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

固体表面和周围流体之间的热传递是许多自然流动和技术流动的主要过程。虽然这一过程的基本原理，通常被称为对流传热，已经被深入研究了一百多年，但这一过程尚未被理解。新的想法，如瑞利-巴姆纳德对流中的热量传递与其他湍流中的动量传递之间的类比，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，或增加室内或客舱的热舒适性。“伊尔曼瑙之桶”是一个世界范围内独一无二的设施，可以在高度湍流和控制良好的对流中进行无与伦比的空间和时间分辨率测量。与子项目RB-2的合作伙伴合作，应该研究和量化连贯结构如何促进壁面的对流换热。利用成像流测量技术，如粒子成像测速或粒子跟踪测速，可以发现瑞利-巴姆纳德对流中的热传递与泰勒-库埃特对流和管道流中的动量传递之间的类比。由于在子项目TC-1、2和RS-1中获得的实验室结果中，在后一种模式实验中可能有明显更高的输运率，因此可能在超高瑞利数下直接向热对流转移。

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.