纹影仪流场密度定量测量技术研究

发布时间：2018-05-24 07:07

本文选题：纹影技术 + 流场　；参考：《西安工业大学》2017年硕士论文

【摘要】：本文首先对传统纹影技术的基本原理和方法进行了阐述,其次介绍了该技术在流体边界层、激波、可燃气体内的对流混合以及风洞和水洞的观测试验等领域的相关应用,并分析了现有不同类型的纹影技术的优缺点。为了解决纹影定量测量方法不完善的问题,提出了一种纹影密度定量计算的新方法,其研究工作的主要内容如下:1.设计了一套纹影密度测量实验装置,该装置主要由透射式纹影光路、刀口控制电路和流场密度定量分析软件共三大部分组成。2.研究了纹影刀口自动寻焦算法、密度定量测量算法以及纹影图像的标定曲线技术。刀口自动寻焦算法以分析寻焦过程中的图像特征为基础,通过图像灰度均匀性比较的方法,将纹影刀口装置的位置自动寻于第二纹影镜焦点位置;密度定量分析算法以纹影仪定量测量原理以基础,通过分析图像灰度大小与未被遮挡的光源像面积的关系,计算得出流场的密度值。3.搭建以矩形电控加热平台上方受热空气为试验对象的实验装置,并且结合所提出的刀口自动寻焦算法、标定曲线技术以及密度定量测量算法三大核心内容,进行了流场密度测量试验,并将测量结果与标准器件测量的密度信息进行比较。实验结果表明:在室温20摄氏度下,寻焦算法的精度在0.3～0.5mm之间,流场密度测量相对误差小于5%。实现了电控加热平台上方受热空气的密度测量,实验结果较为理想,其研究内容为实际应用和流体密度试验的观测提供了一种新思路。
[Abstract]:In this paper, the basic principles and methods of traditional schlieren technique are introduced, and its applications in fluid boundary layer, shock wave, convection mixing in combustible gas, wind tunnel and water tunnel observation are introduced. The advantages and disadvantages of different types of schlieren techniques are also analyzed. In order to solve the problem of imperfection of the quantitative measurement method of schlieren, a new method for quantitative calculation of speckle density is proposed. The main contents of its research work are as follows: 1: 1. A set of experimental device for measuring the density of schlieren is designed. The device is mainly composed of three parts, I. e., transmission schlieren path, knife edge control circuit and quantitative analysis software of flow field density. The automatic focusing algorithm, the density quantitative measurement algorithm and the calibration curve technology of the speckle image are studied. Based on the analysis of image features in the process of focusing, the position of the cutting edge is automatically located in the focus position of the second speculum by comparing the grayscale uniformity of the image. The density quantitative analysis algorithm is based on the principle of quantitative measurement with a grain shaper. By analyzing the relationship between the image gray scale and the image area of the unoccluded light source, the density value of the flow field is calculated. 3. Taking the heated air above the rectangular electric control heating platform as the experimental object, and combining the proposed automatic focusing algorithm of the knife edge, calibration curve technology and density quantitative measurement algorithm three core contents. The flow field density measurement experiment was carried out, and the measured results were compared with the density information measured by standard devices. The experimental results show that the accuracy of the focusing algorithm is between 0.3~0.5mm and the relative error of flow field density measurement is less than 5 at room temperature of 20 degrees Celsius. The density measurement of heated air above the electrically controlled heating platform is realized, and the experimental results are satisfactory. The research content provides a new way for practical application and observation of fluid density test.
【学位授予单位】：西安工业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TH74;TP391.41

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