Unsteady wave phenomena in high-speed compressible flows

高速可压缩流中的非定常波现象

• 批准号: RGPIN-2014-05427
• 负责人: Timofeev, Evgeny
• 金额: $ 1.75万
• 依托单位: McGill University
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2019
• 资助国家: 加拿大
• 起止时间: 2019-01-01 至 2020-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=680063
• 关键词: Unsteady; wave; phenomena; speed; compressible

The unifying theme of the proposed wide-scope research program is unsteady wave phenomena in high speed compressible flows. The key points here are high velocities, which make compressibility effects and wave-like nature of the phenomena under study prominent, and essential flow unsteadiness, which challenges researchers and is much less studied as compared to relevant steady gasdynamic flows. From the physico-mathematical point of view all these fluid phenomena are described by so-called hyperbolic systems of conservation laws, making it possible to treat, within the same framework of mathematical models and computer codes, the phenomena which at first superficial glance do not have much in common. **In this spirit, the program encompasses four major research directions: (I) Fundamentals of essentially unsteady shock wave reflections from curved surfaces and transitions between different types of reflection: a number of issues related to physical mechanisms of these phenomena and interpretations of experimental observations have recently become a hot and contentious topic attracting many researchers; the proposed project is aimed at making crucial and decisive contributions to the debate; (II) Starting of air intakes for next-generation hypersonic air-breathing engines (scramjets): novel intake starting techniques based on unsteady effects (e.g., diaphragm-rupture induced) proposed earlier by the principal investigator will be further studied with more realistic models aiming at finding the ways of their practical implementation; an in-depth study and optimization of the widely used overboard spillage technique will be undertaken as well; (III) Shock wave phenomena in complex media as encountered in two application areas: the implosion-driven hypervelocity launcher for ground-based testing of orbital debris impact on satellites, and the shock wave propagation and cavitation bubble dynamics generated by laser pulse energy depositions in liquids as used in various medical applications of shock waves; (IV) Nonlinear magneto-acoustics: modelling of waves phase conjugation (time-reversal of acoustic signals) in heterogeneous media which has many applications in medical treatments and diagnostics, non-destructive testing and flow metrology. **The main research tool of the program will be the set of high-resolution and efficient flow solvers developed earlier by the principal investigator. These numerical methods and codes are planned to be further elaborated for more accurate, efficient and reliable treatment of the above problems. Furthermore, the principal investigator forged very close collaborative ties with, arguably, world leaders in experimental diagnostics for the four research directions mentioned above (from Australia, Canada, France, Japan), who would supply their experimental data and additionally perform experiments suggested and designed by the principal investigator. Such worldwide collaboration, in the true spirit of our era of globalization, would ensure that all three modes of investigation - theoretical, experimental and numerical - are used in the most effective combination within the proposed research program. **The major outcomes are expected to be discoveries of both fundamental and practical nature in the chosen research areas delivered to research and engineering community via refereed publications in archival journals; extensive training of graduate/undergraduate students in stimulating and in many aspects unique research environment, and further development of general computer codes for unsteady gasdynamics of shocked flows, which are already in use by many researchers worldwide and would undoubtedly serve as a solid base for future research undertakings and practical applications of their results.

拟议的大范围研究计划的统一主题是高速可压缩流动中的非定常波动现象。这里的重点是高速度，这使得所研究现象的可压缩性和波浪性突出，以及本质流动不稳定，这对研究人员构成了挑战，与相关的定常气动力流动相比，研究较少。从物理-数学的观点来看，所有这些流体现象都是由所谓的双曲守恒定律系统来描述的，这使得在相同的数学模型和计算机代码框架内处理乍一看没有太多共同之处的现象成为可能。**本着这种精神，该计划包括四个主要研究方向：(I)曲面上本质上不稳定的冲击波反射的基本原理和不同类型反射之间的过渡：与这些现象的物理机制和对实验观测的解释有关的一些问题最近成为吸引许多研究人员的热点和有争议的话题；拟议的项目旨在对这场辩论做出关键和决定性的贡献；(2)启动下一代高超声速吸气式发动机(超燃冲压发动机)的进气口：将用更现实的模型进一步研究主要研究者早先提出的基于非定常效应(例如，隔膜破裂)的新进气启动技术；还将对广泛使用的舷外溢流技术进行深入研究和优化；(3)在两个应用领域中遇到的复杂介质中的冲击波现象：用于对轨道碎片撞击卫星进行地面测试的内爆驱动的超高速发射器，以及在冲击波的各种医疗应用中使用的激光脉冲能量沉积在液体中产生的冲击波传播和空化气泡动力学；(4)非线性磁声学：非均匀介质中波的相位共轭(声波信号的时间反转)的模拟，这在医疗和诊断、无损检测和流量计量方面有许多应用。**该计划的主要研究工具将是首席研究员早先开发的一套高分辨率和高效率的流动解算器。这些数值方法和程序计划进一步完善，以便更准确、高效和可靠地处理上述问题。此外，首席研究人员与上述四个研究方向(来自澳大利亚、加拿大、法国、日本)的实验诊断领域的世界领导者建立了非常密切的合作关系，他们将提供他们的实验数据，并另外执行首席研究人员建议和设计的实验。这种全球合作，本着我们这个全球化时代的真正精神，将确保所有三种调查模式--理论、实验和数字--在拟议的研究计划中得到最有效的结合。**主要成果预计将是通过档案期刊上的参考出版物向研究和工程界提供选定研究领域的基础性和实用性的发现；对研究生/本科生进行广泛的培训，以激励和在许多方面建立独特的研究环境，并进一步开发用于激波流动的非定常气体动力学的通用计算机代码，这些代码已经被世界各地的许多研究人员使用，无疑将成为未来研究工作和其成果的实际应用的坚实基础。