Electric Ducted Fan Aerodynamics and Optimisation

这项研究为未来的新型飞行器外形设计研究了全集成电子导管风扇推进系统的特性。这项研究的最终目标是开发一种性能指标和设计指南，考虑机身和推进系统之间相互依赖的空气动力学效应。将推进系统完全集成到机身中可以提供整体系统好处，因为可以省略推进安装部件，减少湿面积(摩擦阻力)和系统重量，同时允许更紧凑的机身设计以及紧凑的存储和运输可能性。然而，机身和推进系统之间的相互作用导致了气动复杂性的增加。与传统结构不同的是，机身产生的阻力是由推进系统通过吸入自由气流产生推力来克服的，所研究的结构将吸入造成飞行器部分阻力的流体。尽管增加了空气动力学的复杂性，但所谓的边界层摄取(BLI)可能会对飞行器的整体性能有利。对于轴对称物体，理论研究表明效率提高了20%左右。本文研究的概念是一个轴对称机身和一个完全集成的尾部直列附面层进气导流扇(EDF)。许多理论方法忽略或没有充分考虑飞行器与推进系统之间的相互依赖关系。当飞行器机身的边界层被吸入时，风扇将对上游的气流施加压力梯度，本质上影响身体周围的边界层。因此，通过BLI的阻力将因其周围气流的加速而改变。当使用人体边界层摄取时，推力和阻力的相互依赖使传统上在飞机性能量化中作为两个独立参数的推力和阻力的划分无效。因此，对边界层气动特性的详细研究是本研究的重要部分。计算流体动力学(CFD)可以模拟空气动力学行为，但其精度在很大程度上取决于流动的复杂性和计算资源。现有的计算方法不能充分验证机体和推进系统气动相互依赖的附加变量，因此本研究的目的是将实验和计算技术相结合。通过开发定制的低成本模块化实验风洞模型，可以生成高质量的实验数据，并用于CFD的验证。经过实验验证的CFD工具将增加对其使用的信心，使您能够进一步洞察实验测量技术范围之外的流动物理。实验和计算方法的结合使用将为开发合适的性能指标奠定基础，这些指标随后可用于后续的集成和优化。这项研究将包括：-低成本模块化实验风洞模型，用于对各种不同形状/配置进行实验研究-动力风洞测试-电推进和相关气动热效应的研究-实验和计算方法的高效和有效耦合-得出合适的性能指标和后续的性能优化-开发用于直列EDF飞行器集成的未来设计方法通过与QinetiQ的密切合作，研究受益。

This research investigates fully integrated electric ducted fan propulsion system characteristics for future novel air-vehicle configuration designs. The eventual aim of the research is to develop a performance metric and design guidelines considering the interdependent aerodynamic effects between body and propulsion system.The full integration of the propulsion system into an airframe can offer overall system benefits as propulsion mounting components can be omitted, reducing both wetted area (friction drag) and system weight while allowing for a more compact airframe design as well as compact storage and transportation possibilities. The interactions between airframe and propulsion system though result in an increased aerodynamic complexity. Unlike conventional configurations where the resulting drag of an airframe is overcome by a propulsion system producing thrust from ingesting free stream air, the investigated configuration will ingest the fluid responsible for part of the vehicle's drag. Despite the increased aerodynamic complexity, the so-called boundary layer ingestion (BLI) can potentially benefit the overall performance of the air-vehicle. For axisymmetric bodies, theoretical studies suggest efficiency improvements in the order of 20%. The concept investigated in this study has an axisymmetric body together with a fully integrated tail mounted in-line boundary layer ingesting Electric Ducted Fan (EDF).Many theoretical approaches though neglect or insufficiently integrate the interdependence between the air-vehicle and propulsion system. As the boundary layer of the vehicle's airframe is being ingested, the fan will impose a pressure gradient onto the flow upstream, essentially affecting the boundary layer around the body. Thus, the drag will be altered through BLI by the acceleration of its surrounding flow. The interdependence of thrust and drag when employing the ingestion of the body's boundary layer void the division of thrust and drag as two independent parameters as traditionally done in performance quantification of air-vehicles.Detailed investigation of the aerodynamic characterises of the boundary layer are therefore an essential part of this research. Computational Fluid Dynamics (CFD) can simulate aerodynamic behaviour, whereas the accuracy is greatly dependant on flow complexity as well as computational resources. The added variables of aerodynamic interdependence of the airframe and propulsion system are insufficiently validated by present computational methods.This research therefore aims to combine experimental with computational techniques. By developing a bespoke low-cost modular experimental wind tunnel model, high quality experimental data can be generated and used for validation of CFD. Experimentally validated CFD tools will increase confidence in their use, enabling further insight into the flow-physics beyond the scope of experimental measurement techniques. The combined use of experimental and computational approaches will underpin development of suitable performance metrics which can then be used for subsequent integration and optimisation. The aim is then to quantify the interdependence of the body and propulsion system, in order to define design guidelines for future applications having closely integrated propulsion systems with boundary layer ingestion.This research will incorporate:- Low-cost modular experimental wind tunnel model for experimentally investigating a variety of different shapes/configurations- Powered Wind Tunnel testing- Electric propulsion and investigation of associated aerothermal effects- Efficient and effective coupling of experimental and computational methods- Derivation of suitable performance metrics and subsequent performance optimization- Development of future design methodology for in-line EDF air-vehicle integrationThe research benefits through close collaboration with QinetiQ.