First Grant Scheme: Boundary-layer transition on rotating bodies

第一个资助计划：旋转体的边界层转变

• 批准号: EP/G061637/1
• 负责人: Stephen Garrett
• 金额: $ 33.13万
• 依托单位: University of Leicester
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2009
• 资助国家: 英国
• 起止时间: 2009 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=EP%2FG061637%2F1
• 关键词: First; Grant; Scheme; Boundary; layer

Background: The rotating-disk boundary layer has long been used as a model for swept-wing flow because of the similarity between the basic-flow velocity profiles of the disk and the swept wing. However, continuing developments in spinning projectiles, aerofoils, aeroengines and other industrial applications has led to the need to understand the onset of laminar-turbulent transition of the boundary-layer flows over rotating disks, spheres and cones as objects in their own right.For example, rotating spheres and cones are used as nose cones in aeroengine and spinning projectile applications. Here laminar-turbulent transition within the boundary-layer flow over the nose cones can lead to significant increases in drag. For aeroengine applications this has negative implications for the fuel efficiency through increased noise and energy dissipation, and for projectile applications this has negative implications for control and accurate targeting. Understanding the stability of such boundary-layer flows and developing strategies to maintain laminar flow will lead to modifications in the design of these applications and enable significant cost savings. Furthermore, flows arising from rotating disks are present in types of chemical vapour deposition (CVD) reactors used for depositing thin films of optical and electrical materials on substrates in the electrochemical industry. Such reactors operate by forcing a carrier gas containing the reactive molecules onto the substrate held within a disk-like support placed horizontally in the flow. The gas flow can be considered as a uniform axial flow incident on a rotating disk and it is desirable that the flow close to the substrate be laminar and free from instability to ensure uniform deposition.Research: Experimental observations have noted a distinction between the transition region on slender and non-slender cones. For example, for cones with slender half-angles rotating in still fluid, pairs of counter-rotating Gortler-type vortices are observed. However, as the half-angle is increased beyond 30degs, the results clearly show that the vortices change from pairs of counter-rotating vortices to co-rotating vortices. It is well known that the vortices observed on rotating disks and non-slender cones are in fact co-rotating vortices attributed to an underlying crossflow instability, and so the observed instability for slender cones stems from an inherently different process. The existence of a viscous-mode dominated structure for slender cones which leads to the onset of a centrifugal Gortler instability has been hypothesised. It is this instability that will be studied in the research, with particular emphasis placed on the aerodynamic applications of rotating cones mentioned above.In addition, although the common assumption of an incompressible boundary-layer flow is reasonable for many aeroengine applications, it is not for the high-speed aerodynamic and CVD applications mentioned above. The studies performed so far on such boundary layers, although important in a theoretical context, must be considered as preliminary investigations with regards these applications. This research therefore also aims to study the effects of compressibility and heating on such bodies and the implications for machinery design.

工作背景：由于圆盘边界层和后掠翼的基本气流速度分布之间的相似性，圆盘边界层长期以来一直被用作后掠翼流动的模型。然而，随着旋转弹丸、翼型、航空发动机和其他工业应用的不断发展，人们需要了解旋转圆盘、球体和圆锥体上边界层层流-湍流转捩的发生，例如，旋转球体和圆锥体在航空发动机和旋转弹丸应用中被用作头锥。在这里，头锥上方附面层内的层流-紊流转变可导致阻力的显著增加。对于航空发动机应用，这通过增加噪声和能量耗散而对燃料效率具有负面影响，并且对于射弹应用，这对控制和精确瞄准具有负面影响。了解这种边界层流动的稳定性和发展战略，以保持层流将导致这些应用程序的设计修改，并使显着的成本节约。此外，在电化学工业中用于在基板上沉积光学和电学材料的薄膜的化学气相沉积（CVD）反应器类型中存在由旋转盘产生的流动。这种反应器通过将含有反应分子的载气强制到保持在盘状支撑件内的衬底上来操作，所述盘状支撑件水平地放置在流中。气流可以被认为是一个均匀的轴向流入射在一个旋转的磁盘上，它是可取的，靠近基板的流动是层流和自由的不稳定性，以确保均匀deposition.Research：实验观察已经注意到细长和非细长锥体的过渡区之间的区别。例如，对于在静止流体中旋转的具有细长半角的锥体，观察到成对的反向旋转的Gortler型涡。然而，随着半角的增加超过30度，结果清楚地表明，涡从对反向旋转的涡到同向旋转的涡。众所周知，在旋转圆盘和非细长锥体上观察到的涡实际上是由潜在的横流不稳定性引起的同向旋转涡，因此，细长锥体上观察到的不稳定性源于一种本质上不同的过程。假设细长锥体存在粘性模态主导结构，导致离心Gortler不稳定性的发生。在研究中将研究的正是这种不稳定性，特别强调上述旋转锥的气动应用。此外，虽然不可压缩边界层流动的一般假设对于许多航空发动机应用是合理的，但它不适用于上述高速气动和CVD应用。到目前为止，对这种边界层进行的研究虽然在理论上很重要，但必须被认为是对这些应用的初步研究。因此，本研究还旨在研究压缩性和加热对此类机构的影响以及对机械设计的影响。

项目成果

Transition mechanisms over slender versus broad rotating cones

细长旋转锥体与宽大旋转锥体之间的过渡机制

• 发表时间: 2010
• 作者: Hussain, Z

The Centrifugal Instability of a Slender Rotating Cone

细长旋转锥体的离心不稳定性

• DOI: 10.1260/1748-3018.6.1.113
• 发表时间: 2012
• 期刊: Journal of Algorithms & Computational Technology
• 影响因子: 0.9
• 作者: Hussain Z

Vortex-Speed Selection within the Rotating-Disk Boundary Layer

• DOI: 10.1260/1748-3018.4.1.71
• 发表时间: 2010-03
• 期刊: Journal of Algorithms and Computational Technology
• 影响因子: 0.9
• 作者: S. Garrett

Global linear stability of the boundary-layer flow over a rotating sphere

• DOI: 10.1016/j.euromechflu.2014.02.012
• 发表时间: 2015
• 期刊: European Journal of Mechanics B-fluids
• 影响因子: 2.6
• 作者: A. Barrow;S. Garrett;N. Peake

Boundary-Layer Transition on Broad Cones Rotating in an Imposed Axial Flow

• DOI: 10.2514/1.j050021
• 发表时间: 2010-06-01
• 期刊: AIAA JOURNAL
• 影响因子: 2.5
• 作者: Garrett, S. J.;Hussain, Z.;Stephen, S. O.
• 通讯作者: Stephen, S. O.