Coupled Design of Multi-Component Distortion-Generating Devices for Aircraft Engine Ground Tests – Part II: Experimental Characterization in a Closed-Loop, High Speed Test Rig

Next generation aircraft engine configurations, featuring a higher level of engine-airframe integration, are subjected to increased flow distortion levels at the fan inlet. The presence of such non-uniformities should be considered as early as possible in the design cycle, as it can have an impact on the engine performance, operability and vibration. Since testing under realistic distorted inlet flow is crucial in order to evaluate such effects, there is a clear need for devices able to generate complex distortion patterns. Part I of this two-part paper presents a numerical methodology enabling to design distortion generating devices capable of reproducing complex steady combined total pressure and swirl angle distortion patterns. The methodology has been applied to generate four different sets of distortion screens: one honeycomb total pressure screen, one swirl vane assembly, and two devices consisting of a coupling of the two components. The second part of the paper focuses on the experimental characterization of the distortion screens in the VKI R4 high speed test rig. The closed-loop facility has undergone major design modifications in order to implement the new distortion devices test section and reproduce engine-like flow conditions. The measurements have been carried out by means of stereo-PIV and multi-hole aerodynamic pressure probes. The cross-comparison between the two techniques allows to discuss the limitations of each technique. Finally, the comparison between the experimental results and the simulated patterns is presented and discussed.