Experimental studies and control of wall-bounded and separated shear layers using active flow control

商业航空对环境的影响是严重、广泛和持久的。机场附近的地区在起飞和降落时会受到噪音污染。燃烧喷气燃料产生的排放物会导致空气污染，几十年来，气候变化：根据IPCC的数据，商业航空产生的人类对全球变暖的贡献占4.9%。国际航空运输协会（IATA）的政策是到2020年实现商业航空的碳中和增长，到2050年将二氧化碳排放量减少50%。减少对环境的影响是未来飞机设计的关键挑战。为了使加拿大航空航天业每年产生236亿美元的收入，保持全球竞争力，需要在技术上进行逐步变革。其中一项技术是主动流动控制，欧洲航空研究咨询理事会已将其确定为生产满足航空航天工业严格环境目标所需技术的一个关键因素。拟议的研究是针对开发和实施新的主动流量控制策略，重点是流场，是相关的加拿大航空航天工业。它将集中在边界层过渡，作为控制湍流边界层和剪切层分离的先驱。这些流动的重要性与它们在广泛的工程系统中对阻力和噪声产生的影响有关。值得注意的是，由于湍流边界层的表面摩擦阻力是10倍以上的等效层流边界层。在分离的情况下，产生的尾流和周期性流动结构导致不希望的压阻和波动的气动载荷。湍流边界层和分离的剪切层都是噪声排放增加的原因。因此，延迟转捩、控制湍流和管理分离流可以显著降低阻力和噪声排放。所提出的方法是利用基本的流动动力学和不稳定性来开发有效的闭环控制器。这一方面与传感器和执行器的发展密切相关，以实现控制系统。这些控制系统将在实验框架中实施和测试。因此，研究不仅限于流体流动及其控制的研究，而且还解决了与真实的生活中的主动流动控制应用相关的关键实际挑战。** 这项研究的实际影响是广泛的。它们包括在各种商业相关流体系统中减少阻力、燃料消耗和噪音排放。这些好处将减少我们对化石燃料的依赖，减少温室气体排放。拟议的工作是多学科的，因为它借鉴了流体动力学，反馈控制和动力系统领域的专业知识。它也是变革性的，因为它解决了一些悬而未决的问题，从长远来看，这些问题不仅会导致与能源转换设备和运输有关的流体流动管理的工程实践的范式转变，而且还会导致这些工程系统的能源效率设计实践的范式转变。拟议的研究将涉及2名博士，3名硕士和5名本科生。这些学生将获得在加拿大的许多技术部门，特别是航空航天业的高需求的技能和专业知识。加拿大公司，如庞巴迪航空航天公司和普惠加拿大公司将直接受益于拟议的研究和高素质的人才，它将培训。

The impacts of commercial aviation on the environment are serious, widespread and long-lasting. Areas near airports are subject to noise pollution during takeoff and landing. The emissions created by burning jet fuel cause air pollution and, over decades, climate change: commercial aviation produces 4.9% of the total human contribution to global warming according to the IPCC. The International Air Transport Association (IATA) policy is to achieve carbon neutral growth in commercial aviation by 2020, and reduce carbon dioxide emissions by 50% by 2050. Reducing environmental impact is the crucial challenge in the design of future aircraft. In order for the Canadian aerospace industry, which generates $23.6 billion in revenue annually, to remain globally competitive, step changes in technology are required. One such technology is active flow control, which has been identified by the Advisory Council for Aeronautics Research in Europe (ACARE) as a key factor to produce the technologies required to meet the stringent environmental targets set on the aerospace industry.**The proposed research is aimed at the development and implementation of novel active flow control strategies with an emphasis on flow fields that are relevant to the Canadian aerospace industry. It will focus on boundary layer transition, as a precursor to controlling turbulent boundary layers, and shear layer separation. The importance of these flows is related to their impact on drag and noise production in a wide range of engineering systems. Notably, the skin friction drag due to a turbulent boundary layer is ten times larger than for the equivalent laminar boundary layer. In the case of separation, the resulting wake and periodic flow structures lead to undesired pressure drag and fluctuating aerodynamic loads. Both turbulent boundary layers and separated shear layers are responsible for increased noise emissions. Therefore, the delay of transition, control of turbulence and management of separated flows can lead to significant reduction in drag and noise emissions.**The methodology proposed is to leverage basic flow dynamics and instabilities to develop efficient closed-loop controllers. This aspect is closely linked with the development of sensors and actuators to enable the control systems. These control systems will be implemented and tested in an experimental framework. Therefore, the research is not limited to the study of the fluid flows and their control, but also addresses key practical challenges associated with the application of active flow control in real life. **The practical ramifications of this research are wide ranging. They include the reduction of drag, fuel consumption and noise emissions in a variety of commercially relevant fluid systems. These benefits will lead to a reduction in our dependence on fossil fuels and a decrease in greenhouse gas emissions. The proposed work is multidisciplinary, as it draws upon expertise in the areas of fluid dynamics, feedback control and dynamical systems. It is also transformative, since it addresses open questions that, in the long term, should lead to a paradigm shift not only with respect to engineering practices in the management of fluid flows related to energy-conversion devices and transportation, but also to the design practices for energy efficiency of these engineering systems.**The proposed research will involve 2 PhD, 3 MASc and 5 undergraduate students. These students will gain skills and expertise that are in high demand in many technological sectors in Canada, in particular the aerospace industry. Canadian companies such as Bombardier Aerospace and Pratt & Whitney Canada will benefit directly from both the proposed research and the highly qualified personnel that it will train.