In the design of submersible pumps, the flow director determines the structure and performance of the pump to some extent. High-efficiency submersible pumps require not only efficient impellers, but also flow directors that are well matched to the impeller.
If the deflectors do not match, not only reduce the pump efficiency, but also affect the stability of the pump to a certain extent 111. In the past, the design of the deflector was based on the traditional method of drawing drawings, and then make a model, and then on the test bench Test its performance until a satisfactory result is achieved. Obviously, this approach knows little about the flow inside the deflector, and it takes a long time to develop and costs a lot. With the development of computer technology, researchers have studied the internal flow of submersible pumps through numerical simulation methods. With CID (Canpumiaial FUidDynanCS) numerical simulation technology, you can shorten product development time, reduce costs, and can better grasp the internal flow laws. In the process of using Computational Fluid Dynamics (CF) simulation, the establishment of a solid model is the premise of the CFD calculation. At home and abroad, researchers have focused on the three-dimensional design of submersible pumps mainly on the three-dimensional modeling of the impeller, while the research on the deflector is less. 121. The deflector is a complex spatial curved body in the design process, the blade Due to the complex shape, serious distortion and inconsistent thickness, the modeling of the deflector blade becomes the key and difficult point for the establishment of the entire solid model. The author uses the 250Q125 submersible pump as an example, using AuAD2006 software to introduce three-dimensional modeling methods and steps of the submersible pump diverter based on the trim chart.
1 Data preparation According to the submersible pump design parameters (such as flow, head, speed and efficiency, etc.) for hydraulic calculations, the main structural parameters of the pump are obtained. The velocity coefficient method was used to calculate the geometric dimensions, angles, and number of blades required for the drafting of the deflector blades, and a hydraulic model of the deflector blades was generated. For the 250Q25 submersible pump, the design parameters are as follows: Efficiency/%76 The calculated parameters of the deflector are shown in Table 1, and the axial projection diagram is shown.
Table 1 Structure parameters of the deflector Tb 80553109.9273090857 The deflector blade is painted with a twisted triangle method. The steps are as follows: 1) Make a wooden mold section on the axial projection diagram; 3) Draw a streamline on the development diagram; Fund project: Shanxi Agricultural University Science and Technology Innovation Fund Project (2 (1) 8034) -) Male, Taigu, Shanxi, lecturer, (E blade thickened; leaf painting quality inspection; inspection of the inlet flow area between the leaves.
The deflector blade and streamline development diagrams of the deflector blades are shown as and.
2 Methods and procedures for submersible pump deflector modeling Three-dimensional modeling of the submersible pump deflector based on the cut chart is to use the section data on the deflector blade trimming chart, in combination with the axial projection diagram, to inversely calculate the shaft of the working face of the blade. Face line coordinates. Based on the coordinate values ​​of the three-dimensional control points of the flow line of the shaft section, curve fitting is performed, and the process of modeling the blade surface is then performed to generate the blade body.
21. Generation of control points for blade working face According to the blade woodcutting diagram, the plane coordinates of the axial projection of the blade and the horizontal coordinate of the blade are transformed into space, so that the three-dimensional coordinates of the point on the sectional line in each section can be obtained. The control point of the blade face. The coordinate data of the control point of the blade working face is shown in Table 2.
Table 2 Drifter Blade Woodcutting Chart Workface Coordinates Flow Line Coordinates within Stream Coordinates a—a Inlet Edge Outlet Edge 22 Generation of Blade Axial Section Lines There are several ways to generate a three-dimensional curve. The curve equation can also be imported into the AuoCAD 2D curve. This article uses the method of inputting control point data.
First of all, according to the control point data of the working face obtained in Table 2, the generated point data is converted into the xl file format supported by AutoCAD. That is, the XYz XYZ inducer inner and outer streamlines are developed 36.632, and the object can be closed by rotating around the axis 360 ° to create wheel real 649.5 24 body. The deflector hub entity is as shown. The specific operation is to call the following 963.3 16 pull-menu: drawing - polyline; drawing - area; drawing - modeling - Then, according to the three-dimensional coordinates of the flow line inside and outside the blade, draw the control point of the working face of the blade, and sequentially connect the corresponding section on the inside and outside The two control points of the streamline generate the axial section of the blade working plane, as shown. The specific operation is to call the drop-down menu: plot-point-multipoint; plot-line.
Blade face Axis section line Fig4 The 23rd generation of blade face and blade solids First, a 3D surface is created by lofting a set of curves containing two or more cross-sectional curves. The curve on the cross section generates a smooth blade face through a smooth fit as shown. The specific operation is to call the drop-down menu: Drawing - Modeling - Lofting.
Second, according to the processing requirements of blade thickness, that is, from the work surface to the back thickening, the outer flow line is equal thickness 4mm inner flow line is equal to the thickness of 3mm to thicken the blade working surface to generate the blade solid model, as shown. The specific operation is to call the drop-down menu: modify - three-dimensional operation - thickening.
24 Modeling the deflector The deflector is a combination of the blade body and the hub entity. The deflector hub is an axisymmetric body of revolution and, from the point of view of feature formation, belongs to the feature of rotation in the bulge feature. The rotation feature is a type of feature that results from the rotation of a feature profile around a rotation centerline over a certain angle. Relatively speaking, this type of feature is relatively simple, and the control parameters are also limited. It is relatively easy to integrate the blade entity and the diffuser hub entity. In a three-dimensional space, a three-dimensional annular array operation is performed on the blade around the hub rotation axis to obtain the deflector entity. , as shown. The specific operation is to call the drop-down menu, modify the "three-dimensional operation - three-dimensional array.
Fig. 3 Modeling issues to be aware of in order to ensure the validity of the data in the section transformation process. To increase the number of section control points 151, especially in curvature comparison. Great location.
2) When a section of a wood mold is to be made on the axial projection diagram, the sections are generally taken at equal distances, and the distance between the severely curved parts should be appropriately reduced.
3) After the model is built, call the EXPCRT command to output the drawing result as an ASC file (extension a) for subsequent processing in GAMBT, which will then lay a solid foundation for CF analysis.
4 Conclusions The three-dimensional modeling of the deflector based on the cropping diagram can systematically reflect the design theory of the inducer blade, so as to better conduct in-depth research.
The three-dimensional modeling of the submersible pump deflector is the basis and prerequisite for the analysis of its internal flow field. Based on the three-dimensional modeling function of AuAD, the three-dimensional solid modeling of the submersible pump diverter was realized by using the method from point to line, line to surface, and then surface to entity.
The use of AutoCAD software can well realize the three-dimensional modeling of the submersible pump diverter, and better ensure that the produced diverter is more in line with the performance of the submersible pump, and has greater effect on improving the product design quality, shortening the development cycle and reducing the production cost. Scientific research and economic significance.
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