Emergence of small-scale mixing in a T-mixer

T 型混合机中小规模混合的出现

• 批准号: 511099203
• 负责人: Professor Dr. Marc Avila Canellas
• 金额: --
• 依托单位: Zentrum für angewandte Raumfahrttechnologie und Mikrogravitation (ZARM)
• 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/511099203?language=en
• 关键词: Emergence; small; scale; mixing; mixer

The efficient mixing of fluids is key in many applications in chemical, mechanical, environmental and aerospace engineering. Typical examples range from chemical reactors to combustion chambers, but also the dispersion of contaminants in the ocean or atmosphere. The mixing rate is given by the surface of contact between the two fluids and the mass-diffusion coefficient. In most applications, turbulence sets the mixing rate, because eddies occurring at multiple scales strongly deform and convolute the surface between the fluids. In turbulence, the largest eddies are prescribed by the geometry, whereas the smallest possible eddies are found at the Kolmogorov scale. By contrast, the scalar concentration exhibits fluctuations down to the Batchelor scale, which in liquids is over an order of magnitude smaller than the Kolmogorov scale. As a consequence, in liquids, the small-scale properties of turbulent mixing remain poorly understood at a fundamental level, which prevents the scale-up of chemical reactions in many systems. In this proposal, mixing is experimentally investigated in a T-mixer setup with long inlets, which allow fully developed inflows. The mixing channel has a hydraulic diameter of four centimeters which results in a Batchelor scale of tenths of micrometers in the regime of interest. This will be resolved in the experiments with high-resolution laser-induced fluorescence. The research in this proposal will yield a better understanding of small-scale mixing in turbulence, and more specifically of how this emerges and is influenced by flow transitions as the Reynolds number increases.

在化学，机械，环境和航空航天工程中的许多应用中，流体的有效混合是关键。典型的例子范围从化学反应器到燃烧室，以及海洋或大气中污染物的分散。混合速率由两种流体和质量扩散系数之间的接触表面给出。在大多数应用中，湍流设置了混合速率，因为在多个尺度上发生的涡流强烈变形并在流体之间累积表面。在湍流中，最大的涡流是通过几何形状处方的，而最小的涡流是在Kolmogorov量表上发现的。相比之下，标量浓度表现出波动降低到批次尺度，在液体中，液体比Kolmogorov量表小的数量级。结果，在液体中，湍流混合的小规模特性在基本水平上仍然很少了解，从而阻止了许多系统中化学反应的扩展。在此提案中，在带有长入口的T-Mixer设置中对混合进行了实验研究，这允许完全发育的流入。混合通道的液压直径为四厘米，这导致了感兴趣的制度的十分之一微米的批度。这将在具有高分辨率激光诱导的荧光的实验中解决。该提案中的研究将更好地理解湍流中的小规模混合，更具体地说，随着雷诺数的增加，这是如何出现和受流动过渡的影响的。