Flow sensing, estimation and control in turbulent flows

湍流中的流量传感、估计和控制

• 批准号: RGPIN-2018-04147
• 负责人: Hall, Joseph
• 金额: $ 1.97万
• 依托单位: University of New Brunswick
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2022
• 资助国家: 加拿大
• 起止时间: 2022-01-01 至 2023-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=760187
• 关键词: Flow; sensing; estimation; control; turbulent

Turbulence is responsible for a significant portion of human energy consumption, for example, in fuel to overcome the drag on vehicles or the electricity required to pump fluids from place to place. It is now recognized that there are organized motions in seemingly random turbulent flows; these organized motions, or coherent structures, are critical to many quantities of engineering interest, like heat-transfer, drag, or noise production. The present research program aims to improve our understanding of how to manipulate these coherent structures to produce useful engineering results like enhanced heat-transfer, drag-reduction on vehicles, or reduced noise emissions. The proposed research program aims to improve our knowledge of how to manipulate the coherent structures in two flows, the three-dimensional wall jet and the flow over a backwards facing step. Whenever a jet is directed tangentially at a surface, a three-dimensional wall jet is formed. Three-dimensional wall jets occur frequently in heating and cooling applications, combustors, ventilation applications, as well as in coating processes. The three-dimensional wall jet strongly “sticks” to surfaces which causes the jet to spread and grow laterally outward along the wall 5 times greater than it grows perpendicular to the wall. Much of my previous research effort has gone into understanding how the turbulent coherent structures in the wall jet cause this behaviour. One of the goals of the proposed research is modifying the coherent structures in the wall jet so as to alter the surface coverage of the flow. Enhanced surface coverage would be beneficial in numerous heating and cooling applications and could be used to prevent flow separation and augment lift on aircraft wings (as a jet that “sticks” better to surfaces would be less prone to separate). Reduced surface coverage, on the other hand, would be useful in ventilation and combustion applications where higher levels of mixing are desired. The flow over a backwards facing step is the second flow targeted for developing flow control techniques. The flow over a backwards facing step is a simplified model of the flow separation process which occurs frequently on the rear of vehicles. Being able to control flow separation will reduce the drag on vehicles, thereby increasing fuel economy and reducing harmful emissions. As the turbulence created by flow separation processes is a source of noise within the vehicle, controlling flow separation will also create quieter vehicles. The proposed research will work towards the goal of separation control by first developing tools to estimate the instantaneous turbulent velocity field using wall based sensors.

湍流是人类能源消耗的很大一部分，例如克服车辆阻力所需的燃料或将流体从一个地方泵送到另一个地方所需的电力。现在人们认识到，看似随机的湍流中存在有组织的运动。这些有组织的运动或相干结构对于许多工程兴趣至关重要，例如传热、阻力或噪声产生，本研究计划旨在提高我们对如何操纵这些相干结构以产生有用的工程结果（例如）的理解。增强传热，拟议的研究计划旨在提高我们对如何操纵两个流动（三维壁射流和向后台阶上的流动）中的相干结构的了解。切向指向表面时，会形成三个强维壁射流，这在加热和冷却应用、燃烧器、通风应用以及涂层工艺中经常出现。到导致喷射的表面沿着墙壁横向向外扩散和生长的速度是垂直于墙壁生长的 5 倍，我之前的大部分研究工作都是为了了解壁射流中的湍流相干结构如何导致这种行为。正在修改壁射流中的相干结构，以改变流动的表面覆盖范围，增强的表面覆盖范围将有利于许多加热和冷却应用，并且可用于防止流动分离和增加飞机机翼上的升力（作为射流）。更好地“粘”在另一方面，减少表面覆盖对于需要更高水平混合的通风和燃烧应用是有用的，向后台阶上的流动是开发流动控制的第二个流动。向后台阶上的流动是车辆后部经常发生的流动分离过程的简化模型，能够控制流动分离将减少车辆的阻力，从而提高燃油经济性并减少有害排放。流动分离过程产生的湍流是噪声源在车辆内，控制流动分离也将创造更安静的车辆，所提出的研究将通过首先开发使用基于壁的传感器来估计瞬时湍流速度场的工具来实现分离控制的目标。