Study On Parametric Geometry Modeling Method Of The Bulb Section Of Postpositional Bulb Tubular Pumping System

The pumping stations in the South-North Water Diversion Project have the characteristics of low-lift, large flow capacity and year-long run-time. For their economic characteristics, the tubular pump is especially suitable for the South-North Water Diversion Project, in the low-lift case, which has less hydraulic loss, large discharge capacity, high system efficiency and the lift head lower, the more obvious superiority. Consequently, it has good application value and developing potential.Study shows that, when the postpositional bulb tubular pump run in the efficient area, the hydraulic loss of bulb section is the largest share of the whole pump device(in addition to the impeller). It can be seen that the structure of bulb section have a greater impact on device efficiency. To achieve the optimal design about the structural shape of the bulb section, it necessary to first solve the parametric design problem of the geometry of the bulb section. This paper analyzes the structure of bulb section profoundly, which include the guide vane section that closely linked to the bulb, the size of pump barrel and bulb, the tail′s shape of pump barrel and bulb, and the cross-section shape of the upper and lower body support and affect the device efficiency. Taking reducing the hydraulic loss of bulb section as the aim, this article studies how the structure of bulb section affects the fluid drag coefficient and comparatively analyzes the existing domestic and foreign outstanding tubular pump devices to get the numerical methods of each geometric or structural parameters of bulb section, lastly determine the key design parameters including the spreading angle of guide vane hub,the equivalent spreading angle of guide vane section, the pump barrel diameter, the bulb diameter and so on.Pro/ENGINEER is the automation software product about mechanical design of Parametric Technology Corporation USA, which was the first system with parametric function. In this paper, it is used to create a solid model for bulb section of postpositional bulb tubular pumping system. Using the procedural tool-program to finish some works that contain setting up independent parameters, adding relationship, controlling appearance of the features and editing procedures. Designers can input parameter value through the man-machine interface or data files to modify and create model quickly. Use the function of Family Table to create a library of bulb section including different sizes and characteristics.Finally, this paper estimates the hydraulic loss and analyzes mutative trend about the flow basal area for the bulb section that finishes parametric modeling design. The results show that only a few different independent parameters, the hydraulic loss of bulb section is small and the mutative trend about the flow basal area tends to slow, so water flow should be better. For the optimal design about the structural shape of the bulb section, the result represents a crucial step.