Damage effects on the windmilling aerodynamics of low pressure ratio fans

在发动机运行期间，如果存在发动机停机，则发动机将进入风车状态，其中风扇将由于冲压压力而继续旋转，但不会产生功。在未来的低压比涡扇发动机设计中，确定发动机风扇在风车上的阻力和转速是至关重要的。本计画针对此问题，以数值与实验相结合的方法，研究风车的空气动力流场。由于这种情况通常发生在发动机损坏之后，因此在调查期间也将考虑叶片损坏。将对惠特尔实验室的一台单流垂直低速试验台进行改进，使之成为未来涡轮风扇发动机设计的代表。这些修改将包括重新设计轮毂和外壳线，以及转子和定子叶片。叶片将在项目后期进一步修改，以包括典型的使用中损坏模式。然后在此装置上进行测量，以研究风车上的风扇流场。实验研究将与有和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为未来的低风扇压比发动机提供设计建议，以及开发一种低阶建模工具，该工具可用于工业中，以预测不同叶片损伤水平下风车风扇的阻力和转速。

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.