Visualization of secondary flow behind the square grid models

The secondary flow behind the suqare mech grid submerged in the water channel flow was visualized by the hydrogen bubble method and the dye injection method. The geomotry of gird model used in this experiment is three shape, such as the biplane grid, the intersction grid and the woven screen grid. Each grid model has the open area ratios of β=0.51,0.57 and 0.64,respectively. The flow visualization in the cross section behind the grid model mentioned above clarified the following results : The circulation of flow through any mesh of both the biplane grid and the interesction grid becomes zero, but the secondary flow behind the rod element of grid is in the opposite direction each other. The circulation of flow through any mesh of the woven screen grid has the opposite sign with that of neighboring mesh.