ERI: Experimental Investigation of Compressibility Effects on Turbulent Kinetic Energy Production in Supersonic Flows

ERI：压缩性对超音速流中湍动能产生的影响的实验研究

• 批准号: 2347416
• 负责人: Davide Vigano
• 金额: $ 20万
• 依托单位: Missouri University of Science and Technology
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2024
• 资助国家: 美国
• 起止时间: 2024-03-15 至 2026-02-28
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2347416&HistoricalAwards=false
• 关键词: ERI; Experimental; Investigation; Compressibility; Effects

Hypersonic flight offers the potential to revolutionize global travel and space exploration. A crucial technology for making this a reality is the development of efficient supersonic combustors for air-breathing hypersonic engines. These combustors differ from traditional ones in their extremely short residence times, typically around 1 millisecond. In such a short time, the fuel must be injected, vaporized (for liquid fuels), dispersed, and mixed to the molecular level with the incoming air before combustion can occur. Turbulence, which aids dispersion and mixing, is vital in this process. However, understanding how compressibility affects turbulence production is still incomplete, slowing down hypersonic flight development. This project aims to investigate compressibility effects on turbulence by directly measuring turbulence in the Mach 3 wind tunnel at Missouri University of Science and Technology. As turbulence plays a key role in the mixing process, understanding its production and how it is affected by compressibility would facilitate a better understanding of the mixing process in supersonic flows and the design of supersonic combustors.While turbulence production in supersonic flows has been recently investigated, compressibility effects – particularly on density fluctuations – have been largely neglected in non-wall-bounded flows such as jets and shear, which are relevant for mixing applications. Recent research indicates that even for the relatively low supersonic Mach number of a scramjet combustor (30-40% of the flight Mach), compressibility effects on turbulence production can be comparable to incompressible turbulence production. This analysis, based on theoretical arguments and limited experimental/numerical data from the available literature, indicates that the Strong Reynolds Analogy (a correlation between velocity and density fluctuations), initially developed for boundary layers, is also valid for unbounded supersonic mixing flows. This project proposes to experimentally verify the validity of the Strong Reynolds Analogy in a supersonic mixing unbounded flow by directly measuring density and velocity fluctuations utilizing two-point Focused Laser Differential Interferometry (2-FLDI). 2-FLDI is a proven low-cost technique that allows high-frequency, simultaneous, non-intrusive measurements of density and velocity fluctuations. The flow will consist of a simple planar jet from a pylon injector in a Mach 3 free stream. This work will also support STEM outreach through the development of a summer camp, and workforce development in hypersonics by supporting both graduate and undergraduate students. Findings from this work will also be incorporated into a graduate class on turbulent flows.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

高超音速飞行具有彻底改变全球旅行和太空探索的潜力，实现这一目标的一项关键技术是开发用于吸气式高超音速发动机的超音速燃烧器。这些燃烧器与传统高效燃烧器的不同之处在于其停留时间极短，通常约为 100 小时。在如此短的时间内，燃料必须被喷射、汽化（对于液体燃料）、分散并与进入的空气混合至分子水平，然后才能发生湍流，有助于分散和混合，在此过程中至关重要。然而，对压缩性如何影响湍流产生的了解仍然不完整，这减缓了高超音速飞行的发展。该项目旨在通过直接测量马赫数风洞中的湍流来研究压缩性对湍流的影响。由于湍流在混合过程中起着关键作用，了解其产生以及它如何受压缩性影响将有助于更好地理解超音速流中的混合过程和设计。虽然最近研究了超音速流中的湍流产生，但在与混合应用相关的非壁面流动（例如射流和剪切）中，压缩性效应（尤其是密度波动）在很大程度上被忽略了。即使对于超燃冲压发动机燃烧室相对较低的超音速马赫数（飞行马赫数的 30-40%），可压缩性对湍流产生的影响也可以与不可压缩性影响相媲美该分析基于理论论证和现有文献中有限的实验/数值数据，表明最初为边界层开发的强雷诺类比（速度和密度波动之间的相关性）对于无界超音速混合也有效。该项目建议通过利用两点聚焦激光差分干涉测量法 (2-FLDI) 直接测量密度和速度波动，通过实验验证超音速混合无界流中强雷诺类比的有效性。 2-FLDI 是一种经过验证的低成本技术，可以对密度和速度波动进行高频、同步、非侵入式测量。 这项工作由来自塔架喷射器的简单平面射流组成，速度为 3 马赫。还将通过举办夏令营来支持 STEM 推广，并通过支持研究生和本科生来支持高超音速领域的劳动力发展。这项工作的结果也将纳入关于湍流的研究生课程中。该奖项由 NSF 授予。法定使命，并通过使用基金会的智力价值和更广泛的影响审查标准进行评估，被认为值得支持。