Numerical analysis for the effect of tip clearance in a low specific speed mixed-flow pump:

摘要

To study the influence of tip clearance on performance (external characteristics, pressure fluctuation and tip loss) of a low specific speed mixed-flow pump, unsteady simulation was performed for the whole flow passage with five tip clearance sizes (δ0?=?0?mm, δ1?=?0.10?mm, δ2?=?0.25?mm, δ3?=?0.75?mm and δ4?=?1?mm). The reliability of the numerical methodology was verified in external characteristics (efficiency, head and power) and fluctuation. The performance of the pump was obtained under different discharges and tip clearance sizes using ANSYS CFX. The results showed that the variation of tip clearance size has greater effect on the external characteristics under large discharges. Meanwhile, along the flow direction, the fluctuation coefficients near the impeller shroud increase gradually with the smaller tip clearance sizes (δ?=?0.10 and 0.25?mm), while for the larger tip clearance sizes (δ?=?0.75 and 1.00?mm), the significant increase of fluctuation near the shroud of impeller inlet is closely assoc...