Effect of blade-row axial spacing on the stage performance of an axial supersonic through-flow fan

Rotor-stator interaction has a large impact on the performance of axial compressors. Previous studies have suggested that less blade-row axial spacing (δz) of an axial flow compressor is associated with improved efficiency. However, these studies primarily focused on the subsonic-axial turbomachinery. The impact of δz on the performance in an axial supersonic through-flow fan (STFF) stage remains unclear. This study explores the effect of axial spacing on the performance of an STFF stage using unsteady numerical simulations. The results show that both the total pressure ratio and isentropic efficiency are reduced when axial spacing changes from δz=1.0, whether it increases or decreases. The maximum drop in total pressure ratio and efficiency reaches 2.0% and 1.0% when δz=4.0 and δz=2.0, respectively. Furthermore, the loss production mechanism causing the variation in stage performance is revealed. When axial spacing drops from 1.0 to 0.5, the stage loss dominated by the wake-shock interaction loss is enhanced due to the stronger wake strength. When axial spacing rises from 1.0 to 2.0, however, the wake mixing loss plays a leading role in stage loss. And it is enlarged with the increase of axial spacing because of a larger viscous dissipation.