Research On The Construction And Performance Of A Multi-point Meshing Screw Rotor For The Twin-screw Pump

A pair of intermeshing screw rotors has a great influence on the working performance of the twin screw pump.The circumferential meshing gap and radial meshing gap formed by the traditional twin-screw rotor in the meshing process have a large internal leakage during operation,which reduces the volumetric efficiency of the twin-screw pump.In order to improve the gap structure of the twin-screw rotor and improve its sealing performance,based on the tooth profile meshing principle,in this dissertation the author studies the design method of the cross-section profile of the twin-screw rotor at any transmission ratio,and establishes meshing models between points and cycloids,arc and cycloid equidistant curves,involutes,and ellipses under arbitrary transmission ratio.The meshing model of the conjugate line of the arc is obtained;and the elliptical arc;and then a multi-point meshing screw rotor of the twin screw pump is proposed,which is constructed by the conjugate line of the elliptical arc and the elliptical arc.The geometric characteristics of the multi-point meshing screw rotor proposed in the study,and its plane meshing characteristics and spatial meshing characteristics are analyzed.The formation mechanism of the meshing gap in the different directions of the twin screw pump is analyzed,and a mathematical model is established.The leakage characteristics of the meshing gap in different directions are studied,and the working process of the multi-point meshing screw rotor is numerically simulated.The pressure distributions and velocity vector fields at the spiral working cavity,the screw rotor tooth surface and the screw meshing gap are obtained.The results show that the proposed multi-point meshing screw rotor changes the geometric structure of the rotor meshing gap.The multi-point meshing screw rotor and the inner wall of the pump cavity form a labyrinth seal through multi-point meshing at the circumferential gap.The main screw rotor and the inner wall of the pump cavity form a labyrinth seal.From the twists and turns of the flow path of the screw rotor at the radial meshing gap,the wear adaptability is improved at the normal gap,the sealing performance of the twin screw rotor has been significantly improved.The internal leakage of the twin screw pump is effectively reduced,and the volumetric efficiency of the pump is improved.The transient numerical simulation of the flow fields shows that the pressure in the spiral working cavity of the proposed multi-point meshing screw rotor is obviously stepped along the axial direction.The pressure of the tooth surface of the master and slave screw rotors is clearly separated along the space contact line,and the space is sealed.The internal leakage at the meshing gap of the twin-screw rotor is significantly reduced.The research contents of this paper expand the types of twin-screw rotors and changes the geometric structure of the rotor meshing gap,which is of great significance for improving the sealing performance of the twin-screw rotors.