Numerical investigation on screw rotor deformation and influence on volumetric efficiency of the twin-screw multiphase pump

The thermal and force deformation model was established to investigate the rotor deformation and its effect on the volumetric efficiency of the twin-screw multiphase pump with high gas volume fractions (GVFs). Based on the ANSYS software, the deformations under different GVFs were calculated. The influence of the deformations on the clearance, the leakage flow rate and the volumetric efficiency was then analyzed. It was found that the largest clearance variation under the deformation was the radial clearance, followed by the circumferential clearance, and there was little change in the flank clearances. With the GVF increasing from 80% to 94%, the pump volumetric efficiency increased gradually. However, it decreased sharply when the GVF exceeded 94%. Finally, the rotor clearances were analyzed and optimized, and the recommended mounting clearances were proposed, which could decrease the leakage and prevent the rotor from being stuck when large deformations occurred.