Theoretical model and simulation of a twin-Screw multiphase pump with novel smooth screw rotors for gas-Oil mixed transportation

A pair of screw rotors, the core components of twin-screw multiphase pumps, primarily determine the pump performance. The conventional screw rotor contains unsmooth edges caused by unsmooth points in the cross-sectional profiles, which will lead to the abrasion, wear and fatigue near the unsmooth edges of the screw rotors during operation. For solving this problem, a novel pair of fully smooth screw rotors without unsmooth edges were proposed, and their cross-sectional profiles composed of the elliptical arcs and their conjugate curves were put forward. Parametric equations of the proposed screw rotor profiles were also derived, and then the effects of geometric parameters on the pump performance of the proposed screw rotors were discussed. Furthermore, the transient flow of the twin-screw multiphase pump with the proposed screw rotors were carried out by numerical simulations. The distributions of pressure and velocity in the proposed pump were obtained. The gap leakage and backflow velocity at each gap varying with time and location in the working process were also analyzed. The results indicate that the carryover of the proposed screw rotors is reduced by 90.49%, while its area utilization ratio is increased by 0.8%, and the length of the spatial contact curve is reduced by 25.71% in comparison with the conventional screw rotors. Thus, the superiority and feasibility of the proposed screw rotors are validated.