Simultaneous volumetric measurement of the velocity and temperature field in Rayleigh-Bénard cells with large aspect ratio

大纵横比瑞利-伯纳德池中速度场和温度场的同时体积测量

• 批准号: 429328691
• 负责人: Professor Dr.-Ing. Christian Cierpka
• 金额: --
• 依托单位: Technische Thermodynamik
• 依托单位国家: 德国
• 项目类别: Priority Programmes
• 财政年份: 2019
• 资助国家: 德国
• 起止时间: 2018-12-31 至 2023-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/429328691?language=en
• 关键词: Simultaneous; volumetric; measurement; velocity; temperature

The main objective of the project is to determine the influence of the turbulent superstructures on the heat and momentum transfer in Rayleigh-Bénard flows with large aspect ratios, i.e. large lateral dimensions in comparison to height (Γ = 25, 20 and 10). For these large aspect ratios the typical lateral dimensions of the turbulent superstructures are 2 to 3 times the height. The temporal evolution is very slow, which makes long-time observations necessary. For this reason the flow in a water filled Rayleigh-Bénard cell with transparent cooling plate will be experimentally investigated with optical measurement techniques for Rayleigh numbers in the range of 5×105 to 108. To simultaneously measure velocity and temperature in the horizontal plane, thermochromic liquid crystals (TLCs) will be used as tracer particles for stereoscopic particle image velocimetry and volumetric particle tracking velocimetry. The temperature will be determined based in the color appearance of the TLCs. The main benefit of the current experiment is its stability over very long time spans (up to days) which allows for long-time measurements with high spatial resolution and high statistical relevance. Since so far only short time numerical simulations are available the long term evolution of the turbulent superstructures can be investigated for the first time. The project serves as data provider for other projects within the priority programme and benefits from the development of data analysis techniques from other projects.

该项目的主要目标是确定湍流上层结构对大纵横比（即与高度相比横向尺寸较大（Г = 25、20 和 10））的瑞利-贝纳德流中的热和动量传递的影响。对于这些大的纵横比，湍流上部结构的典型横向尺寸是高度的 2 到 3 倍。时间演化非常缓慢，因此需要长时间观测。为此，将采用光学测量技术对带有透明冷却板的充水瑞利-贝纳德池中的流动进行实验研究，瑞利数范围为 5×105 至 108。为了同时测量水平面内的速度和温度，将使用热致变色液晶 (TLC) 作为示踪粒子进行立体粒子图像测速和 体积粒子跟踪测速。温度将根据 TLC 的颜色外观来确定。当前实验的主要好处是其在很长的时间跨度（长达数天）内的稳定性，这使得可以进行具有高空间分辨率和高统计相关性的长时间测量。由于迄今为止只能进行短时间数值模拟，因此首次可以研究湍流上层结构的长期演化。该项目作为优先计划内其他项目的数据提供者，并受益于其他项目的数据分析技术的开发。