Determining the Effects of Competing Instabilities in Complex Rotating Boundary Layers

确定复杂旋转边界层中竞争不稳定性的影响

• 批准号: EP/R028699/1
• 负责人: Zahir Hussain
• 金额: $ 24.21万
• 依托单位: Manchester Metropolitan University
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2018
• 资助国家: 英国
• 起止时间: 2018 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=EP%2FR028699%2F1
• 关键词: Determining; Effects; Competing; Instabilities; Complex

Fluid mechanics is of fundamental importance and underpins key developments in a range of disciplines, including aerospace, defence, energy and environmental research. For example, the efficient use of fuel has become an increasingly important factor in civil aviation, with the International Air Transport Association (IATA) committed to "reducing fuel consumption and CO2 emissions by at least 25% by 2020, compared with 2005 levels". Concurrently, aircraft engine noise has become a real and growing environmental issue, especially in the vicinity of airports around the world. Given the global demand for increased air travel, energy efficient and quieter aeroengines are important targets for the aviation and aerospace industries. Aerodynamic improvements have the potential to contribute to the design of the next generation of energy-efficient aeroengines and tubomachinery. Specifically, an increased understanding of the underlying physics through active flow control can reduce aerodynamic drag and delay the transition to unstructured, turbulent flow, both of which are known to have negative implications for fuel consumption and noise emissions. The goal of delaying turbulent-transition can be achieved in a cost-effective way through detailed numerical simulations, as opposed to comparatively expensive experimental investigations. This project will help to achieve that goal by applying a novel computational approach that can model flow within the boundary layer over complex rotating geometries.The boundary layer, a thin layer of fluid confining its viscosity close to a bounding surface, can influence the aerodynamics and drag characteristics of a fluid flow in a profound and significant way. Historically, the boundary layer flow over a rotating disk was used to model air flow over a swept-wing due to the similarity between their velocity profiles. Today, continuing developments in aeroengines, turbomachinery, spinning projectiles and, more recently, electrochemical applications, has created the need to understand boundary-layer flows over rotating bodies, such as disks, spheres and cones. Indeed, rotating 3D boundary-layer flows are now known to exhibit numerous flow characteristics, governed by highly complex and often competing mechanisms that cause flow instability and eventual breakdown to turbulent flow. For a family of rotating cones, experiments have observed a continuous change of flow characteristics as the governing flow parameters are altered. The applicant has shown that this change arises from an interaction between various forces governing flow within the boundary layer. However, the nature of this competing interaction remains largely unknown. With this in mind, this research project will develop a complex computational modelling code capable of providing robust and accurate quantitative predictions of the interaction between competing flow instability mechanisms in the turbulent-transition process. Such predictions can help to accelerate aerodynamics research, and inform or form part of innovative flow control strategies to reduce drag, thereby improving fuel consumption, as well as decreasing harmful noise and CO2 emissions.

流体力学具有根本性的重要性，支撑着一系列学科的关键发展，包括航空航天、国防、能源和环境研究。例如，燃料的有效利用已成为民用航空中越来越重要的因素，国际航空运输协会（IATA）承诺“到2020年，与2005年的水平相比，燃料消耗和二氧化碳排放量至少减少25%”。与此同时，飞机发动机噪音已经成为一个现实的、日益严重的环境问题，特别是在世界各地的机场附近。鉴于全球对航空旅行的需求增加，节能和更安静的航空发动机是航空和航天工业的重要目标。空气动力学的改进有潜力为下一代节能航空发动机和涡轮机械的设计做出贡献。具体来说，通过主动流动控制增加对底层物理的理解可以减少气动阻力，并延迟向非结构化湍流的过渡，这两种情况都对燃油消耗和噪音排放有负面影响。延迟湍流过渡的目标可以通过详细的数值模拟以经济有效的方式实现，而不是相对昂贵的实验研究。该项目将通过应用一种新颖的计算方法来帮助实现这一目标，该方法可以模拟复杂旋转几何形状的边界层内的流动。边界层是一层薄薄的流体，在边界表面附近限制其粘度，它对流体流动的空气动力学和阻力特性有着深远而重要的影响。从历史上看，旋转圆盘上的边界层流动被用来模拟后掠翼上的气流，因为它们的速度分布很相似。今天，航空发动机、涡轮机械、旋转弹丸以及最近的电化学应用的不断发展，使得人们需要了解旋转物体（如圆盘、球体和锥体）上的边界层流动。事实上，旋转三维边界层流动现在已知表现出许多流动特征，由高度复杂且经常相互竞争的机制控制，这些机制导致流动不稳定并最终分解为湍流。对于一类旋转锥，实验发现随着控制流参数的改变，其流动特性发生了连续的变化。申请人已经证明，这种变化是由控制边界层内流动的各种力之间的相互作用引起的。然而，这种竞争相互作用的本质在很大程度上仍然未知。考虑到这一点，本研究项目将开发一个复杂的计算模型代码，能够提供湍流过渡过程中竞争流动不稳定机制之间相互作用的可靠和准确的定量预测。这些预测可以帮助加速空气动力学研究，并为创新的流量控制策略提供信息或形成一部分，以减少阻力，从而提高燃油消耗，减少有害噪音和二氧化碳排放。

项目成果

Global stability analysis of axisymmetric boundary layer on a slender circular cone with the streamwise adverse pressure gradient

流向逆压梯度细长圆锥轴对称边界层整体稳定性分析

• DOI: 10.1016/j.euromechflu.2021.01.008
• 发表时间: 2021
• 期刊: European Journal of Mechanics - B/Fluids
• 作者: Bhoraniya R

Inviscid Modes within the Boundary-Layer Flow of a Rotating Disk with Wall Suction and in an External Free-Stream

壁吸力旋转盘边界层流和外部自由流中的无粘模

• DOI: 10.3390/math9222967
• 发表时间: 2021
• 期刊: Mathematics
• 影响因子: 2.4
• 作者: Al Saeedi B

Competing roughness effects on the non-stationary crossflow instability of the boundary-layer over a rotating broad cone

竞争粗糙度对旋转宽锥体边界层非稳态横流不稳定性的影响

• DOI: 10.1063/5.0105788
• 发表时间: 2022
• 期刊: Physics of Fluids
• 影响因子: 4.6
• 作者: Al-Malki M

On the stability of boundary-layer flow over a rotating cone using new solution methods

使用新的求解方法研究旋转锥体上边界层流的稳定性

• DOI: 10.1088/1742-6596/1909/1/012041
• 发表时间: 2021
• 期刊: Conference Series
• 作者: Hussain Z

Effects of the suction/injection and external free stream on the instability of a boundary layer over a rotating disk

抽吸/注入和外部自由流对旋转盘上边界层不稳定性的影响

• DOI: 10.1063/5.0137448
• 发表时间: 2023
• 期刊: Physics of Fluids
• 影响因子: 4.6
• 作者: Al Saeedi B