On the basis of the geometric characteristics of the rotor and the cylinder of a synchronal multiphase pump(SRMP)

the mathematic models of the relative motion between the rotor and the cylinder were established. The relative locus curves and velocities of the various points on the cylinder end face were calculated and analyzed. The frictional loss on the end faces was discussed when the clearance between the rotor and the cylinder end faces was assumed to be a constant value. The result shows that the average relative velocity between the cylinder end face and the area which is opposite to the vane slot on the rotor end face is much greater

and the frictional loss therein is considerable. When the clearance between the rotor and the cylinder end faces is viewed as a constant value

the average frictional loss on the end faces in the SRMP prototype is only 1.4 W and decreases by 98.2% compared with that in the rotary pump with a fixed cylinder. Due to the small relative velocity between the rotor and the cylinder end faces

a contact seal may be used to reduce the wear on the end faces and the leakage loss through the clearance.