逆向工程在闭式叶轮反求设计中的应用研究

发布时间：2018-05-15 17:42

本文选题：逆向工程 + 闭式叶轮　；参考：《华北电力大学》2011年硕士论文

【摘要】：20世纪中期,为了消化、吸收国外产品的先进技术,以及复杂曲面零件的检测需要,产生了“实物逆向反求”方法,即逆向工程。这种方法是从已有的实物模型入手,首先对模型进行三维数字化测量,利用测量所得数据,重构实物的CAD模型,再对此模型进行CAE分析、改进、创新,最后制造出新产品。本文针对包含复杂内腔的闭式叶轮,论述了实施逆向工程的具体操作方法。首先介绍了闭式叶轮的正向设计方法,即根据水泵的性能参数(流量、扬程、功率、转速等),计算出叶轮的结构尺寸和叶片的型线坐标值,再依据这些数据绘制叶轮的轴面投影图和叶片的剪裁图。从正向设计方法中分析出,只要知道了叶轮前、后盖板上一系列点的高度H和半径R坐标值,便可以画出叶轮的轴面流道投影图;确定一个高度值H的轴垂面,在此面上分别测量不同角度上的轴面与叶片工作面和非工作面的交点的极坐标值(角度θ和半径R),即可绘制叶片的柱面坐标裁剪图。根据中小型制造企业的实际情况,文章介绍了利用坐标撥床或者坐标铣床以及特制的弹性探针、万能电表等工具进行闭式叶轮的数据采集。这种数据采集方法的原理与三坐标测量机相同,只是配合特制的弹性探针、万能电表等工具,可以进行叶轮流道内部的数据测量。通过分析叶轮的功能和原理,规划了合理的测量区域和测量曲线,即只测叶轮流道内部前、后盖板曲线和叶片工作面和非工作面上的特定曲线。避开了一般逆向测量获得的“点云”数据,也不需要逆向软件对测量的数据进行处理,直接用正向CAD软件进行叶轮模型重构。本文介绍了一种基于Solidworks软件的叶轮模型重构方法,利用Solidworks的多种曲线功能,对生成的初始曲线进行检查、分析和修正;将放样获得的叶片工作面和非工作面延伸至叶轮的前、后盖板,再等距曲面取得叶片与前、后盖板的相交面,实现叶片与前、后盖板的无缝结合,方便后续的质量、体积测量和CAE分析;通过文件读入曲线三维坐标点,可以实现对叶片型线进行参数化驱动的设计方法,方便以后的叶轮改型或创新设计。利用Solidworks Flow Simulation软件,对逆向重建的叶轮进行流体分析。通过对叶轮内部流场进行数值模拟,得到叶轮内部的速度分布图和静压分布图等分析结果。从分布图中可以得出叶轮出口处液体的压力和速度值,根据压力值可以换算出叶轮的扬程,根据速度值可以换算出叶轮的流量,并根据叶轮进出口压力的差值和流量等数据,计算出叶轮的效率。将这些值与原样本叶轮的相应参数相比较,从而验证重建叶轮与原样本叶轮的一致性,判断该逆向工程是否成功。
[Abstract]:In the middle of the 20th century, in order to absorb the advanced technology of foreign products and the inspection needs of complicated curved surface parts, a "reverse engineering" method, namely reverse engineering, was produced. This method starts with the existing physical model, first carries on the three-dimensional digital measurement to the model, uses the measured data, reconstructs the physical CAD model, then carries on the CAE analysis, the improvement, the innovation to this model, finally produces the new product. In this paper, the concrete operation method of reverse engineering is discussed for the closed impeller with complex inner cavity. Firstly, the forward design method of closed impeller is introduced, that is, according to the performance parameters of pump (flow rate, head, power, rotational speed, etc.), the structure dimension of impeller and the coordinate value of blade profile are calculated. Based on these data, the axial projection of the impeller and the cutting diagram of the blade are plotted. From the forward design method, as long as we know the coordinates of height H and radius R of a series of points on the front of the impeller and the back cover plate, we can draw the projection diagram of the axial flow channel of the impeller, and determine the vertical plane of a height value H, On this surface, the polar coordinates (angle 胃 and radius R _ (1) of the intersection point between the axial plane and the blade face and non-working face (angle 胃 and radius R _ (1) at different angles are measured respectively, and the cutting diagram of the cylindrical coordinates of the blade can be drawn. According to the actual situation of the small and medium-sized manufacturing enterprises, this paper introduces the data acquisition of the closed impeller by using coordinate moving machine, coordinate milling machine, special elastic probe, universal meter and other tools. The principle of this data acquisition method is the same as that of the CMM, but it can be used to measure the data inside the impeller runner with the special tools such as elastic probe and universal meter. By analyzing the function and principle of impeller, the reasonable measuring area and measuring curve are planned, that is, only the front and back cover curve of impeller flow passage and the specific curve on blade face and non-working face are measured. It avoids the "point cloud" data obtained by general reverse measurement, and does not need reverse software to process the measured data, and directly uses forward CAD software to reconstruct the impeller model. In this paper, a method of impeller model reconstruction based on Solidworks software is introduced. The generated initial curve is checked, analyzed and corrected by using various curve functions of Solidworks, and the blade face and non-working face obtained by lofting are extended to the front of the impeller. The intersecting surface of the blade and front and back cover is obtained by the back cover plate and isometric curved surface, which realizes the seamless combination of the blade and the front and back cover plate, facilitates the subsequent quality, volume measurement and CAE analysis, and reads the three dimensional coordinate points of the curve through the file, The design method of parametric drive for blade profile can be realized, and it is convenient to modify or innovate the impeller design in the future. Using Solidworks Flow Simulation software, the flow analysis of the reverse reconstructed impeller is carried out. Through the numerical simulation of the flow field inside the impeller, the analysis results of velocity distribution and static pressure distribution inside the impeller are obtained. The pressure and velocity of the liquid at the impeller outlet can be obtained from the distribution map, the head of the impeller can be converted according to the pressure value, the flow rate of the impeller can be converted according to the velocity value, and the data of the difference between the inlet and outlet pressure and the flow rate of the impeller can be obtained. Calculate the efficiency of the impeller. These values are compared with the corresponding parameters of the original sample impeller to verify the consistency between the reconstructed impeller and the original sample impeller and to judge whether the reverse engineering is successful or not.
【学位授予单位】：华北电力大学
【学位级别】：硕士
【学位授予年份】：2011
【分类号】：TH122

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