，其中包括测试部分中的所有自由式干扰来源。计算结果用于提取和量化测试部分中相关的干扰模式。测试部分中停滞点探头的流量的高度分辨模拟将用于确定用于识别波速方向的适当探针几何形状。流体力学研究所将执行粒子形象的速度计，以测量速度波动和聚焦激光差异干涉仪，以进行密度波动，并具有扩展和校准，朝分辨率为300kHz并确定测量不确定性。结合新停滞点的发现探测结果将通过贝叶斯不确定性定量产生声学模式，熵模式和涡度模式。结果定义了在高速风隧道中边界层行为的未来声音接受性分析。亚兴和布劳恩施威格之间为期一年的数值实验合作是成功解决高超音速流中模态分解问题的挑战性问题的基础。