This paper presents the performance analysis and a parametric study of equivalent ducted/un-ducted rotors using high-fidelity CFD methods. A model-scale ducted rotor case by NASA was analysed and used as the initial design. An equivalent un-ducted rotor producing the same thrust and power was first derived using the momentum theory. The ducted/un-ducted configurations were later scaled to support a four-rotor vehicle of 6,000 kg using a BEMT model. High-fidelity CFD simulations of the scaled designs were then performed. Far-filed acoustics of the two configurations was also examined using the FW-H equations. Compared to the equivalent open rotor, the ducted rotor had a significantly reduced frontal area and was also able to deliver the desired thrust at lower torque and reduced noise, but the power was higher due to the higher RPM. A parametric study was then performed in hover and in forward flight to study the performance trends subject to variations of tip speed, blade pitch, blade radius, chord, twist, and duct thickness. Kriging surrogate models were constructed to provide an impression of the performance response to the particular design change. Both configurations showed similar responses to most design variables, but the sensitivity was different between configurations and between flight conditions. Detailed analyses of the parametric results are presented to guide ducted rotor designs.

本文介绍了使用高保真 CFD 方法对等效管道/非管道转子的性能分析和参数研究。分析了 NASA 的模型比例管道转子外壳，并将其用作初始设计。产生相同推力和功率的等效无涵道转子首先是使用动量理论推导出来的。涵道/非涵道配置后来被缩放以支持使用 BEMT 模型的 6,000 公斤四转子车辆。然后对缩放设计进行高保真 CFD 模拟。还使用 FW-H 方程检查了两种配置的远场声学。与等效的开放式旋翼相比，涵道旋翼的正面面积显着减小，并且还能够以更低的扭矩和更低的噪音提供所需的推力，但由于更高的 RPM，功率更高。然后在悬停和前飞中进行参数研究，以研究受叶尖速度、叶片间距、叶片半径、弦、扭曲和管道厚度变化影响的性能趋势。构建克里金代理模型以提供对特定设计更改的性能响应的印象。两种配置对大多数设计变量都表现出相似的响应，但不同配置和飞行条件之间的灵敏度不同。对参数结果进行了详细分析，以指导管道转子设计。构建克里金代理模型以提供对特定设计更改的性能响应的印象。两种配置对大多数设计变量都表现出相似的响应，但不同配置和飞行条件之间的灵敏度不同。对参数结果进行了详细分析，以指导管道转子设计。构建克里金代理模型以提供对特定设计更改的性能响应的印象。两种配置对大多数设计变量都表现出相似的响应，但不同配置和飞行条件之间的灵敏度不同。对参数结果进行了详细分析，以指导管道转子设计。