Design And Optimization Of Non Contact String Rotor Pump

Compared with ordinary straight spur gears,the cosine curve gears,due to different tooth shapes,not only have small sliding coefficient,but also have greater surface contact strength and bending resistance.In addition,tests have shown that its average flow rate is larger than that of a straight spur gear pump of the same size,while its flow pulsation smaller.Therefore,it has a broad development prospect in industrial applications.However,the tooth profile's dissatisfying the conjugate condition gives rise to slight interference of the two cosine rotor tooth profiles if the circumflexion is installed at the position where the indexing circle is tangent.Therefore,the cosine rotor can only be meshed with the conjugated non-cosine rotor.Although this meshing method has smaller sliding coefficient,contact stress,and bending stress compared with involute gear meshing,complexity of conjugate tooth profile curve has greatly increased the cost of rotor machining,thus limiting its promotion and application.Based on the above issues,a non-contact cord-rotor pump was designed in this paper,and the pump was analyzed in the following four aspects:1)Deduce the parameter equation of the cosine rotor profile,and then the profile equation of the profile of the other rotor meshing with the cosine rotor is solved with the gear meshing principle.Analyze the condition of the two rotors' non-interference in theory with the solved two-rotor profile equation.The smaller the value of h/r,the smaller the interference between the two rotors.When h/r=0,the two rotors do not interfere.By using the two-rotor parameter equation and the 3D modeling software UG,the 3D meshing diagram of the two rotors is built to simulate the motion of the rotors.The motion gap of the two rotors is measured,and the minimum gap(?)between the two rotors is obtained,which is 0.1mm.2)Explore the flow characteristics of cord-rotor pump,and then the area-scan method is used to gain the instantaneous flow of the non-contact cord-rotor pump considering the rotor gap and neglecting the rotor gap,respectively.According to the analysis of the flow.the instantaneous flow pulsation decreases with the increase of rotor teeth.Approximate value and ideal value solution methods are used to gain the approximate and ideal values of cord-rotor pump displacement.The operating efficiency of the cord-rotor pump is gained and analyzed using the rotor pump empirical leakage formula,showing the efficiency of the cord-rotor pump decreases as the gap between the rotors or the inlet and outlet working pressure difference increase.3)The cosine rotor is optimized to find out the smallest rotor volume per unit displacement.The parameters and constraints to be optimized are set according to the smallest rotor volume per unit displacement,and then M file is written and the rotor of the cord-rotor pump is optimized by calling the optimization functions in the MATLAB software.Calculate the rotor volume per unit displacement with the cosine rotor parameters before and after optimization,and then a 7.46% reduction in rotor volume is seen after optimization by comparing the two results.4)Conduct simulation analysis on the flow conditions inside the non-contact cord-rotor pump.And then the cord-rotor pump model is imported into the gambit software to divide the grid to meet the calculation requirements,and then set the corresponding wall conditions.The fluent software is also used to simulate and analyze the internal flow of the cord-rotor pump.Through simulation,it is found that the working efficiency of the pump decreases with the increase of the gap between rotors or working pressure difference,and is verified by theoretical derivation.The maximum working pressure difference between the inlet and outlet decreases with the increase of the gap with the same rotation speed.