Effect of Axial Spacing on Compressor Stability

Experimental studies are carried out at a low speed axial compressor with five different rotor/stator gaps. Analysis of the effect of axial spacing of two successive blade rows on the measured mean flow coefficient at stall inception and on the flow range of compressor under multi-cell rotating stall operating conditions proves that the stator can suppress the flow disturbance in the compressor and strengthen the stability of the compressor. Experimental data show that the stall flow coefficient decreases by reducing the axial spacing of successive blade rows. Moreover, by reducing the axial spacing, the stall pattern transition pace from multi-cell stall to single-cell stall can be shifted. And the compressor directly slips into single-cell stall at 21.0% C(subscript R) axial spacing. By analyzing the pressure fluctuation closed to the surge line, it can be known that there exists an eigenfrequency where the amplitude of the oscillating pressure suddenly and dramatically increases as the compressor runs close to the surge line and this pressure disturbance is relevant to the compressor instability.