Study Of The Internal Flow Field And Characteristic Of The Screw Centrifugal Pump

With the development of technology and economy, hydraulic machinery is widely used to transport all kinds of solid matter in many fields. As a new kind of impurity pump, screw centrifugal pump combines the advantages of screw pump and centrifugal pump, and the special structure can make use of their advantages sufficiently. Compared with the traditional impurity pump, screw centrifugal pump has a series of strong points, such as: good through-flow condition, not easily blocking, little abrasion in overflowing parts, high efficiency, longevity of service, low cost and good accommodation.As a result of system changes and other reasons, pumps often run at off-design conditions, mainly in the small volume. There will be the phenomenon of the back flow at the impeller inlet and the outlet. Besides that, there also come forth small vortex and changes of the corresponding pressure field and velocity field. So, the back flow not only impact the efficiency, stability and noise of the pump, but also impact the cavitations of the pump obviously. Therefore, it has important practical significance to reach on the back flow which occurred when the centrifugal pump run in the small volume and the controlling of the back flow. In this paper, the 100LN-7 type of screw centrifugal pump as a example to design, and turbulent Reynolds equations, standard k-e turbulent model and sliding mesh are used, Using the FLUENT software, numerical calculation accounted flow status of the interior flow passages based on rinsing medium, the results indicated using the model can really reflect the back flow phenomenon that obviously existed in the flow field of the pump, and found two methods can control the back flow effectively, namely added the annular wall on the entrance of the volute casing and added the wall on the impeller's lamina, the ratio of the wall's altitude and the volute casing's breadth adopted h/B=0.333 equally, at the same time validated the feasibility of the two back flow control methods of the screw centrifugal pump. The numerical simulation shows that two kinds of the new methods to control the back flow for the single blade screw centrifugal pump back can improve the performance of screw centrifugal pump effectively.The 100LN-7 type of screw centrifugal pump with double blades is designed and calculated in 3D steady flow under multiple loading conditions to study the influence of double blades to the pump external characteristic. Through the simulation the 100LN-7 type of screw centrifugal pump with double blades in 3D unsteady flow, unveiled the disturbance between the static and dynamic flow of the impeller and the volute generates the unsteady influence in screw centrifugal pump. And the pressure oscillation is obtained on the screw centrifugal pump flow channel exports. At the same time, it is discovered that the fluctuation range of outlet pressure is large. Using the results of the simulating the flow of the screw centrifugal pump with double blades transport the two phase currents, the different solid phase density, different pellet particle size operating mode internal pressure are studied. The results of research can offer some information to the screw centrifugal pump's design and the performance improvement.