Research On Micro-nano Scale Tracer Particle PTV Algorithm And Development Of Software Analysis System

In recent years,with the rapid development of computer,CCD digital camera and image processing technologies,as a new interference-free,transient and full-field velocity measurement method,Particle Tracking Velocimetry can make interference-free measurement of flow field velocity and visualize the results.The PTV technique directly tracks the motion of the tracer particles in the flow field by matching methods to obtain the velocity.Due to its low average effect,accurate and intuitive,it has obvious advantages in measuring two-phase or even multi-phase flow field,providing an effective technical means for researchers to understand the distribution of velocity in flow field,and it has been continuously developed and applied.In this paper,the micro-nano scale tracer particles in gas-solid two-phase flow in fluidized bed are taken as the research object,and combined with relevant theories such as image processing and imaging principles,the design of PTV analysis algorithm for micro-nano scale tracer particles is completed by using C++program language.And through VS2010 software to develop it into a complete set of PTV software analysis system.In this paper,the special features of micro-nano tracer particle imaging are described and analyzed in detail,and the corresponding pre-processing algorithm,post-processing algorithm and particle size analysis algorithm are designed,and the classical matching probability method is improved and applied.The theoretical research content of this paper includes the design of image processing algorithm and the analysis and summary of test results.And the practical content includes the construction of the experimental system,the editing of the theoretical algorithm into the program language,the development of the software analysis system,and the verification of the results by the images collected in the experiment.The results achieved are as follows:(1)According to the detection requirements of flow field movement,the experimental system of gas-solid two-phase flow field is built,and 500nm SiO2 particles are selected as tracer particles.Through a large number of experiments,the inadequacies of the experimental system are gradually found and reasonable analysis and planning are carried out.Through continuous improvement of the system construction method and reasonable adjustment of various experimental parameters,the image acquisition work is finally completed.(2)According to the special features of the micro-nano tracer particle imaging principle,the noise of the image and the gray distribution characteristics of the particle image,combined with the related methods of image processing,the HMGF preprocessing algorithm and ID-PR preprocessing algorithm with strong adaptability and good effect are designed.The verification results show that this method can successfully obtain accurate particle images which are convenient for later particle matching or particle size analysis.(3)The common particle matching methods are compared.Finally,the improved matching probability method is used to complete the particle matching process for two consecutive frames of preprocessed particle images,and the preliminary velocity vector of the flow field is obtained.And the three common flow field post-processing correction algorithms are established.By comparing the characteristics of the results,an improved hybrid post-processing flow field correction algorithm is designed at last.The method overcomes the shortcomings of the common post-processing correction algorithm and achieves satisfactory vector effect.(4)According to the characteristics of PTV particle image,the optical imaging principle of tracer particle and the imaging principle of digital camera,the particle size analysis algorithm of micro-nano scale tracer particle which is dominant in diffraction imaging and the particle size analysis algorithm which is dominant in geometric imaging are established.The aim of particle size analysis is realized.(5)By using Visual Studio 2010 software to complete the preparation of the algorithm and software analysis system development.A set of PTV software analysis system including image analysis,image processing,particle size analysis,flow field vector analysis and vlc file management is formed.It is easy to use and realizes PTV analysis function of flow field.In this paper,the particle images of micro-nano scale tracer particles under PTV experimental conditions are taken as the main research object,and flow field velocity and particle scale are analyzed in combination with relevant image processing methods,which can provide a certain theoretical basis and help for the study of gas-solid two-phase flow field correlation analysis through image processing.