Characterising Flow Regimes and Transitions, Heat Transport and Energy/Enstrophy Cascades in Rapidly Rotating Thermal Convection

表征快速旋转热对流中的流动状态和转变、热传输和能量/熵级联

• 批准号: EP/W022087/1
• 负责人: Peter Read
• 金额: $ 62.7万
• 依托单位: University of Oxford
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2023
• 资助国家: 英国
• 起止时间: 2023 至 无数据
• 项目状态: 未结题
• 来源: https://gtr.ukri.org/projects?ref=EP%2FW022087%2F1
• 关键词: Characterising; Flow; Regimes; Transitions; Heat

What is the problem?Turbulence driven by thermal convection is a ubiquitous process that occurs in many situations in both nature and in various technologies, ranging from the atmosphere and fluid interiors of planets (including the Earth) and stars through to industrial processes such as in chemical engineering, food preparation and power generation. When convection takes place in a rotating system, convection may radically change its character, developing coherent structures that align with the axis of rotation and significantly influence the efficiency by which heat, momentum and even mass are transported within the flow. Predicting how the strength of rotation and differential heating and cooling determine the flow and its transport properties and depend on other factors such as the shape of the system are especially difficult because of the complexity of the flow and the role of nonlinear feedbacks.Why is it important?Predicting the properties of rotating thermal convection is well known to be important in determining the shape and intensity of flows in the atmosphere, oceans and deep interior of the Earth, for example, influencing their climate and predictability. But it is also of major importance for the design of devices such as gas turbine engines used for aircraft propulsion and power generation. Strong temperature contrasts may develop between surfaces inside various rapidly rotating components of these engines that have been found to lead to complex convection patterns that significantly affect the transfer of heat within these components. As the designers of such engines attempt to improve their fuel efficiency and performance, manufacturing tolerances e.g. between turbine blades and their shrouds are becoming more and more demanding, requiring close control of temperatures throughout the engine under all operating conditions. It is vital, therefore, to improve our understanding of, and ability to model and predict, the structure and behaviour of the turbulent convection inside these engine systems and how it responds to changing conditions.What will this project achieve?This project seeks to improve our understanding of rotating convection under conditions that are similar to those found (a) inside rotating cavities within components of turbine engines and (b) in highly turbulent flows encountered in the atmospheres and interiors of rapidly rotating planets. We plan to construct a laboratory experiment that can generate turbulent convective flows inside a rapidly rotating cylindrical annular tank (i.e. the cavity between two co-rotating coaxial cylinders) by heating or cooling the inner and outer cylindrical walls. The cylindrical cavity can be rotated at different speeds about a vertical axis to include conditions that are either dominated by gravity acting in the vertical direction or by centrifugal forces acting in the radial direction. The latter are most relevant to conditions inside turbine engines or the convective fluid core of the Earth or other planets, while the former emulates the conditions found in planetary atmospheres or oceans. By conducting carefully controlled experiments over a broad range of rotation rate and thermal contrasts, we aim to determine how the flow changes in character from one regime to another and to quantify the impact of these changes on properties such as heat transfer and the formation of large-scale coherent structures such as vortices and zonal jets. This would be the first time both of these regimes would have been studied in the same experimental system, allowing us to gain new insights and understanding of these flows drawn from the fields of engineering science and geophysics. We plan to compare our experimental results with numerical model simulations obtained by engineers at the Universities of Bath, Surrey and Oxford of air flows in systems similar to gas turbine engine cavities to help improve their ability to predict flow structure and behaviour.

问题是什么？由热对流驱动的湍流是一种普遍存在的过程，在自然界和各种技术的许多情况下都会发生，从行星（包括地球）和恒星的大气和流体内部到工业过程，例如化学工程、食品制备和发电。当对流发生在旋转系统中时，对流可能会从根本上改变其特征，形成与旋转轴对齐的相干结构，并显着影响流内传输热量、动量甚至质量的效率。由于流动的复杂性和非线性反馈的作用，预测旋转强度和差异加热和冷却如何决定流动及其传输特性并取决于系统形状等其他因素尤其困难。为什么会这样重要吗？众所周知，预测旋转热对流的特性对于确定大气、海洋和地球内部深处流动的形状和强度非常重要，例如影响它们的气候和可预测性。但它对于用于飞机推进和发电的燃气涡轮发动机等设备的设计也非常重要。这些发动机的各种快速旋转部件内部的表面之间可能会产生强烈的温度对比，这会导致复杂的对流模式，从而显着影响这些部件内的热传递。当此类发动机的设计者试图提高其燃油效率和性能时，制造公差例如涡轮叶片与其护罩之间的温度要求越来越高，需要在所有运行条件下密切控制整个发动机的温度。因此，提高我们对这些发动机系统内部湍流对流的结构和行为以及它如何响应不断变化的条件的理解以及建模和预测的能力至关重要。该项目将实现什么目标？该项目旨在改进我们对旋转对流的理解类似于（a）涡轮发动机部件内的旋转腔内和（b）快速旋转行星的大气和内部遇到的高度湍流的条件。我们计划构建一个实验室实验，通过加热或冷却圆柱形内壁和外圆柱形壁，可以在快速旋转的圆柱形环形罐（即两个同向旋转的同轴圆柱体之间的空腔）内产生湍流对流。圆柱形空腔可以绕垂直轴线以不同的速度旋转，以包括由沿垂直方向作用的重力或由沿径向方向作用的离心力主导的条件。后者与涡轮发动机或地球或其他行星的对流流体核心内的条件最相关，而前者则模拟行星大气或海洋中的条件。通过在广泛的旋转速率和热对比范围内进行仔细控制的实验，我们的目标是确定流动特性如何从一种状态变化到另一种状态，并量化这些变化对传热和大颗粒形成等特性的影响。尺度相干结构，例如涡流和纬向射流。这将是第一次在同一个实验系统中研究这两种流态，使我们能够从工程科学和地球物理学领域获得对这些流的新见解和理解。我们计划将我们的实验结果与巴斯大学、萨里大学和牛津大学的工程师对类似于燃气涡轮发动机腔的系统中的气流进行的数值模型模拟进行比较，以帮助提高他们预测流动结构和行为的能力。

项目成果

The Dynamics of Jupiter's and Saturn's Weather Layers: A Synthesis After Cassini and Juno

木星和土星天气层的动力学：卡西尼号和朱诺号之后的综合

• DOI: http://dx.10.1146/annurev-fluid-121021-040058
• 发表时间: 2024
• 期刊: Annual Review of Fluid Mechanics
• 影响因子: 27.7
• 作者: Read P

Noise induced effects in the axisymmetric spherical Couette flow.

轴对称球形库埃特流中的噪声诱导效应。

• DOI: http://dx.10.1098/rsta.2022.0124
• 发表时间: 2023
• 期刊: Philosophical transactions. Series A, Mathematical, physical, and engineering sciences
• 作者: Krivonosova O