A composite fan stage representative of a modern UHBR architecture has been investigated experimentally on a novel test facility at Ecole Centrale de Lyon. The measurements show indications for a strong overloading of the tip region resulting in extensive blockage of the blade passage, which results in irregularities in the characteristic. Furthermore, a strong aerodynamic aperiodicity develops near the stability limit which is followed by Non-Synchronous-Vibrations.

These phenomena are analysed with extensive instrumentation providing highly resolved data on the local performance of the fan, including radial profiles upstream and downstream of the rotor. Unsteady pressure measurements helped to interpret the flow structure in the tip region. The results are presented across a range of operating points on the design speedline between peak efficiency and near stall.

In order to further analyse the observed phenomena, a numerical study has been conducted using the RANS solver elsA. The results of the steady calculations are in good agreement with the experimental results and will be discussed in detail. Indications for the onset of tip-leakage-vortex breakdown as well as a hub-corner separation with intense radial migration are observed in the simulations.

The obtained results are unusual for typical state-of-the-art transonic fans as they show the same experimental behaviour as high-pressure compressor front stages. Particularly the effect of blockage caused by tip leakage flow is atypical because of the comparatively small tip clearance. Hence, the results are of great interest for future designs of low speed fans.


Aerodynamic Investigation of a Composite Low-Speed Fan for UHBR Application

Division / Sponsor:
International Gas Turbine Institute (IGTI)

Paper Proceedings: https://asmedigitalcollection.asme.org/GT/GT2020/volume/84058

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