| With the rapid development of image analysis algorithms and the emergence of laser and CCD,the particle image velocimetry(PIV)has been developed rapidly.PIV technology can realize the measurement of two-dimensional flow field without interference measurement,and the flow field structure can be visually displayed.At present,PIV technology has been successfully applied to the aerodynamic experiment and the hydrodynamic experiment to measurement the two-dimensional flow field,which provides an effective means for the researchers to understand the velocity distribution in the flow field.In this paper,three methods of particle velocity measurement are studied:the particle image velocimetry based on cross correlation algorithm,and the particle tracking velocimetry and hybrid algorithm.The measurement principle,hardware device and algorithm realization of these three techniques are introduced and analyzed one by one.The peak precision and detection window selection in cross-correlation algorithm are analyzed and discussed.In the complex flow field the classical relaxation algorithm is easy to generate the error vector.According to the actual flow field,an improved algorithm is proposed.The improved relaxation algorithm can suppress the error vector well in the complex flow field.The experimental results are obtained by simulation.In order to improve the spatial resolution and precision and save the computational time,the process of the hybrid algorithm is discussed by using the standard particle image and the actual flow field particle image.In this paper,the improved algorithm is used in the hybrid algorithm.The algorithm mentioned in this paper is simulated by MATLAB,and the results are compared and analyzed.The simulation results show that the improved hybrid algorithm has higher matching rate and can save computational time.In addition,the improved hybrid algorithm can reflect the flow field quantitatively and analysis the actual flow,which has high application value. |
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