3D-3C particle image velocity measurement system and method based on integrated imaging technology

Abstract

The invention discloses a 3D-3C particle image velocity measurement system and method based on an integrated imaging technology. The system includes a laser, a laser beam expansion and collimation system, a 3D flow field velocity measurement box, a camera array, a computer, a plane calibration board, and a precision electronic control translation table. The method includes the following steps: putting the plane calibration board in the 3D flow field velocity measurement box to calibrate the camera array; putting a tracer particle in the 3D flow field velocity measurement box, and using the camera array to image the tracer particle at different angles; re-projecting a camera image of the camera array on a known plane in a world coordinate system Z to produce a refocus image; getting a refocus image sequence by changing the Z value at equal intervals, discretizing the refocus image sequence, and saving the gray values to discrete grids; and extracting tracer particle points in different depth regions through a method based on gradient transform of a moving window, determining the positions of the tracer particle points, and reconstructing a tracer particle field. The system and the method have the advantages of high precision and high computation speed, and can be used to highly restore the details of a flow field.

Description

technical field [0001] The invention relates to the technical field of flow field optical test systems, in particular to a 3D-3C particle image velocity measurement system and method based on integrated imaging technology. Background technique [0002] Three-dimensional three-component (3D-3C) particle image velocimetry is an advanced flow field optical testing technology, which calculates the transient three-dimensional Flow field structure and flow trend can be used to measure three-dimensional complex flow fields such as turbulent flow, large-scale, multi-vortex interference, such as the flow field disturbance around the propeller when the helicopter ascends, the air disturbance generated by the bee colony flight, etc. . Currently, there are a variety of 3D-3C flow field measurement methods, such as Tomographic Particle Image Velocimetry, Holographic Particle Image Velocimetry, and Defocusing Particle Image Velocimetry. . The above-mentioned flow field measurement tech...

AI Technical Summary

Problems solved by technology

The above-mentioned flow field measurement techniques have good results in the measurement of small-scale local flow field structures, but their overall visible depth is small. The maximum visible depth in the current technology is about 3 cm, but this is not the case for large-scale flow fields in the depth direction. In the measurement of flow fields such as eddy current and multi-vortex interference, it is far from enough

In addition, when the existing 3D-3C particle image velocimetry system is in a high-concentration tracer particle environment, when the tracer particles are observed from different angles, the particles will be blocked back and forth. Field reconstruction accuracy, and when the concentration of tracer particles is small, the reconstructed particle field is difficult to display the details of the flow field, which means that the corresponding spatial resolution is very limited. In addition, if the camera shooting angle is small , may cause the reconstructed tracer particles to be elongated, which seriously limits the accuracy of 3D particle image velocimetry

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