Study of a screw rotor with different stocks and leads for a twin-screw multiphase pump

Abstract

Rotor profile generation and geometry characteristics play a dominant role in developing twin-screw multi-phase pumps. The aim of this work is to present mathematical procedures to calculate screw rotor profile generation, design rotor cutter tools, and rotor geometry characteristics with given stocks for twin-screw multi-phase pumps. Analyses of the profile generation of a screw rotor for a multi-phase pump are carried out. The resulting rotor profile with different stocks is developed on the basis of the calculation of the forming cutter tool profile. An iso-height contour plot is presented for describing the shape and size of the overlapped cavity of the rotors. By inspecting the iso-height contour plot, analysis of all the possible leakage flow through the inter-lobe clearance is performed. According to the iso-height contour plot, the blowhole provides the major leakage path for the basic chambers through the overlapped cavity. The minimum normal height of the overlapped cavity has a linear relationship with the stock. The larger stocks lead to greater leakage and reduce pump performance. The leakage flow through the overlapped cavity will be aggravated and the performance of the twin-screw multi-phase pump will decline with the increasing lead of the screw rotor.