Abstract：Time-resolved particle image velocimetry (TR-PIV) is a widely used non-intrusive flow visualization technique that allows the acquisition of instantaneous flow fields in a planar cross section of a flow. In order to refine the instantaneous spatial structure and study the evolution of a flow, a multispectral-based PIV system is developed to improve the time resolution. With multiple-wavelength monochromatic laser pulses, a planar cross the section of the flow is illuminated, and an image is formed of the tracer particles those are located inside the light sheet. Through a process of image decomposition and interrogation, a velocity vector map is yield. In order to verify the feasibility of the principle, an experimental setup of time-resolved particle image velocimetry is arranged. A light source with three monochromatic spectrums (488，532，632.8 nm) is produced in an accurate time sequence by a laser projector. Particle images at three different instants under the illumination are captured in one snapshot. The time interval between two frames is reduced from 10 ms to 3.4 ms and the time resolution is improved 3 times by means of multispectral-based imaging technique. The experiment result demonstrates that the multispectral-based PIV system is a feasible resolution to obtain instantaneous whole flow field, as well as to improve time resolution.
Key words：Particle image velocimetry; Multispectral; Time resolution
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