High blade lift generation through short rotor–stator axial spacing in a tiny pump

Short rotor–stator axial spacing has been demonstrated to be beneficial to the aerodynamic performance of subsonic compressors. In this paper, it is further verified that this benefit partly originates from the improvement of the rotor blade lift. A tiny axial pump is investigated both numerically and experimentally with three different rotor–stator axial spacings. The time-accurate simulation indicates that both the peak and average rotor blade lifts are enhanced as the axial spacing decreases. The potential field of the downstream stator has significant effects on the pressure distribution in the rotor when the blade rows get close. The two-dimensional (2D) PIV measurement demonstrated that short axial spacing generates high circulation around the rotor blade due to the flow tube compression, which contributes to the blade lift improvement. Besides, close blade-rows axial spacing generates enhanced unsteadiness for the inlet flows of the downstream stator, which should be taken into consideration in the design process.