[Julian121]

I have asked a similar question before, but I have not found any solution yet.

I am analysing the FFT of absolute pressure signal of the numerical probe for several operating points from choking to stalling.

In the current operating point which is close to stalling according to experimental data, the FFT shows that there exists a peak at 806.344727 Hz (0.42 BPF) while the BPF is 1900 Hz.

According to literature, a stall cell which is a region with low axial velocity and high tangential velocity rotates with 20%-70% of rotational frequency of rotor.

In my problem, rotor has 50 Hz rotational frequency which shows that 806 Hz is not a stall cell frequency.

Still, I cannot explain this contradiction and the source of the 806 Hz frequency.

Could someone please help me?

IGV/Rotor/Stator have 34/38/37 blades.