Research On The Flow Field Measurement Technique By Analyzing The Particle Images

A new untouched measuring technique for two-dimension velocity field developed in recent 20 years, PIV gets the information of velocity field by correlation analysis of the image of flow field, which overcomes the deficiency of touched apparatus measuring in single point.In the dissertation, it is introduced about the development and the main of methods of particle image analysis in the fluvial experimentation of harbor & channel engineering. Based on the technical route combining the theory deduction and fluvial experimentation, which combines the computer technique and the fluvial experimentation, the quick arithmetic and post-treatment of PIV are researched, such as particle image emendation, the identification and modification of error vector and the interposition of flow field.Comparing with real sequence Fourier transform and complex sequence Fourier transform, the Hartley transform for image analysis is the optimal method. The researching arithmetic, ameliorating the diagnose window in correlation analysis, improves the precision of PIV and reduces the time of calculation.The discrete velocities are connected by Delaunay grids to form referring region, and the error vectors in the discrete data can be distinguished, corrected and interposed by continuity principle of flow. Matlab is applied successfully for the post-treatment of flow field.The flow character of discharging sluice in the low weir is researched by PIV, which shows that PIV is feasible to measure the flow phenomenon, either inside or surface of flow.