Abstract
An experimental investigation of the turbulence structure generated by regular and fractal grids (hereinafter referred to as regular grid turbulence (RGT) and fractal grid turbulence (FGT), respectively) in a water channel is tried by means of stereo particle image velocimetry (stereo PIV). The conventional rectangular array grid and the square-type fractal grid with a fractal iteration of N = 4 [1] are used. The Reynolds number based on the effective mesh size is 2;500 for both cases. Two high-speed video cameras are used to measure threecomponent velocities in a laser sheet. The preliminary results show that the vertical profile of the mean streamwise velocity in FGT is larger in the central area of the water tunnel than in the off-central area, whereas that in RGT is uniform cross-sectionally. The turbulence intensity in FGT is larger than that in RGT.
