Effects of tip radial distortion on an axial fan with foam metal casing treatment

The significant impact of inlet distortion on fan/compressor performance and stability makes it a critical issue that must be addressed in the design and optimization of aeroengines. This study investigates the effects of tip radial distortion (TRD) on an axial flow fan with foam metal casing treatment (FMCT) through experiments and numerical simulations. It is found that TRD leads to a redistribution of the inlet flow and velocity near the blade tip, which results in a higher blade loading compared with that in UNI. The forward spillage prematurely of Tip Leakage Vortex (TLV) caused by TRD is the main reason accounting for a decreased SM of the fan in the present research. The mismatch as well as the strengthened TLV are the two key issues for the deteriorated performance. Due to TRD, the SM of the fan is decreased by 10.7 %. And the stall margin improvement (SMI) generated by FMCT is 20.9 %. Efficiency loss caused by FMCT is 0.3 %. Radial distribution of flow parameters at the inlet of rotor is slightly altered by FMCT. FMCT mainly affects the flow structure near the blade tip. FMCT releases the tip blade loading by supplying an additional channel for flows near the casing.