Damage effects on the windmilling aerodynamics of low pressure ratio fans

在发动机运行期间，如果发动机关闭，发动机将进入风车状态，风扇将由于滑枕压力而继续旋转，但不会产生功。在未来低压比涡扇设计的发展中，表征发动机风扇在风车上的阻力和转速是至关重要的。本项目旨在解决这一问题，通过采用数值和实验相结合的方法来研究风车的气动流场。由于这种情况通常会在发动机损坏后发生，因此在调查过程中也会考虑叶片损坏。惠特尔实验室的单流垂直低速试验台将进行改装，以代表未来的涡扇发动机设计。这些修改将包括重新设计轮毂和机壳管路，以及转子和定子叶片。在该项目的后期阶段，叶片将被进一步改装，以包括典型的在役损坏模式。然后将在该试验台上进行测量，以研究风车内的风扇流场。实验研究将与有无叶片损坏的风扇设计的数值模拟相补充。该项目的主要预期成果是对未来低风扇压比发动机的设计建议，以及开发一种低阶建模工具，该工具可用于工业上预测不同叶片损伤程度下风车中风扇的阻力和转速。

During engine operation, if there is an engine shut-down, the engine will enter a windmilling state, where the fan will continue to spin due to the ram pressure but no work will be generated. It is critical in the development of future low pressure ratio turbofan designs to characterise the drag and rotational speed of the engine fan at windmill. This project aims to address this, by using both numerical and experimental methods to investigate the aerodynamic flow field at windmill. As this condition will often occur following damage to the engine, blade damage will also be considered during the investigation. A single stream vertical low speed rig in the Whittle Laboratory will be modified to be representative of a future turbofan engine design. These modifications will include the redesign of hub and casing lines, as well as the rotor and stator blades. The blades will be further modified in the later stages of the project to include typical in-service damage patterns. Measurements will then be taken in this rig to investigate the fan flow field at windmill. The experimental study will be complemented with numerical simulations of the fan design with and without blade damage. The main expected outcomes from this project are design recommendations for future low fan pressure ratio engines, as well as the development of a low order modelling tool that can be used in industry to predict drag and rotational speed of the fan in windmill for different blade damage levels.