Study On Digital Particle Image Velocimetry And Application In Oxidation Ditch Model

Digital Particle Image Velocimetry (DPIV) plays an important role in modern flow research and becomes one of the tendencies in modern fluid velocity survey. With main characteristics of whole field, non-intrusive and dynamic measurement, DPIV has widely used in such varied experiments as aerodynamics, hydrodynamics, combustion and hydromechanism. With the rapid progresses in optics, imaging and computer image processing technologies in a recent decade, conventional two-dimensional DPIV is becoming mature technology. The investigations of Multiphase, micro and three-dimensional DPIV are in great demands because of higher challenges of the new tasks. Foreign researches on DPIV started earlier and their technologies are therefore advanced. However, including almost all of DPIV aspects, domestic researches and their translations to applications lag behind. Hence, the study on DPIV not only has an important science values and a great economic values but also can impel the home applications and industrializations of DPIV.This thesis is mainly concerned with the technology of DPIV and the relative techniques. The researches on the theory and realization methods of DPIV are fully carried out. Especially, emphasis is put on such items as constructing of hardware elements and their influences on measurement result, methods of velocity extraction based on gray image, sub-pixel matching method and the technology of 2D-3cPIV.Though the principle of DPIV is simple, the selection and optimization of system parameters are stricter. Image acquisition is the first step to record the particle images and the main factors to be considered include such parameters as tracer particle diameter, density, shape, scattering performance, seeding uniformity and concentration; exposal time, frame transfer time, resolution, image element scale, spectrum, shutter time, lens distortion, focus length, optical resolution, depth of field of camera; laser pulse interval and power and the generations of light sheet and volumetric light source. The rules of selecting these parameters are a good tracking capability, high quality image and in favor of post-processing algorithm. These factors and their affection on the measurement result are discussed in detail. Furthermore, several formulae are summarized to estimate and set up these parameters.The particle image matching is crucial for determining the two-dimensional velocity field. Therefore this thesis focuses on the matching measures and matching...