The Research On Image Analysis And Processing For DPIV System In Laser Flow Field

In laser-based flow field measurements, digital particle image velocimetry has already become the most effective method in measuring 2-Dimentional flow field because of its non-intrusive, instant and whole-field characteristics. However, most of the researches on DPIV all over the world hasn't solve out the problems in measuring flow field with high speed and complex structures. Therefore, this paper not only made a comprehensive study in the traditional DPIV system as well as its arithmetic, but also successfully designed and developed its image analysis and processing software. Moreover, this paper provided theoretical basis of how to choose proper tracer particles in experiments.The main work and creative points of this paper are as follows:(1) Based on both Mie light scattering theory and fluid mechanics theory, systematically studied the light scattering characteristics and tracing ability for tracer particles. As for turbulent flows, a method based on the spectral analysis is adopted to solve the BBO equation for liquid flows and gas flows respectively.(2) For the design of DPIV's equipments, originally used three wave-length pulsed laser and three CCD cameras with the purpose of making a breakthrough in the velocity limit achieved by DPIV which is caused by the frame-straddle technique. Furthermore, creatively suggest setting two different time interval (⊿t1 and⊿t1) as the time-sequence control for the three laser pulses.(3) On the development of DPIV's software, made an improvement in the traditional correlation method, such as reducing the area and shortening the searching path. Besides, introduced Gauss curve approach and vector invalidating method to process image data. At the same time, designed a diagram for programming and used computer language VC 6.0 to write the software desktop and its corresponding arithmetic.(4) Make use of the software to process displacement images acquired in the simulated fluid experiments in order to initially prove the practicality of this software.