Design of three-dimensional model of turbocharger

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Three dimensional model design of turbocharger turbine stage based on Reverse Engineering

in the automotive engine industry, turbocharger can improve the exhaust emission pollution of automotive engine. Improving the power and mass ratio of engine, improving the torque characteristics of engine, reducing fuel consumption and engine noise have become the main components of modern automobile and engineering machinery. In the turbocharger. The turbocharger of Vaneless nozzle turbine has been widely used because of its advantages of small efficiency change in a wide speed range, simple structure, easy maintenance and low cost. In the past, the research on compressor is mostly. The research on turbine stage is relatively backward, but this situation is changing. The research on turbine stage is receiving more and more attention in the industry. For the study of turbine stage. At present, CFD technology is widely used for research, which requires that the turbine stage 3D CAD model has enough accuracy. Otherwise, the results and accuracy of CFD simulation will be affected. Then it will affect the design cycle of new products and the perfection of existing products. For manufacturers, they hope to improve the original products in the shortest time to make them more competitive among similar products

reverse engineering is to transform the existing product model or physical model into engineering design model and conceptual model. On this basis, the existing products can be dissected, deepened and recreated. With the development and application of computer technology, especially the theory and technology of computer-aided geometric design, reverse engineering has been continuously developed and has been widely used in product improvement and innovative design, especially for products with complex curved surface shape. It greatly shortens the product development cycle and improves the product accuracy. It is an important means to digest and absorb advanced technology and innovate and develop various new products. It is especially suitable for high-temperature parts, especially in the development of objects with complex shapes or objects composed of free-form surfaces. Reverse engineering is one of the ways to shorten the product development cycle and realize rapid manufacturing

the author uses reverse engineering technology to reconstruct the turbine stage of vehicle turbocharger, so as to obtain a 3D CAD model with sufficient accuracy and pave the way for the accurate calculation of subsequent CFD

1 turbine level thing analysis

a complete reverse engineering process, mainly including three main parts: physical model analysis, data acquisition and processing, and surface reconstruction. Figure 1 shows the physical model of the turbine stage. It can be seen from the figure that the coarse turbine stage consists of turbine and volute. Therefore, in order to complete the three-dimensional CAD model of the turbine stage, the two parts must be reversely operated and finally assembled. See Figure 2 for the specific process

Figure 1 physical model of turbine stage

Figure 2 flow chart of reverse calculation of turbine stage

2 acquisition of point cloud diagram of turbine and volute

use 3dss-mini-ii 3D scanner to scan the turbine and volute respectively. Before scanning, it is necessary to arrange feature points at the feature positions of the solid surface as common reference points, so that during the scanning process, the placement angle of the solid can be changed. It enables the raster to scan all surfaces, and then combines the scanning results of each block through these points. Since the result of scanning is to obtain a large number of "point clouds" on the surface, it is necessary to process the point clouds. Remove the bad points and finally get the outline. For a turbine, its blades are symmetrical. Therefore, only two adjacent blades need to be scanned. The results are shown in Fig. 3, and the point cloud after vortex casing scanning is shown in Fig. 4. The point cloud image results are output in STL file format

Figure 3 point cloud diagram of turbine Figure 4 point cloud diagram of volute

3 curve construction of turbine and volute

after transferring ices files into UG Imageware. Based on points, the system will automatically interpolate a scanning curve, and create a style curve that is easy to modify on this basis. Fig. 5 and Fig. 6 are the official sample curves of the extracted main feature lines respectively. Curve analysis mainly displays its smoothness visually through "curvature comb", and curve modification mainly dynamically modifies the control polygon of the curve through interpolation points to ensure the smoothness of the curve

Figure 5 characteristic curve of blade Figure 6 characteristic curve of volute

4 surface reconstruction of turbine stage

surface reconstruction is quite active in reverse engineering and related fields. Parametric surfaces are widely used in surface fitting because of their good performance in boundary continuity, surface constraints and local control. According to the spatial topology of data points, parametric surface reconstruction can generally be divided into rectangular surface reconstruction and triangular surface reconstruction. Generally, the surface reconstruction in rectangular domain is represented by all wiring using aviation plug-in simple connection NURBS, rational B-spline, Bezier parametric curve and surface, and the data to be processed is required to be a four sided topology. However, the free-form surface reconstruction based on scattered data mostly adopts a triangular topology. For the turbine blade, the feature curve is extracted and reconstructed by NURBS method. The results are shown in Figure 7

the three-dimensional model of the substructure is constructed by using the key characteristic curves of the obtained model. See Figure 8. Combine the blade with the base by Boolean operation and use the circular array method. Make up the number of blades. The turbine CAD model shown in Figure 9 is obtained

for the surface reconstruction of the volute, the same method as the turbine reconstruction is used. However, because the internal flow passage of the volute is a variable cross-section and spiral inlet, the shape is complex and cannot be constructed at one time, so the flow passage is divided into several parts and constructed separately. Finally, the Boolean operation is used to merge the parts, and finally the CAD drawing of the volute shown in Figure 10 is generated

Figure 10 CAD model of volute

5 construction of assembly

in UG. Use the assembly function of its components to assemble the turbine and volute models that have been created according to the assembly clearance measured from the actual model. The final assembly model is shown in Figure 11. In order to facilitate CFD analysis of the actual fluid region of the turbine stage. The backup model is geometrically cleaned to obtain the turbine stage calculation domain in Figure 12

Fig. 11 3D CAD model after assembly Fig. 12 the manufacturing cost of long fiber and thermoplastic polymer compounded into composite materials by pultrusion is basically the same as that of the turbine stage fluid area CAD drawing

6 summary

specifically describes the realization process from entity to 3D CAD model of the turbine stage of automotive turbine booster by using reverse engineering technology, The implementation steps can be summarized as follows:

a. select a 3D scanner with sufficient accuracy to scan the model point cloud

b. extract the key characteristic curves of turbine blade and turbine shell according to the point cloud image

c。 The three-dimensional model of turbine blade and the base model are constructed by using the surface modeling function of the three-dimensional modeling software UG

d. merge the turbine blade with the main body by Boolean operation. The circular array method is used to supplement the number of blades

e. the most important thing is to use the extracted key characteristic lines to generate the three-dimensional model of the vortex shell

f. in UG. Assemble the created turbine and volute models. (end)

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