高超声速进气道锯齿形转捩片的机理与验证

In recent years, boundary layer transition problem has attracted more attention in the research of the air-breathing hypersonic vehicle. It is found that it is difficult to achieve natural transition for hypersonic inlet boundary layer in flight. To obtain turbulence in the front of inlet entrance, artificial transition must be adopted, reducing or eliminating flow separation caused by shock / boundary layer interaction and enhancing the mixing of fuel and air in the combustion. Therefore, various shaped vortex generator has been investigated. It shows that vortex generator is effective for boundary layer transition but brings strong disturbance to the flow, decreasing inlet performance and facing the problems of aerothermodynamics at the same time. Therefore, it is necessary to explore the artificial transition device with low drag and high efficiency... In the study, the flow mechanism of triggering hypersonic boundary layer transition will be investigated by theoretical analysis and experimental verification for a sawtooth shaped transition device with low drag and high efficiency. Through the study, the flow mechanism will be revealed and the scope of its application will be expanded, theoretical and practical basis can also be obtained for better application in the future... Application requirements are clear in the study. Not only the theory research achievement but also the quantitative regular data can be achieved through the study.Therefore, this project has the characteristics and innovation.

近年来，边界层转捩问题在吸气式高超声速飞行器的研究中受到了高度重视。在实际飞行中发现高超声速进气道前体边界层难以实现自然转捩，必须通过人工转捩才能在进气道入口前获得湍流，通过湍流弱化或消除激波/边界层干扰导致的流动分离，增强燃烧室内燃料和来流的混合。为此，人们研究了各种形状的涡流发生器。实践表明，涡流发生器在有效触发转捩的同时对流场带来了强干扰，造成进气道性能下降同时面临自身防热的问题。因此，有必要探索低阻高效的人工转捩装置。. 本项目针对一种具有低阻高效特点的锯齿形人工转捩薄片，从理论分析与试验验证两方面对其触发高超声速边界层转捩的机理开展研究，以期揭示其流动机理、拓展其使用范围，为未来更好地应用奠定理论与实践基础。. 本项目应用需求明确，通过研究，不仅可以获得理论研究成果，同时可提供定量的、可应用的规律性数据，因此具有特色与创新性。

近年来，边界层转捩问题在吸气式高超声速飞行器的研究中受到了高度重视。在实际飞行中发现高超声速进气道前体边界层难以实现自然转捩，必须通过人工转捩才能在进气道入口前获得湍流，通过湍流弱化或消除激波/边界层干扰导致的流动分离，以满足燃烧室对来流空气的需求。实践表明，常规的涡流发生器虽然能够有效促发流动转捩但同时会带来额外的气动阻力与气动加热，造成进气道性能下降。因此，本项目设计了一种具有低阻高效特点的锯齿形人工转捩薄片，齿高24mm，齿角在90度附近，厚度不超过当地边界层厚度的1/5，并从理论分析、数值计算分析与试验验证等方面对其触发高超声速边界层转捩的机理开展研究，揭示了其触发流动转捩的机理、拓宽了其使用范围。其中，稳定性分析结果表明，转捩片引起的流动最优扰动条纹结构可以显著使得边界层变得更不稳定，从而有效促进转捩提前发生，压缩拐角分离区附近的剪切层具有改变失稳波性质、加速流动失稳的作用；大涡模拟的数值计算研究表明，锯齿形转捩片能够有效触发三楔压缩面边界层转捩，且能够高效地触发进气道压缩拐角分离区的边界层转捩，同样也能够触发等熵压缩面的边界层流动转捩；风洞试验同样验证了锯齿形转捩片均能触发流动转捩的有效性。通过本项目的研究，对于锯齿形转捩薄片触发高超声速边界层的转捩机理有了更加深入的认识,建立了其设计准则，拓展其使用范围，为后续工程应用研究奠定了基础，为推进高性能的高超声速进气道的设计与应用提供了新的思路与方法。