Analysis of flow characteristics and pressure pulsation in impeller region of shaft tubular pump device with different tip clearances

The shaft tubular pump device (STPD) impeller flow characteristics and occurrence regularity of tip clearance leakage (TCL) flow were investigated using a steady and unsteady three-dimensional numerical simulation with computational fluid dynamics as the basis. The energy performance, internal flow characteristics, and pressure pulsation characteristics of the STPD under various tip clearance widths were examined. The results indicate that the performance of STPD is negatively impacted by an increase in tip clearance width. With an increase in tip clearance width from 0.2 to 0.5 and 1.0 mm, the efficiency of the STPD decreases by 1.57% and 3.13%, respectively, when flow coefficient is 0.49. Tip clearance width variation has less of an impact on the impeller inlet’s flow, especially the velocity distribution. When tip clearance width grows, the flow pressure pulses from impeller flange to hub side. Meantime, the unstable region at the impeller shifts from the rim to the hub, and TCL flow develops outward to the nearby blades. As flow rate increases, tip clearance width has a gradually decreasing effect on flow.