Abstract:Full cross-flow pump is a new type of pump with its motor integrated. However, during its operation, the occurrence of clearance backflow between the stator and rotor can disrupt the flow field distribution inside the impeller, leading to energy loss, pressure fluctuations and noise in the pump unit, even affecting the normal operation of the pump station. To understand the influence mechanism of clearance flow on the pump unit, firstly, the hydraulic characteristics of the clearance flow between the stator and rotor of a full cross-flow pump unit was investigated through the methods of numerical simulation and model experiments. Secondly, combined with scheme design method of Doehlert Matrix-response surface optimization, the inlet and outlet clearance structure of the stator and rotor was optimized, with the overall operating efficiency of the unit, the axial velocity uniformity and the average vortex angle at the outlet section of the outlet channel selected as the evaluation indexes. Lastly, the influence mechanism of the inlet and outlet clearance structure of the stator and rotor on the performance of the pump unit was revealed, along with the final optimized scheme for the inlet and outlet clearance between the stator and rotor obtained, that was the outer extension section t1 was 4.921r, the outer contraction section x1 was 0.624r, the inner extension section t2 was 3.655r and the inner contraction section x2 was 1.6r where r represented the width of the clearance between stator and rotor in which case, the head and the operating efficiency of full cross-flow pump can be improved by around 10.3% and 5.2%, respectively.