Experimental study of near-wall transport and structures in turbulent Rayleigh-Bénard convection

固体表面与周围流体之间的热传递是许多自然和技术流动中的主要过程。虽然这个过程的基本原理，通常被称为对流传热，已经被深入研究了一百多年，但这个过程还没有被理解。新的想法，例如Rayleigh-Bénard对流中的热传输与其他湍流中的动量传输之间的类比，可能有助于优化发电过程，提高对气候变化的理解和可预测性，或提高室内或乘客舱的热舒适性。“伊尔梅瑙桶”--一个世界性的独特设施--允许在高度湍流和良好控制的对流中以无与伦比的空间和时间分辨率进行测量。与合作伙伴在子项目RB-2的合作，它应该被研究和量化，如何相干结构有助于对流传热在墙上。利用粒子图像测速法或粒子跟踪测速法等成像流测量技术，应发现瑞利-贝纳德对流中的热传输与泰勒-库埃特和管流中的动量传输之间的类比。由于在子项目TC-1、2和RS-1中获得的实验室结果中，后一种模型实验可能会有明显更高的传输速率，2可能会直接转移到热对流在100瑞利数。

The heat transfer between a solid surface and a surrounding fluid is a major process in many natural and technical flows. Although the basics of this process, generally referred to as convective heat transfer, have been studied intensively for more than hundred years, this process is not yet understood. New ideas like e.g. the analogy between the heat transport in Rayleigh-Bénard convection and the momentum transport in other turbulent flows may contribute to optimize the process of power generation, to improve the understanding and the predictability of the climate change or to increase the thermal comfort in interiors or passenger compartments. The “Barrel of Ilmenau” - a worldwide unique facility - permits measurements with unrivalled spatial and temporal resolution in highly turbulent and well-controlled convection. In collaboration with the partners in subproject RB-2 it should be studied and quantified, how coherent structures contribute to the convective heat transfer at the wall. Using imaging flow measurement techniques like Particle Image Velocimetry or Particle Tracking Velocimetry analogies between the heat transport in Rayleigh-Bénard convection and the momentum transport in Taylor-Couette and in pipe flow should be found. Since significantly higher transport rates are possible in the latter model experiments in the lab results obtained in the subprojects TC-1,2 and RS-1,2 might be transferred directly towards thermal convection at ultrahigh Rayleigh numbers.