| Elliptical rotor scraper pump overcomes the shortcomings of traditional positive displacement pump such as loose structure,complex manufacturing process and difficult assembly and maintenance.Its novel structure lies in the realization of liquid booster output through the rotation of elliptical rotor and the corresponding swing of scraper.In the movement of scraper pump,the relationship between the scraper’s self-locking and fluid dynamics determines whether it can work normally and its performance.In this paper,the structure principle of elliptic rotor scraper pump is described,the basic mathematical model is established and the self-locking characteristics are analyzed.The structure and working principle of the pump are discussed and compared with several typical pumps which have been put into commercial use.On this basis,the threedimensional model of the elliptical rotor scraper pump is established,and the mathematical model between the elliptical rotor and the swinging scraper in the pump is given.Through force analysis,the self-locking characteristics of elliptical rotor scraper pump are further studied.The kinematics analysis of elliptical rotor scraper pump is completed.The kinematic analysis is divided into two aspects: steady state analysis and follow-up analysis.The kinematic rationality of elliptic rotor scraper pump is verified by the output curve of rotation Angle and contact force in steady state analysis.The maximum rotor speed that the swing scraper can follow stably is obtained from the following analysis,which is of great significance to the subsequent engineering practice.The dynamic motion trajectories and equations of elliptical rotor and oscillating scraper are studied by three methods and the transient dynamics analysis is carried out.Based on the general form of elliptic curve equation,the profile equation of elliptic rotor is reestablished,and the dynamic motion problem is transformed into the clearance control problem between elliptic rotor and swinging scraper.Then,ergodic search method,sequential quadratic programming algorithm and pseudo-Newton-penalty function method are introduced or proposed to realize clearance control.By applying constraints,numerical simulation,polynomial fitting and other processes,it is verified that the three methods can effectively control the clearance between elliptical rotor and swing scraper.Considering the control effect,calculation time and robustness of the three methods,the quasi-Newton-penalty function method is selected as the research method to solve the trajectory and equation of dynamic motion,and the Angle equation and angular velocity equation between the elliptical rotor and the swinging scraper are obtained.According to the results of kinematic analysis,transient dynamics analysis is carried out,and it is found that the maximum equivalent stress and maximum deformation appear on the swing scraper.It solves the mathematical problem of flow field analysis of complex structure like scraper pump and provides the theoretical basis for the subsequent flow field analysis.The flow field of elliptical rotor scraper pump is analyzed in Fluent software.Based on the dynamic motion trajectories and equations mentioned above,the moving area grid is divided by using the three-dimensional unstructured hexahedral dynamic grid method,and the rationality of the grid is analyzed.The working process of elliptical rotor scraper pump is simulated numerically by using the knowledge of computational fluid dynamics,and the distribution of internal pressure field and velocity vector of elliptical rotor scraper pump at different rotor speeds is obtained.The relationship between rotor speed and maximum pressure,rotor speed and flow rate is summarized.Finally,the prototype of elliptical rotor scraper pump is manufactured and tested,and the flow field simulation data is compared with the test data.The prototype test proves that the elliptical rotor scraper pump is feasible on the structure principle,indicating that the pump has advantages in improving the fluid pressure and velocity. |
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