Measurements of cylinder’s wake by Tomo-PIV

Tomographic particle image velocimetry (Tomo-PIV)is an advanced optical meas-urement technology,which can acquire three-dimensional three-components (3D3C)flow field structure quantitatively in a complete volume,and can be used as an effective method on turbu-lence,vortex interference and other complex three-dimensional flow field measurement.In order to achieve the measurement application of Tomo-PIV in the FL-5 wind tunnel with 1.5m diame-ter test section of AVIC Aerodynamics Research Institute,the wake of a cylinder with 12mm di-ameter is investigated by means of Tomo-PIV.The flow speed is 15m/s,the measurement vol-ume is illuminated by a 2 ×200 mJ laser,and four 2048 ×2048 pixels CCD cameras with 85mm lens are used to record particles images from different directions.By solving a series of engineer-ing problems,such as diffusion of particles and optical path design,we successfully obtained the Karman rollers flow structure of the cylinder’s wake.Then,we studied the method of the data processing.The measurement volume extends approximately over a region of 95mm×70mm× 8.5mm with the shortest side in the direction of the depth of field,and the particle image spatial resolution is about 20 pixels/mm.There are tens of thousands of vectors recorded at every snap-shot.We can obtain a lot of information about the flow field by Tomo-PIV,much more than that obtained by 2D PIV or stereo-PIV measurement.