【作者】 张明亮；

【导师】 陈刚； 许联锋；

【作者基本信息】 西安理工大学 ， 环境工程， 2004， 硕士

【摘要】 随着计算机和图像处理方法的快速发展，粒子图像测速法(Particle Image Velocimetry，简称PIV)也得到了相应的发展。作为一种全流场无接触瞬时测量的工具，PIV测量技术已经广泛地应用于流体及多相流参数的测量，而且具有较高的测量精度。本文简要地回顾了PIV测量技术的一些优点和工程应用，综述了PIV技术发展趋势及意义。 作者在参阅了大量的国内外有关流场试验可视化技术、数字图像处理技术、高速水力学、流体力学等相关文献基础上，设计了一套有关水工模型实验的实验台及相关的水循环系统、光源系统等。水工模型为水利工程中的水垫塘模型，射流入水角有75度和60度两种情况，射流入水流量和塘内水深可使用数显阀位控制器和尾水闸门调节。在此基础上，使用数字图像处理技术中的PIV和PTV(Particle Tracking Velocimetry)算法分别测量了射流入水角75度和60度两种情况水垫塘模型流场的速度场，建立了相应的流场流态图像库、速度场库。同时得到其它的参数如涡量场、等流函数线、紊动能等，这些参数对复杂流动和湍流有重要的研究意义。水射流进入水垫塘可以将气体卷入塘内，形成水垫塘自掺气的水气两相流流场。西安理工大学硕士学位论文使用数字图像处理技术中的PIV和PTV测速技术就射流入水角75度和60度两种情况分别测量了水垫塘模型水气两相流流场的各相速度场，建立了相应的两相流流态图像库。PIV算法通过示踪粒子测量连续相(水流流场)的矢量场，PTV算法对分散相(气相)进行量测，实现了两相的同时测量。在量测之前，先使用相分离技术，实现两相的分离。同时给出了水垫塘内气相(气泡)的特征参数如粒径、浓度分布等。 使用数值软件(CFx)对此水工实验模型的淹没射流流场进行了数值模拟，得到水垫塘内的速度场、等流函数线图，将这些计算结果以可视化结果的形式给出。将数值模拟的结果和数字图像处理的结果相比较分析，发现两种方法之间的速度差别较小，在非边界点处两种方法的速度数据符合相对较好，最小绝对误差为0.OOlm/s，最小相对误差为0.49%。绝对误差较大的是容易引起测量误差的边界点。PIV技术测量的结果可为数值模拟模型的建立打下良好的基础，为数值模拟提供可靠的实验数据。更多还原

【Abstract】 With the speedy development of computer and image processing techniques, PIV (Particle Image Velocimetry) have developed correspondingly. As a tool of whole field, unintrusive and instantaneous measurement, PIV has been used widely in parameter measurement of liquid and multiphase and has good measurement precision. Some project applications and advantages of measurement technique of PIV are reviewed briefly, development tendency of PIV are summarized in this paper.Based on vast literatures related to flow visualization techniques, digital image processing techniques, high speed hydraulics, hydromechanics, author designed a set of test-bed of model, system of water circulation and lamp-house. The model is water cushion pool. There are two cases of 75 and 60 in the experiment. Sphericity electromagnetism valve and trail strobe are separately employed for adjusting entering flux and water deep of pool. PIV and PTV are employed to measure velocity field of model in the two casesof 75 and 60 and flow state image house are set correspondingly. At the same time, contour stream line, vortex, kinetic energy which are computed are important to investigate complex flow and turbulent flow. Air is entrained as water jetting into water cushion pool, the gas-liquid two phase flows field are formed. The every phase velocity field are measured by using PIV and PTV (Particle Tracking Velocimetry) method in the course of jet angle 75and60 in gas-liquid flows of water cushion pool. Image house of two phase flows are set up. PIV measures Vector fields of continuous phase (current field) by measuring tracking particle which traces current field. PTV measures disperse phase (bubble) velocity, this technique realizes simultaneity measurement of two phases. Before measuring velocity, separation technique of two phases was employed to realize the result of separation. At the same time, characteristic parameters such as particle diameter, concentration of bubble are provided in this paper.CFX software is used to simulate flow fields of water cushion pool. Contour stream line, vortex and kinetic energy in water cushion pool are found and offered as visualization form. The results of numerical simulation and PIV are analyzed and compared in this paper. The difference of two methods is relatively small and data of velocity accord preferably, the least absolute error is about 0.001m/s and the least relative error is 0. 49% in no boundary position, absolute error is big in the boundary positions which arouse measurement error. The results of PIV measurement are applied to pave good basement for setting model of numerical simulation and offer reliable data for numerical simulation.更多还原