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具有大纵横比的Rayleigh-Bénard流中的热量和动量传递的影响，即与高度相比的大横向尺寸（Γ = 25，20和10）。对于这些大的展弦比，湍流上层结构的典型横向尺寸是高度的2至3倍。时间演化非常缓慢，这使得长时间的观测成为必要。为此，将用光学测量技术对具有透明冷却板的充水Rayleigh-Bénard池中的流动进行实验研究，瑞利数在5×105到108的范围内。为了同时测量水平面内的速度和温度，热致变色液晶（TLC）将被用作立体粒子图像测速和体积粒子跟踪测速的示踪粒子。将根据TLC的颜色外观确定温度。目前实验的主要好处是其在很长时间跨度（长达数天）内的稳定性，这使得长时间测量具有高空间分辨率和高统计相关性。由于迄今为止只有短期的数值模拟是可用的长期演变的湍流超结构可以研究的第一次。该项目为优先方案内的其他项目提供数据，并从其他项目开发的数据分析技术中获益。