Non-Intrusive flow distortion measurements within a turbofan intake
Short and slim aero-engine intake designs for very high bypass ratio configurations cause notable levels of unsteady distortions at the fan face especially under cross-wind or angle of attack operation during aircraft take-off. Such distortions can adversely affect the engine’s performance, operability, structural integrity and safety margin with potentially catastrophic consequences for the entire propulsion system. 
Current practices for aero-engine testing and certification rely on a low number of intrusive pressure measurements at the fan face to characterise the distortion levels. Given the known limitations of currently used methods (low spatial resolution, intrusive nature) the existing technologies are inadequate to reduce the risk on the development and certification of future novel systems.   
NIFTI aims to address this gap by demonstrating a non-intrusive technique to measure velocity fields across a plane located upstream of a large diameter fan of a high bypass ratio aero-engine which has never been achieved. This method will provide synchronous datasets across the measurement plane with at least one order of magnitude higher spatial resolution than current methods. The implementation will demonstrate a highly automated and flexible multi-camera system within a representative industrial test environment. A number of more advanced, non-intrusive measuring technologies will be assessed such as 3D PTV or Helium Filled Soap Bubbles (HFSB) to further enhance the outputs of the selected baseline solution. 
The experimental activities will be supported by numerical campaigns and advanced data processing and flow analysis methods that will be used to analyse the highly unsteady nature of the flow distortions that will be measured during NIFTI’s experimental campaigns. These outcomes will ultimately unlock the complex aerodynamics of closely coupled fan-intake systems and aid the development of novel design rules for future, stall-tolerant aero-engines.