Optimisation of Proprotors for Performance and Noise

随着全球对更可持续航空的推动，新的电动飞机平台正在开发中。这些可能是小型的电池驱动的无人机，也可能是大型的使用氢动力系统的商用飞机。人们还希望这种飞行器具有垂直起降能力，用作城际飞行出租车。这种动力系统通常由螺旋桨驱动，但缺乏设计和验证工具来优化这些新角色。此外，对于商用飞机来说，从涡轮螺旋桨飞机到氢动力系统的转变为航空声学研究提供了空间。在此之前，这种飞机上螺旋桨产生的噪音是次要的，因此不被视为主要设计参数。在人口密集的城市地区，随着重点转向可持续的“无声”飞行，噪音对公众的干扰正在成为一个重要因素。在螺旋桨噪声设计方面的研究有限，特别是在考虑垂直起降和向巡航飞行过渡时。本研究旨在占据这一空间，通过以下目标：设计、建造和调试一个螺旋桨试验台，并与公布的数据进行比较，开发一个螺旋桨性能和几何形状优化代码（Bath BEMT软件），通过将BEMT代码的预测与水平、垂直和过渡飞行的试验台测试相关联，来验证BEMT代码。并通过在钻机上使用麦克风阵列对螺旋桨进行声学测试来验证这些目标。这些目标将为下一代螺旋桨驱动飞机提供全面且经过验证的设计工具。给定任务参数和要求，如噪声、推力、扭矩和效率，将生成最优的螺旋桨。这样的螺旋桨可以应用到上述类型和应用的飞机上。这项研究将特别关注低雷诺数、大攻角、垂直起降-巡航过渡和失速后对螺旋桨设计的影响，因为这些在应用BEMT建模时仍然是最少验证的。为这些eVTOL应用生成优化螺旋桨的能力将允许这些新型航空航天平台的设计进步，同时最大限度地提高其推进效率，并最大限度地减少对公众的噪音干扰。高效、安静的螺旋桨在商用飞机上的成功应用，将通过替代推进系统提高可持续航空的可行性，加速从化石燃料动力飞行的过渡。

With the global drive towards more sustainable aviation, new electric aircraft platforms are being developed. These may be smaller scale battery-powered drone craft, or as large as commercial aircraft with hydrogen-electric powertrains. There is also the desire for such craft to have vertical take-off and landing capacities, for use as inter-city flying taxis. Such powertrains are most commonly driven by propellers, but there exists a lack of design and validation tools for optimising these for this new role. In addition, for commercial aircraft, the transition from turboprop to hydrogen-electric powertrains results in the scope for aeroacoustic research. Previously, the noise generated by a propeller on such an aircraft was secondary, and thus not considered as a primary design parameter. With the shift in focus towards sustainable, "silent" flight in dense urban areas, the noise disturbance to the public is becoming a significant factor. Limited research exists in the design of a propeller for noise, particularly when considering VTOL, and the transition to cruise flight. This research aims to occupy this space, through the following objectives: Design, build, and commission a propeller test rig and compare against published data Develop a propeller performance and geometry optimisation code (Bath BEMT software) Validate the BEMT code by correlating its predictions to rig tests in horizontal, vertical, and transitional flight Implement noise considerations into the design process, and validate these through acoustic testing of propellers on the rig with microphone arraysThese objectives will result in a comprehensive and validated design tool for the next generation of propeller-driven aircraft. Given mission parameters and requirements, such as for noise, thrust, torque, and efficiency, an optimal propeller will be generated. Such propellers could then be implemented onto aircraft of the types and applications listed above. This research will focus particularly on the low Reynolds number, high angle-of-attack, VTOL-cruise transition, and post-stall influences on propeller design, as these remain the least validated when applying BEMT modelling.The ability to generate optimised propellers for these eVTOL applications will permit the advancement of the design of these novel aerospace platforms, while maximising their propulsive efficiencies, and minimising the acoustic annoyance to the public. The successful implementation of high-efficiency, quiet propellers onto commercial aircraft will accelerate the transition away from fossil-fuel powered flight by increasing the feasibility of sustainable aviation through alternative propulsive systems.